Neuropsychiatric Disease and Treatment, Jul 1, 2021
Objective: To investigate the neuroprotective effect and mechanism of cerebroprotein hydrolysate-... more Objective: To investigate the neuroprotective effect and mechanism of cerebroprotein hydrolysate-I (CH-I) on cerebral ischemia/reperfusion injury in rats. Methods: A total of 100 adult healthy male SD rats were randomly divided into a sham group, model group, CH-I treated group, and cerebrolysin (CBL) positive group, consisting of 20 rats in each group. The middle cerebral artery occlusion/reperfusion (MCAO/R) model of rats was built by inserting a suture into the left external carotid artery (ECA) through the internal carotid artery (ICA). Treatment was performed by intraperitoneal injection of CH-I (20 mg/kg). The neurobehavioral function of rats was evaluated by modified neurological severity scores (mNSS). TTC staining was used to detect the cerebral infarction volume (CIV) of rats. The morphological and structural changes of nerve cells were observed by HE staining and the neuronal apoptosis was counted by TUNEL assay. Immunohistochemical (IHC) analysis was used to detect BDNF and pMEK1/2 expressions. The expressions of BDNF, pMEK1/2, pERK1/2, and pCREB were determined with Western blotting. Results: After treatment with CH-I, the mNSS and CIV of rats were improved (P<0.05). And the CH-I can reduce the degeneration and apoptosis of nerve cells in rats (P<0.01). Western blotting showed that the expressions of pMEK1/2, pERK1/2, and pCREB in rats were increased, while the expression of BDNF was decreased after modeling (P<0.05). After treatment, the expressions of pMEK1/2, pERK1/2, and pCREB in the CH-I group were decreased (P<0.05), while the expression of BDNF was significantly increased (P<0.05) compared with the model group. IHC showed that the expression of BDNF and pMEK1/2 was consistent with Western blotting. Conclusion: It is suggested that the CH-I might play a neuroprotective role by inhibiting the expression of MEK-ERK-CREB and enhancing the expression of BDNF after cerebral ischemia/reperfusion injury, thus improving the neurobehavioral function of MCAO/R rats.
Aim: To analyze the cotransmission characteristics of contractile responses to electric field sti... more Aim: To analyze the cotransmission characteristics of contractile responses to electric field stimulation with submaximal voltage and short train in the rabbit saphenous artery. Methods: Isometric vasoconstriction of the rabbit saphenous arterial rings was recorded, and the sympathetic nerves of the arterial rings were activated with electric field stimulation. Results: Electric stimulation produced contractile responses in a frequency-dependent manner in the rabbit saphenous artery. Selective alpha1-adrenoceptor antagonist, prazosin (1 micromol/L) did not affect the vasoconstriction induced by electric stimulation at 2 Hz significantly, but inhibited 39.9 % - 53.8 % of the vasoconstriction at 8 - 16 Hz. On the other hand, desensitization of the P2X1 receptor with alpha,beta-methylene ATP (3 micromol/L) abolished all the vascular responses induced by stimulation at 2 Hz, and obviously potentiated those induced by stimulation at 16 Hz, but it did not affect the concentration-dependent response curves for exogenous norepinephrine. The vasoconstriction responses induced by electric stimulation were all abolished by the treatment of a combination of prazosin (1 micromol/L) and alpha,beta-methylene ATP (3 micromol/L). Conclusion: The sympathetic and purinergic contractile responses can be induced by 2 Hz stimulation, and ATP is the sole transmitter causing the vasoconstriction in the rabbit saphenous artery. Contractile responses to higher frequencies are related to both norepinephrine and ATP. Desensitization of the P2X1 receptor with alpha,beta-methylene ATP potentiates the vascular responses to electric stimulation via a presynaptic mechanism.
European Journal of Pharmaceutical Sciences, Sep 1, 2015
Doxazosin (DOX), a long-lasting a 1-adrenoceptor antagonist, is used clinically as a racemate tha... more Doxazosin (DOX), a long-lasting a 1-adrenoceptor antagonist, is used clinically as a racemate that consists of two optical isomers. In humans and rats, following oral administration of racemic DOX [(±)-DOX], the plasma concentration of the (À)-isomer is lower than that of the (+)-isomer, but the mechanism for this interaction is not known. In this study, a chiral HPLC with fluorescence detection was used to measure the drug concentrations for analysis of the stereoselective metabolism of DOX in in vivo and in vitro experiments. We found that the plasma levels of the (À)-isomer were significantly lower than those of the (+)-enantiomer following i.v. administration of (±)-DOX to the rats and that the depletion rate constant (k dep) of (À)-DOX (0.0107 ± 0.0007 L/min) was significantly larger than that of (+)-DOX (k dep 0.0088 ± 0.0005 L/min) (p < 0.05) when (±)-DOX was incubated with rat liver microsomes (RLMs). However, (À)-DOX was not depleted faster than (+)-DOX following their separate incubation with RLMs. The metabolism of (À)-or (+)-isomer in RLMs was catalysed by CYP3A because the depletion of the compounds was inhibited by ketoconazole (a potent CYP3A-selective inhibitor) similarly. More importantly, the k dep of (+)-DOX in the 1.0/2.0 and 0.5/2.5 (+)-DOX/(À)-DOX mixtures was significantly lower than that of (À)-DOX in the 1.0/2.0 and 0.5/2.5 (À)-DOX/(+)-DOX mixtures (p < 0.05). In conclusion, although (À)-DOX is not depleted faster than (+)-DOX when only a single isomer of DOX is incubated with rat liver microsomes, it is depleted much faster than (+)-DOX when a mixture of the two isomers was used, suggesting a prominent and stereoselective inhibition of the (À)-isomer over the (+)-isomer at the CYP3A enzyme.
Alzheimer's disease (AD) and type II diabetes mellitus (DM2) are the most common aging-related di... more Alzheimer's disease (AD) and type II diabetes mellitus (DM2) are the most common aging-related diseases, characterized by β-amyloid and amylin accumulation, respectively. Multiple studies have indicated a strong correlation between these two diseases. Amylin oligomerization in the brain appears to be a novel risk factor for developing AD. Although amylin aggregation has been shown to induce cytotoxicity in the neurons via altering Ca 2+ homeostasis, the underlying mechanisms have not been fully explored. Here, we investigated the effects of amylin on the rat hippocampal neurons using calcium imaging and whole-cell patch clamp recordings.. We showed that Ca 2+ response induced by low concentration of hAmylin was abolished by Amylin receptor antagonist AC187. However Ca 2+ response induced by higher concentration of human amylin (hAmylin) was independent with amylin receptor. This effect relied on extracellular Ca 2+. Additionally, blockade of L-type Ca 2+ channels partially reduced hAmylin-induced Ca 2+ response. In whole-cell recordings, hAmylin depolarized membrane potential. Moreover, application of transient receptor potential (TRP) channel antagonist ruthenium red (RR) attenuated hAmylin-induced Ca 2+ increase. Single-cell RT-PCR showed that transient receptor potential vanilloid 4 (TRPV4) mRNA expressed in most of hAmylin-responsive neurons. Meanwhile, selective knockdown TRPV4 channel inhibited hAmylin-evoked Ca 2+ response. These results indicated that different concentration of human amylin (hAmylin) act via different pathways. Amylin receptor mediates the excitatory effects of low concentration of hAmylin. While for the high concentration of hAmylin, hAmylin aggregation precipitated on the neuron membrane activated TRPV4 channels and then triggered membrane voltage-gated calcium channel opening followed by membrane depolarization. Hence, out data suggest that TRPV4 is a key molecular mediator for the cytotoxic effect of hAmylin on hippocampal neurons.
Aim: To study the electrophysiologic effects of uridine triphosphate (UTP) on the guinea pig papi... more Aim: To study the electrophysiologic effects of uridine triphosphate (UTP) on the guinea pig papillary muscles in vitro and purinoceptors related with the action of UTP. Methods: Intracellular microelectrode method was used to record action potentials (AP) in guinea pig papillary muscles. Results: UTP, adenosine triphosphate (ATP), and adenosine diphosphate (ADP) prolonged the action potential duration (APD) concentration dependently in guinea pig papillary muscles. The potency order was UTP=ATP > ADP. There was cross desensitization between the response to ATP and that to UTP, and neither Ado nor alpha, beta-MeATP caused great change in AP of the papillary muscles. The prolongation of APD by UTP was not affected by sustained perfusion with aminophylline. As an osmotic pressure control equivalent to UTP 3 mmol/L, ceftriaxonum 3 mmol/L or NaCl 9 mmol/L induced a marked but slight prolongation of APD. Conclusion: UTP produced APD prolongation through specific and nonspecific actions, and the specific response to UTP was mediated by P2Y2 purinoceptors.
Neuropsychiatric Disease and Treatment, Jul 1, 2021
Introduction: Vascular dementia (VaD), one of the brain injuries, is difficult to be cured, so it... more Introduction: Vascular dementia (VaD), one of the brain injuries, is difficult to be cured, so it is important to take active neuroprotective treatment after its occurrence. Many studies have shown that apoptosis serves an important role in VaD occurrence; therefore, inhibition of apoptosis may contribute to the recovery of neurological function after VaD occurrence. Cerebroprotein hydrolysate-I (CH-I), a neuropeptide preparation which consists of several amino acids and small molecular peptides as the main active constituent, is extracted using a method similar to cerebrolysin (CBL) which has neuroprotective and neurotrophic effects. Methods: In the present study, a VaD model which was constructed using bilateral common carotid artery occlusion (BCCAO) in Kunming mice was applied to examine the neuroprotective effects of CH-I. Results: The results show that CH-I treatment could attenuate the decrease of learning and memory ability, cell apoptosis in the hippocampal CA1 region and inhibit the activation of caspase-3 and caspase-9 in VaD mice. Furthermore, CH-I treatment could also upregulate Bcl-2 protein levels and activate PI3K and Akt. Discussion: We speculate that CH-I may induce a neuroprotective effect activating PI3K/ Akt signaling pathway in VaD mice.
1. A model of aconitine-induced bradycardia and hypotension, which is similar to aconitine poison... more 1. A model of aconitine-induced bradycardia and hypotension, which is similar to aconitine poisoning in humans, was constructed in conscious rats by oral administration. 2. Blood pressure (BP) and heart rate (HR) of Sprague-Dawley rats were measured using a volume pressure recording (VPR) system. The pharmacokinetics of toxic doses of aconitine and its metabolites were analyzed using UPLC-MS/MS. 3. The HR was significantly decreased by 29% at 2 h after oral administration of 200 μg/kg aconitine. When the dose was increased to 400 μg/kg, systolic BP and diastolic BP were significantly decreased by 11% and 12% at 2 h after the administration, except when bradycardia occurred at 2 h and 4 h. The drug concentration-time curve showed a double-peak phenomenon in rats administered a 400 μg/kg dose. The AUC0-12 h value in the 400 μg/kg group significantly increased 0.8-fold compared to the 200 μg/kg group. Moreover, a high plasma concentration of 16-O-demethyaconitine was found in the rats that received two toxic doses. 4. In conclusion, bradycardia and hypotension are induced in conscious rats by a toxic dose of aconitine (400 μg/kg), and there was no significant difference in dose-normalized AUC0-12 h values between oral administrations of 200 μg/kg and that of 400 μg/kg. However, the dose-normalized Cmax and AUC0-12 h values in 200 μg/kg and 400 μg/kg groups were significantly smaller than those in 100 μg/kg group. The metabolites of aconitine, 16-O-demethyaconitine, and benzoylaconitine may also contribute to the hypotensive response.
In this study, the stereoselective pharmacokinetics of doxazosin enantiomers and their pharmacoki... more In this study, the stereoselective pharmacokinetics of doxazosin enantiomers and their pharmacokinetic interaction were studied in rats. Enantiomer concentrations in plasma were measured using chiral high-pressure liquid chromatography (HPLC) with fluorescence detection after oral or intravenous administration of (-)-(R)-doxazosin 3.0 mg/kg, (+)-(S)-doxazosin 3.0 mg/kg, and rac-doxazosin 6.0 mg/kg. AUC values of (+)-(S)-doxazosin were always larger than those of (-)-(R)-doxazosin, regardless of oral or intravenous administration. The maximum plasma concentration (Cmax ) value of (-)-(R)-doxazosin after oral administration was significantly higher when given alone (110.5 ± 46.4 ng/mL) versus in racemate (53.2 ± 19.7 ng/mL), whereas the Cmax value of (+)-(S)-doxazosin did not change significantly. The area under the curve (AUC) and Cmax values for (+)-(S)-doxazosin after intravenous administration were significantly lower, and its Cl value significantly higher, when given alone versus...
Clinical and Experimental Pharmacology and Physiology, Aug 1, 1993
1. The effects of peptide histidine isoleucine (PHI) on pancreatic exocrine secretion were invest... more 1. The effects of peptide histidine isoleucine (PHI) on pancreatic exocrine secretion were investigated in preparations of the isolated and blood-perfused dog pancreas as compared with those of vasoactive intestinal peptide (VIP), secretin and glucagon. 2. Each peptide tested was injected intra-arterially (i.a.) as a single bolus. Graded doses of PHI (3-300 nmol/ kg), VIP (1-100 nmol/ kg) and secretin (0.01-0.3 nmol/ kg) caused dose-dependent increases in the secretion of pancreatic juice and bicarbonate outputs, but had little effect on the protein outputs. Glucagon (0.1-10 pmol/ kg) produced a bell-shaped dose-response curve for the secretory rate, bicarbonate and protein outputs. 3. The secretory activity of 30 nmol/ kg of PHI corresponded roughly to that of 80 pmol/ kg of secretin, 9 nmol/ kg of VIP and 0.6 pmol/ kg of glucagon, respectively. Thus, based on administered dose, PHI was about 375 X less potent than secretin, 3 X less potent than VIP and 20 X more potent than glucagon. 4. The PHI-and VIP-stimulated secretions were inhibited by a VIP antagonist, but not by a glucagon antagonist, SCH23390 (a dopamine D-1 antagonist), L-364718 (a cholecystokinin antagonist) or atropine. 5. Each peptide increased cyclic AMP concentration, but not cyclic GMP concentration, concomitant with the increase in pancreatic secretion. 6. From these results, it is concluded that PHI produces an increase in pancreatic secretion by acting on VIP-preferring receptors on the exocrine pancreatic gland of the dogs. This may be mediated at least in part through the increase of intracellular cyclic AMP concentrations.
Objective To compare the plasma concentrations of S-doxazosin mesylate and S-doxazosin hydrochlor... more Objective To compare the plasma concentrations of S-doxazosin mesylate and S-doxazosin hydrochloride aderministered via digestive system in rats,rabbits and cats,respectively.Methods S-Doxazosin mesylate and S-doxazosin hydrochloride were administered via different way in three different anesthetized animals at different dose,after different time of observing,respectively,blood samples were collected via femoral vein.then the plasma drug concentrations were determined by using a high performance liquid chromatograpy(HPLC) assay.Results The maximum plasma concentration for S-doxazosin mesylate was(51.2±31.0) ng·mL-1,and that for S-doxazosin hydrochloride was(30.6±17.5) ng·mL-1 180 min after p.o.S-doxazosin mesylate and S-doxazosin hydrochloride in rats.The ratio of AUC for S-doxazosin mesylate over hydrochloride within 0～180 min was 1.4:1.The maximum plasma concentration for S-doxazosin mesylate and hydrochloride was(267.1±63.0) and(226.9±123.2)ng·mL-1,respectively,120 min after intr...
Chinese Journal of Pharmacology and Toxicology, 2005
AIM Action of adenosine triphosphate(ATP) on longitudinal muscle strips of the rat distal colon h... more AIM Action of adenosine triphosphate(ATP) on longitudinal muscle strips of the rat distal colon has been reported, however, that of the rat proximal colon remains to be clarified. In this study we investigated the effects of ATP on longitudinal muscle strips isolated from the rat proximal colon and the receptors involved in the effects. METHODS Isometric relaxant and contractile responses to ATP (0.1 μmol·L~ -1-1 mmol·L~ -1) and adenosine (1-100 μmol·L~ -1) in longitudinal muscle strips of the rat proximal colon were observed. RESULTS ATP (0.1 μmol·L~ -1-1 mmol·L~ -1) produced a complicated response including an inhibition of rhythmic contraction and a weakly transient decrease in basic tone (0.05-0.08 g) followed by a concentration-dependent contraction (0.04-0.44 g) in longitudinal muscle strips of the rat proximal colon at resting tension. Tetrodotoxin (0.1 μmol·L~ -1) did not influence the responses to ATP. Adenosine (1-100 μmol·L~ -1) did not produce an obvious contractile response in the preparation at resting tension. Concentration-dependent relaxant responses to ATP (1 μmol·L~ -1-1 mmol·L~ -1) in the preparation precontracted with 5-hydroxytryptamine or with acetylcholine were 23.2%-94.6% or 24.8%-92.4%, however the relaxant responses to adenosine were much weaker than those to ATP. CONCLUSION ATP produces contractile responses mainly via purine and pyrimidine(P)2 receptors and relaxant responses partially via P1 receptors in longitudinal muscle strips of the rat proximal colon.
Aim To study the relationship between chiral structure of doxazosin and alfuzosin and their effec... more Aim To study the relationship between chiral structure of doxazosin and alfuzosin and their effects on heart rate and contractile force of the isolated mouse atrium.Methods Isolated right and left atria of the mouse were prepared,and the effects of doxazosin,alfuzosin and their enantiomers on the heart rate and contractile force were recorded.Results (+) DOX at 30 μmol·L-1 induced cardiac arrest by 31.3% (5 out of 16) in the isolated right atrium,and(-) DOX and (±) DOX at the same concentration induced cardiac arrest by 8.3% (1 out of 12),respectively.No cardiac arrest was induced in other groups.(+) DOX and (+) DOX at used concentrations decreased the heart rate in a concentration-dependent manner(P0.01),and the inhibition on the heart rate (HR) by (+) DOX was stronger than that by (±) DOX in the isolated right atrium(P0.01).(-) DOX at 10 and 30 μmol·L-1 decreased HR(P0.01),but its effect was weaker than (+) DOX.The HR was mildly decreased by(±) ALF and its enantiomers at 10 and 30...
Mitochondria play a critical role in skeletal muscle metabolism and function, notably at the leve... more Mitochondria play a critical role in skeletal muscle metabolism and function, notably at the level of tissue respiration, which conduct muscle strength as well as muscle survival. Pathological conditions induce mitochondria dysfunctions notably characterized by free oxygen radical production disturbing intracellular signaling. In that way, the second messengers, cyclic AMP and cyclic GMP, control intracellular signaling at the physiological and transcription levels by governing phosphorylation cascades. Both nucleotides are specifically and selectively hydrolyzed in their respective 5 0-nucleotide by cyclic nucleotide phosphodiesterases (PDEs), which constitute a multi-genic family differently tissue distributed and subcellularly compartmentalized. These PDEs are presently recognized as therapeutic targets for cardiovascular, pulmonary, and neurologic diseases. However, very few data concerning cyclic nucleotides and PDEs in skeletal muscle, specifically in mitochondria, are reported in the literature. The knowledge of PDE implication in mitochondrial signaling would be helpful for resolving critical mitochondrial dysfunctions in skeletal muscle. Keywords Skeletal muscle Á Mitochondria functions Á Cyclic AMP Á Cyclic GMP Á Cyclic nucleotide phosphodiesterase Abbreviations cAMP Cyclic adenosine 3 0 ,5 0-monophosphate cGMP Cyclic guanosine 3 0 ,5 0-monophosphate
We investigated the effects of V1 IOPC-21268, 1-(1-[4-(3-acetylaminopropoxy)benzoyl]-4-piperidyl)... more We investigated the effects of V1 IOPC-21268, 1-(1-[4-(3-acetylaminopropoxy)benzoyl]-4-piperidyl)-3,4-dihydro-2( 1H)- quinolinone) and V2 (OPC-31260, 5-dimethylamino-1[4-(2-methylbensoylamino)benzoyl]-2,3,4,5-tetrahy dro-1H- benzazepine) vasopressin receptor antagonists on the negative inotropic response to arginine vasopressin (AVP) in the isolated perfused heart preparations of the dog. AVP (7.5-750 pmol) decreased the atrial and ventricular contractile force when the preparation was perfused with constant pressure or constant flow. AVP induced a small increase in sinus rate. Desmopressin, a selective vasopressin V2 agonist, did not change the sinus rate and atrial or ventricular contractile force. OPC-21268 (0.01-3 mumol) and OPC-31260 (0.01-1 mumol) induced a small negative inotropic effect. Both OPC-21268 and OPC-31260 inhibited the negative inotropic response to AVP in a dose-dependent manner. The doses of 50% inhibition (ID50) for OPC-21268 and OPC-31260 on the inotropic effect were 0.30 +/- 0.16 mumol and 0.084 +/- 0.034 mumol, respectively. Neither OPC-21268 nor OPC-31260 affected the acetylcholine-, adenosine- or norepinephrine-induced inotropic and chronotropic effects. It has been reported that the concentration of OPC-21268 that displaced 50% of specific AVP binding is 0.4 microM for V1 receptors and > 100 microM for V2 receptors and the concentration of OPC-31260 is 0.01 microM for V2 receptors and 1 microM for V1 receptors. We, therefore, suggest that AVP directly causes negative inotropic effects mediated at least in part by V1 receptors in the dog heart.
The effects of proteinase inhibitors on the secretion of pancreatic juice were investigated in pr... more The effects of proteinase inhibitors on the secretion of pancreatic juice were investigated in preparations of the isolated and blood-perfused dog pancreas as compared with those of secretin. Each drug tested was administered i.a. Graded doses of gabexate (1-10 mg) elicited dose-dependent biphasic responses for the secretory rates, bicarbonate concentrations and outputs of pancreatic juice, with maximum effects at approximately 5 mg, but had little effect on the protein concentrations. Camostat, at a high dose of 10 mg, caused significant increases in the secretory rate, bicarbonate concentration and output of pancreatic juice over their basal levels, but had little influence on the protein concentration. Secretin (0.03-0.3 U) usually produced similar to gabexate-induced results (1-5 mg). Both bicarbonate and protein concentrations of the juice obtained with gabexate or camostat were almost the same as those obtained with secretin at a similar secretory rate of pancreatic juice, suggesting the secretory action of gabexate or camostat might be similar to that of secretin. In addition, gabexate (3 mg) and camostat (10 mg) elicited more than the respective additive secretory responses in the presence of i.a. infusion of a phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (12 micrograms/min) as well as secretin (0.1 U). These results indicate that gabexate and camostat induce water and bicarbonate secretion by acting directly on ductular cells of the dog pancreas, which might be mediated at least partially through cyclic AMP.
Neuropsychiatric Disease and Treatment, Jul 1, 2021
Objective: To investigate the neuroprotective effect and mechanism of cerebroprotein hydrolysate-... more Objective: To investigate the neuroprotective effect and mechanism of cerebroprotein hydrolysate-I (CH-I) on cerebral ischemia/reperfusion injury in rats. Methods: A total of 100 adult healthy male SD rats were randomly divided into a sham group, model group, CH-I treated group, and cerebrolysin (CBL) positive group, consisting of 20 rats in each group. The middle cerebral artery occlusion/reperfusion (MCAO/R) model of rats was built by inserting a suture into the left external carotid artery (ECA) through the internal carotid artery (ICA). Treatment was performed by intraperitoneal injection of CH-I (20 mg/kg). The neurobehavioral function of rats was evaluated by modified neurological severity scores (mNSS). TTC staining was used to detect the cerebral infarction volume (CIV) of rats. The morphological and structural changes of nerve cells were observed by HE staining and the neuronal apoptosis was counted by TUNEL assay. Immunohistochemical (IHC) analysis was used to detect BDNF and pMEK1/2 expressions. The expressions of BDNF, pMEK1/2, pERK1/2, and pCREB were determined with Western blotting. Results: After treatment with CH-I, the mNSS and CIV of rats were improved (P<0.05). And the CH-I can reduce the degeneration and apoptosis of nerve cells in rats (P<0.01). Western blotting showed that the expressions of pMEK1/2, pERK1/2, and pCREB in rats were increased, while the expression of BDNF was decreased after modeling (P<0.05). After treatment, the expressions of pMEK1/2, pERK1/2, and pCREB in the CH-I group were decreased (P<0.05), while the expression of BDNF was significantly increased (P<0.05) compared with the model group. IHC showed that the expression of BDNF and pMEK1/2 was consistent with Western blotting. Conclusion: It is suggested that the CH-I might play a neuroprotective role by inhibiting the expression of MEK-ERK-CREB and enhancing the expression of BDNF after cerebral ischemia/reperfusion injury, thus improving the neurobehavioral function of MCAO/R rats.
Aim: To analyze the cotransmission characteristics of contractile responses to electric field sti... more Aim: To analyze the cotransmission characteristics of contractile responses to electric field stimulation with submaximal voltage and short train in the rabbit saphenous artery. Methods: Isometric vasoconstriction of the rabbit saphenous arterial rings was recorded, and the sympathetic nerves of the arterial rings were activated with electric field stimulation. Results: Electric stimulation produced contractile responses in a frequency-dependent manner in the rabbit saphenous artery. Selective alpha1-adrenoceptor antagonist, prazosin (1 micromol/L) did not affect the vasoconstriction induced by electric stimulation at 2 Hz significantly, but inhibited 39.9 % - 53.8 % of the vasoconstriction at 8 - 16 Hz. On the other hand, desensitization of the P2X1 receptor with alpha,beta-methylene ATP (3 micromol/L) abolished all the vascular responses induced by stimulation at 2 Hz, and obviously potentiated those induced by stimulation at 16 Hz, but it did not affect the concentration-dependent response curves for exogenous norepinephrine. The vasoconstriction responses induced by electric stimulation were all abolished by the treatment of a combination of prazosin (1 micromol/L) and alpha,beta-methylene ATP (3 micromol/L). Conclusion: The sympathetic and purinergic contractile responses can be induced by 2 Hz stimulation, and ATP is the sole transmitter causing the vasoconstriction in the rabbit saphenous artery. Contractile responses to higher frequencies are related to both norepinephrine and ATP. Desensitization of the P2X1 receptor with alpha,beta-methylene ATP potentiates the vascular responses to electric stimulation via a presynaptic mechanism.
European Journal of Pharmaceutical Sciences, Sep 1, 2015
Doxazosin (DOX), a long-lasting a 1-adrenoceptor antagonist, is used clinically as a racemate tha... more Doxazosin (DOX), a long-lasting a 1-adrenoceptor antagonist, is used clinically as a racemate that consists of two optical isomers. In humans and rats, following oral administration of racemic DOX [(±)-DOX], the plasma concentration of the (À)-isomer is lower than that of the (+)-isomer, but the mechanism for this interaction is not known. In this study, a chiral HPLC with fluorescence detection was used to measure the drug concentrations for analysis of the stereoselective metabolism of DOX in in vivo and in vitro experiments. We found that the plasma levels of the (À)-isomer were significantly lower than those of the (+)-enantiomer following i.v. administration of (±)-DOX to the rats and that the depletion rate constant (k dep) of (À)-DOX (0.0107 ± 0.0007 L/min) was significantly larger than that of (+)-DOX (k dep 0.0088 ± 0.0005 L/min) (p < 0.05) when (±)-DOX was incubated with rat liver microsomes (RLMs). However, (À)-DOX was not depleted faster than (+)-DOX following their separate incubation with RLMs. The metabolism of (À)-or (+)-isomer in RLMs was catalysed by CYP3A because the depletion of the compounds was inhibited by ketoconazole (a potent CYP3A-selective inhibitor) similarly. More importantly, the k dep of (+)-DOX in the 1.0/2.0 and 0.5/2.5 (+)-DOX/(À)-DOX mixtures was significantly lower than that of (À)-DOX in the 1.0/2.0 and 0.5/2.5 (À)-DOX/(+)-DOX mixtures (p < 0.05). In conclusion, although (À)-DOX is not depleted faster than (+)-DOX when only a single isomer of DOX is incubated with rat liver microsomes, it is depleted much faster than (+)-DOX when a mixture of the two isomers was used, suggesting a prominent and stereoselective inhibition of the (À)-isomer over the (+)-isomer at the CYP3A enzyme.
Alzheimer's disease (AD) and type II diabetes mellitus (DM2) are the most common aging-related di... more Alzheimer's disease (AD) and type II diabetes mellitus (DM2) are the most common aging-related diseases, characterized by β-amyloid and amylin accumulation, respectively. Multiple studies have indicated a strong correlation between these two diseases. Amylin oligomerization in the brain appears to be a novel risk factor for developing AD. Although amylin aggregation has been shown to induce cytotoxicity in the neurons via altering Ca 2+ homeostasis, the underlying mechanisms have not been fully explored. Here, we investigated the effects of amylin on the rat hippocampal neurons using calcium imaging and whole-cell patch clamp recordings.. We showed that Ca 2+ response induced by low concentration of hAmylin was abolished by Amylin receptor antagonist AC187. However Ca 2+ response induced by higher concentration of human amylin (hAmylin) was independent with amylin receptor. This effect relied on extracellular Ca 2+. Additionally, blockade of L-type Ca 2+ channels partially reduced hAmylin-induced Ca 2+ response. In whole-cell recordings, hAmylin depolarized membrane potential. Moreover, application of transient receptor potential (TRP) channel antagonist ruthenium red (RR) attenuated hAmylin-induced Ca 2+ increase. Single-cell RT-PCR showed that transient receptor potential vanilloid 4 (TRPV4) mRNA expressed in most of hAmylin-responsive neurons. Meanwhile, selective knockdown TRPV4 channel inhibited hAmylin-evoked Ca 2+ response. These results indicated that different concentration of human amylin (hAmylin) act via different pathways. Amylin receptor mediates the excitatory effects of low concentration of hAmylin. While for the high concentration of hAmylin, hAmylin aggregation precipitated on the neuron membrane activated TRPV4 channels and then triggered membrane voltage-gated calcium channel opening followed by membrane depolarization. Hence, out data suggest that TRPV4 is a key molecular mediator for the cytotoxic effect of hAmylin on hippocampal neurons.
Aim: To study the electrophysiologic effects of uridine triphosphate (UTP) on the guinea pig papi... more Aim: To study the electrophysiologic effects of uridine triphosphate (UTP) on the guinea pig papillary muscles in vitro and purinoceptors related with the action of UTP. Methods: Intracellular microelectrode method was used to record action potentials (AP) in guinea pig papillary muscles. Results: UTP, adenosine triphosphate (ATP), and adenosine diphosphate (ADP) prolonged the action potential duration (APD) concentration dependently in guinea pig papillary muscles. The potency order was UTP=ATP > ADP. There was cross desensitization between the response to ATP and that to UTP, and neither Ado nor alpha, beta-MeATP caused great change in AP of the papillary muscles. The prolongation of APD by UTP was not affected by sustained perfusion with aminophylline. As an osmotic pressure control equivalent to UTP 3 mmol/L, ceftriaxonum 3 mmol/L or NaCl 9 mmol/L induced a marked but slight prolongation of APD. Conclusion: UTP produced APD prolongation through specific and nonspecific actions, and the specific response to UTP was mediated by P2Y2 purinoceptors.
Neuropsychiatric Disease and Treatment, Jul 1, 2021
Introduction: Vascular dementia (VaD), one of the brain injuries, is difficult to be cured, so it... more Introduction: Vascular dementia (VaD), one of the brain injuries, is difficult to be cured, so it is important to take active neuroprotective treatment after its occurrence. Many studies have shown that apoptosis serves an important role in VaD occurrence; therefore, inhibition of apoptosis may contribute to the recovery of neurological function after VaD occurrence. Cerebroprotein hydrolysate-I (CH-I), a neuropeptide preparation which consists of several amino acids and small molecular peptides as the main active constituent, is extracted using a method similar to cerebrolysin (CBL) which has neuroprotective and neurotrophic effects. Methods: In the present study, a VaD model which was constructed using bilateral common carotid artery occlusion (BCCAO) in Kunming mice was applied to examine the neuroprotective effects of CH-I. Results: The results show that CH-I treatment could attenuate the decrease of learning and memory ability, cell apoptosis in the hippocampal CA1 region and inhibit the activation of caspase-3 and caspase-9 in VaD mice. Furthermore, CH-I treatment could also upregulate Bcl-2 protein levels and activate PI3K and Akt. Discussion: We speculate that CH-I may induce a neuroprotective effect activating PI3K/ Akt signaling pathway in VaD mice.
1. A model of aconitine-induced bradycardia and hypotension, which is similar to aconitine poison... more 1. A model of aconitine-induced bradycardia and hypotension, which is similar to aconitine poisoning in humans, was constructed in conscious rats by oral administration. 2. Blood pressure (BP) and heart rate (HR) of Sprague-Dawley rats were measured using a volume pressure recording (VPR) system. The pharmacokinetics of toxic doses of aconitine and its metabolites were analyzed using UPLC-MS/MS. 3. The HR was significantly decreased by 29% at 2 h after oral administration of 200 μg/kg aconitine. When the dose was increased to 400 μg/kg, systolic BP and diastolic BP were significantly decreased by 11% and 12% at 2 h after the administration, except when bradycardia occurred at 2 h and 4 h. The drug concentration-time curve showed a double-peak phenomenon in rats administered a 400 μg/kg dose. The AUC0-12 h value in the 400 μg/kg group significantly increased 0.8-fold compared to the 200 μg/kg group. Moreover, a high plasma concentration of 16-O-demethyaconitine was found in the rats that received two toxic doses. 4. In conclusion, bradycardia and hypotension are induced in conscious rats by a toxic dose of aconitine (400 μg/kg), and there was no significant difference in dose-normalized AUC0-12 h values between oral administrations of 200 μg/kg and that of 400 μg/kg. However, the dose-normalized Cmax and AUC0-12 h values in 200 μg/kg and 400 μg/kg groups were significantly smaller than those in 100 μg/kg group. The metabolites of aconitine, 16-O-demethyaconitine, and benzoylaconitine may also contribute to the hypotensive response.
In this study, the stereoselective pharmacokinetics of doxazosin enantiomers and their pharmacoki... more In this study, the stereoselective pharmacokinetics of doxazosin enantiomers and their pharmacokinetic interaction were studied in rats. Enantiomer concentrations in plasma were measured using chiral high-pressure liquid chromatography (HPLC) with fluorescence detection after oral or intravenous administration of (-)-(R)-doxazosin 3.0 mg/kg, (+)-(S)-doxazosin 3.0 mg/kg, and rac-doxazosin 6.0 mg/kg. AUC values of (+)-(S)-doxazosin were always larger than those of (-)-(R)-doxazosin, regardless of oral or intravenous administration. The maximum plasma concentration (Cmax ) value of (-)-(R)-doxazosin after oral administration was significantly higher when given alone (110.5 ± 46.4 ng/mL) versus in racemate (53.2 ± 19.7 ng/mL), whereas the Cmax value of (+)-(S)-doxazosin did not change significantly. The area under the curve (AUC) and Cmax values for (+)-(S)-doxazosin after intravenous administration were significantly lower, and its Cl value significantly higher, when given alone versus...
Clinical and Experimental Pharmacology and Physiology, Aug 1, 1993
1. The effects of peptide histidine isoleucine (PHI) on pancreatic exocrine secretion were invest... more 1. The effects of peptide histidine isoleucine (PHI) on pancreatic exocrine secretion were investigated in preparations of the isolated and blood-perfused dog pancreas as compared with those of vasoactive intestinal peptide (VIP), secretin and glucagon. 2. Each peptide tested was injected intra-arterially (i.a.) as a single bolus. Graded doses of PHI (3-300 nmol/ kg), VIP (1-100 nmol/ kg) and secretin (0.01-0.3 nmol/ kg) caused dose-dependent increases in the secretion of pancreatic juice and bicarbonate outputs, but had little effect on the protein outputs. Glucagon (0.1-10 pmol/ kg) produced a bell-shaped dose-response curve for the secretory rate, bicarbonate and protein outputs. 3. The secretory activity of 30 nmol/ kg of PHI corresponded roughly to that of 80 pmol/ kg of secretin, 9 nmol/ kg of VIP and 0.6 pmol/ kg of glucagon, respectively. Thus, based on administered dose, PHI was about 375 X less potent than secretin, 3 X less potent than VIP and 20 X more potent than glucagon. 4. The PHI-and VIP-stimulated secretions were inhibited by a VIP antagonist, but not by a glucagon antagonist, SCH23390 (a dopamine D-1 antagonist), L-364718 (a cholecystokinin antagonist) or atropine. 5. Each peptide increased cyclic AMP concentration, but not cyclic GMP concentration, concomitant with the increase in pancreatic secretion. 6. From these results, it is concluded that PHI produces an increase in pancreatic secretion by acting on VIP-preferring receptors on the exocrine pancreatic gland of the dogs. This may be mediated at least in part through the increase of intracellular cyclic AMP concentrations.
Objective To compare the plasma concentrations of S-doxazosin mesylate and S-doxazosin hydrochlor... more Objective To compare the plasma concentrations of S-doxazosin mesylate and S-doxazosin hydrochloride aderministered via digestive system in rats,rabbits and cats,respectively.Methods S-Doxazosin mesylate and S-doxazosin hydrochloride were administered via different way in three different anesthetized animals at different dose,after different time of observing,respectively,blood samples were collected via femoral vein.then the plasma drug concentrations were determined by using a high performance liquid chromatograpy(HPLC) assay.Results The maximum plasma concentration for S-doxazosin mesylate was(51.2±31.0) ng·mL-1,and that for S-doxazosin hydrochloride was(30.6±17.5) ng·mL-1 180 min after p.o.S-doxazosin mesylate and S-doxazosin hydrochloride in rats.The ratio of AUC for S-doxazosin mesylate over hydrochloride within 0～180 min was 1.4:1.The maximum plasma concentration for S-doxazosin mesylate and hydrochloride was(267.1±63.0) and(226.9±123.2)ng·mL-1,respectively,120 min after intr...
Chinese Journal of Pharmacology and Toxicology, 2005
AIM Action of adenosine triphosphate(ATP) on longitudinal muscle strips of the rat distal colon h... more AIM Action of adenosine triphosphate(ATP) on longitudinal muscle strips of the rat distal colon has been reported, however, that of the rat proximal colon remains to be clarified. In this study we investigated the effects of ATP on longitudinal muscle strips isolated from the rat proximal colon and the receptors involved in the effects. METHODS Isometric relaxant and contractile responses to ATP (0.1 μmol·L~ -1-1 mmol·L~ -1) and adenosine (1-100 μmol·L~ -1) in longitudinal muscle strips of the rat proximal colon were observed. RESULTS ATP (0.1 μmol·L~ -1-1 mmol·L~ -1) produced a complicated response including an inhibition of rhythmic contraction and a weakly transient decrease in basic tone (0.05-0.08 g) followed by a concentration-dependent contraction (0.04-0.44 g) in longitudinal muscle strips of the rat proximal colon at resting tension. Tetrodotoxin (0.1 μmol·L~ -1) did not influence the responses to ATP. Adenosine (1-100 μmol·L~ -1) did not produce an obvious contractile response in the preparation at resting tension. Concentration-dependent relaxant responses to ATP (1 μmol·L~ -1-1 mmol·L~ -1) in the preparation precontracted with 5-hydroxytryptamine or with acetylcholine were 23.2%-94.6% or 24.8%-92.4%, however the relaxant responses to adenosine were much weaker than those to ATP. CONCLUSION ATP produces contractile responses mainly via purine and pyrimidine(P)2 receptors and relaxant responses partially via P1 receptors in longitudinal muscle strips of the rat proximal colon.
Aim To study the relationship between chiral structure of doxazosin and alfuzosin and their effec... more Aim To study the relationship between chiral structure of doxazosin and alfuzosin and their effects on heart rate and contractile force of the isolated mouse atrium.Methods Isolated right and left atria of the mouse were prepared,and the effects of doxazosin,alfuzosin and their enantiomers on the heart rate and contractile force were recorded.Results (+) DOX at 30 μmol·L-1 induced cardiac arrest by 31.3% (5 out of 16) in the isolated right atrium,and(-) DOX and (±) DOX at the same concentration induced cardiac arrest by 8.3% (1 out of 12),respectively.No cardiac arrest was induced in other groups.(+) DOX and (+) DOX at used concentrations decreased the heart rate in a concentration-dependent manner(P0.01),and the inhibition on the heart rate (HR) by (+) DOX was stronger than that by (±) DOX in the isolated right atrium(P0.01).(-) DOX at 10 and 30 μmol·L-1 decreased HR(P0.01),but its effect was weaker than (+) DOX.The HR was mildly decreased by(±) ALF and its enantiomers at 10 and 30...
Mitochondria play a critical role in skeletal muscle metabolism and function, notably at the leve... more Mitochondria play a critical role in skeletal muscle metabolism and function, notably at the level of tissue respiration, which conduct muscle strength as well as muscle survival. Pathological conditions induce mitochondria dysfunctions notably characterized by free oxygen radical production disturbing intracellular signaling. In that way, the second messengers, cyclic AMP and cyclic GMP, control intracellular signaling at the physiological and transcription levels by governing phosphorylation cascades. Both nucleotides are specifically and selectively hydrolyzed in their respective 5 0-nucleotide by cyclic nucleotide phosphodiesterases (PDEs), which constitute a multi-genic family differently tissue distributed and subcellularly compartmentalized. These PDEs are presently recognized as therapeutic targets for cardiovascular, pulmonary, and neurologic diseases. However, very few data concerning cyclic nucleotides and PDEs in skeletal muscle, specifically in mitochondria, are reported in the literature. The knowledge of PDE implication in mitochondrial signaling would be helpful for resolving critical mitochondrial dysfunctions in skeletal muscle. Keywords Skeletal muscle Á Mitochondria functions Á Cyclic AMP Á Cyclic GMP Á Cyclic nucleotide phosphodiesterase Abbreviations cAMP Cyclic adenosine 3 0 ,5 0-monophosphate cGMP Cyclic guanosine 3 0 ,5 0-monophosphate
We investigated the effects of V1 IOPC-21268, 1-(1-[4-(3-acetylaminopropoxy)benzoyl]-4-piperidyl)... more We investigated the effects of V1 IOPC-21268, 1-(1-[4-(3-acetylaminopropoxy)benzoyl]-4-piperidyl)-3,4-dihydro-2( 1H)- quinolinone) and V2 (OPC-31260, 5-dimethylamino-1[4-(2-methylbensoylamino)benzoyl]-2,3,4,5-tetrahy dro-1H- benzazepine) vasopressin receptor antagonists on the negative inotropic response to arginine vasopressin (AVP) in the isolated perfused heart preparations of the dog. AVP (7.5-750 pmol) decreased the atrial and ventricular contractile force when the preparation was perfused with constant pressure or constant flow. AVP induced a small increase in sinus rate. Desmopressin, a selective vasopressin V2 agonist, did not change the sinus rate and atrial or ventricular contractile force. OPC-21268 (0.01-3 mumol) and OPC-31260 (0.01-1 mumol) induced a small negative inotropic effect. Both OPC-21268 and OPC-31260 inhibited the negative inotropic response to AVP in a dose-dependent manner. The doses of 50% inhibition (ID50) for OPC-21268 and OPC-31260 on the inotropic effect were 0.30 +/- 0.16 mumol and 0.084 +/- 0.034 mumol, respectively. Neither OPC-21268 nor OPC-31260 affected the acetylcholine-, adenosine- or norepinephrine-induced inotropic and chronotropic effects. It has been reported that the concentration of OPC-21268 that displaced 50% of specific AVP binding is 0.4 microM for V1 receptors and > 100 microM for V2 receptors and the concentration of OPC-31260 is 0.01 microM for V2 receptors and 1 microM for V1 receptors. We, therefore, suggest that AVP directly causes negative inotropic effects mediated at least in part by V1 receptors in the dog heart.
The effects of proteinase inhibitors on the secretion of pancreatic juice were investigated in pr... more The effects of proteinase inhibitors on the secretion of pancreatic juice were investigated in preparations of the isolated and blood-perfused dog pancreas as compared with those of secretin. Each drug tested was administered i.a. Graded doses of gabexate (1-10 mg) elicited dose-dependent biphasic responses for the secretory rates, bicarbonate concentrations and outputs of pancreatic juice, with maximum effects at approximately 5 mg, but had little effect on the protein concentrations. Camostat, at a high dose of 10 mg, caused significant increases in the secretory rate, bicarbonate concentration and output of pancreatic juice over their basal levels, but had little influence on the protein concentration. Secretin (0.03-0.3 U) usually produced similar to gabexate-induced results (1-5 mg). Both bicarbonate and protein concentrations of the juice obtained with gabexate or camostat were almost the same as those obtained with secretin at a similar secretory rate of pancreatic juice, suggesting the secretory action of gabexate or camostat might be similar to that of secretin. In addition, gabexate (3 mg) and camostat (10 mg) elicited more than the respective additive secretory responses in the presence of i.a. infusion of a phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (12 micrograms/min) as well as secretin (0.1 U). These results indicate that gabexate and camostat induce water and bicarbonate secretion by acting directly on ductular cells of the dog pancreas, which might be mediated at least partially through cyclic AMP.
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