There is evidence that digitalis promote changes in the autonomic and reflex control of the cardi... more There is evidence that digitalis promote changes in the autonomic and reflex control of the cardiovascular system and enhances survival in rats with Heart Failure (HF). The major aim of the present study was to evaluate the effects of digitoxin treatment on basal renal sympathetic nerve activity (rSNA) and on the reflex control of the cardiovascular system by the arterial baroreceptors and cardiopulmonary reflex in HF rats. Male Wistar rats (±200g) were divided into two experimental groups: HF and HF treated with digitoxin in the diet for 60 days (1mg/Kg/day) (HF+DIG). A significant increase in rSNA were found in HF (190 ± 29pps; N= 5) compared to control rats (98 ± 14pps, N=5). Digitoxin treatment leads to a significant decrease and normalizes rSNA in HF+DIG rats (98 ± 14pps, N= 7). The baroreflex sensitivity for the control of rSNA was significantly decreased by treatment (slope: ‐0.69 ± 0.10pps/mmHg, N= 7) when compared to HF group (slope: ‐2.66 ± 0.12pps/mmHg, N= 5). A similar result was found for the cardiopulmonary reflex, digitoxin reduced the fall in heart rate (HF: 180 ± 7bpm, N=8; HF+DIG: ‐126 ± 14bpm, N=9) in response to acute phenylbiguanide administration. Altogether the results demonstrate that the fall in rSNA in response to digitoxin in HF rats is not related to improvement in the reflex control of the cardiovascular system. Central actions of digitoxin may explain the sympathoinhibitory effects of digitalis.Grant Funding Source: CAPES, CNPq and FAPESP (2009/54225‐8)
Autonomic Neuroscience: Basic and Clinical, Sep 1, 2011
daemia, independent of obesity. Thus, in metabolically disparate obese patients diverse mechanism... more daemia, independent of obesity. Thus, in metabolically disparate obese patients diverse mechanisms may underlie the differential effects of depression.
Canadian Journal of Physiology and Pharmacology, 2016
The effects of chronic treatment with digitoxin on arterial baroreceptor sensitivity for heart ra... more The effects of chronic treatment with digitoxin on arterial baroreceptor sensitivity for heart rate (HR) and renal sympathetic nerve activity (rSNA) control, cardiopulmonary reflex, and autonomic HR control in an animal model of heart failure (HF) were evaluated. Wistar rats were treated with digitoxin, which was administered in their daily feed (1 mg/kg per day) for 60 days. The following 3 experimental groups were evaluated: sham, HF, and HF treated with digitoxin (HF + DIG). We observed an increase in rSNA in the HF group (190 ± 29 pps, n = 5) compared with the sham group (98 ± 14 pps, n = 5). Digitoxin treatment prevented an increase in rSNA (98 ± 14 pps, n = 7). Therefore, arterial baroreceptor sensitivity was decreased in the HF group (−1.24 ± 0.07 bpm/mm Hg, n = 8) compared with the sham group (−2.27 ± 0.23 bpm/mm Hg, n = 6). Digitoxin did not alter arterial baroreceptor sensitivity in the HF + DIG group. Finally, the HF group showed an increased low frequency band (LFb: 23 ±...
There is evidence that obesity is associated with increased sympathetic activity and hypertension... more There is evidence that obesity is associated with increased sympathetic activity and hypertension. However, the mechanisms responsible for these changes are not fully understood. Therefore, the aim of the present study was to evaluate the cardiovascular function and the baroreceptor reflex control of renal sympathetic nerve activity (rSNA) in rats exposed to a high-fat diet over different periods (10 and 20 weeks) compared to control rats. Serum leptin levels were assessed for all time points. Male Wistar rats weighing 150-180 g were used. Four groups of rats were studied: control 10 weeks (Ct10), obese 10 weeks (Ob10), control 20 weeks (Ct20), and obese 20 weeks (Ob20). Blood pressure (BP) and rSNA were recorded in urethane-anesthetized rats (1.4 g/kg, intravenous).The sensitivity of rSNA responses to baroreceptor reflex was assessed by changes in BP induced by increasing doses of phenylephrine or sodium nitroprusside. Significant and progressive increases in serum leptin levels were found in the obese rats, but not in the control rats. No changes in basal BP or rSNA were found in the Ob10 and Ob20 groups; however, a significant impairment in the baroreceptor sensitivity was observed in the Ob20 group for phenylephrine (slope Ob20: -0.78 ± 0.12 vs. Ct20: -1.00 ± 0.08 potential per second (pps)/mm Hg, P < 0.05) and sodium nitroprusside (slope Ob20: -0.82 ± 0.09 vs. 1.13 ± 0.13 pps/mm Hg, P < 0.05). The results suggest that the baroreceptor dysfunction that controls the rSNA is an initial change in the obesity induced in high-fat-fed rats, which might be a predictor of sympathoexcitation and hypertension associated to obesity.
There is evidence that digitalis promote changes in the autonomic and reflex control of the cardi... more There is evidence that digitalis promote changes in the autonomic and reflex control of the cardiovascular system and enhances survival in rats with Heart Failure (HF). The major aim of the present study was to evaluate the effects of digitoxin treatment on basal renal sympathetic nerve activity (rSNA) and on the reflex control of the cardiovascular system by the arterial baroreceptors and cardiopulmonary reflex in HF rats. Male Wistar rats (±200g) were divided into two experimental groups: HF and HF treated with digitoxin in the diet for 60 days (1mg/Kg/day) (HF+DIG). A significant increase in rSNA were found in HF (190 ± 29pps; N= 5) compared to control rats (98 ± 14pps, N=5). Digitoxin treatment leads to a significant decrease and normalizes rSNA in HF+DIG rats (98 ± 14pps, N= 7). The baroreflex sensitivity for the control of rSNA was significantly decreased by treatment (slope: ‐0.69 ± 0.10pps/mmHg, N= 7) when compared to HF group (slope: ‐2.66 ± 0.12pps/mmHg, N= 5). A similar result was found for the cardiopulmonary reflex, digitoxin reduced the fall in heart rate (HF: 180 ± 7bpm, N=8; HF+DIG: ‐126 ± 14bpm, N=9) in response to acute phenylbiguanide administration. Altogether the results demonstrate that the fall in rSNA in response to digitoxin in HF rats is not related to improvement in the reflex control of the cardiovascular system. Central actions of digitoxin may explain the sympathoinhibitory effects of digitalis.Grant Funding Source: CAPES, CNPq and FAPESP (2009/54225‐8)
Autonomic Neuroscience: Basic and Clinical, Sep 1, 2011
daemia, independent of obesity. Thus, in metabolically disparate obese patients diverse mechanism... more daemia, independent of obesity. Thus, in metabolically disparate obese patients diverse mechanisms may underlie the differential effects of depression.
Canadian Journal of Physiology and Pharmacology, 2016
The effects of chronic treatment with digitoxin on arterial baroreceptor sensitivity for heart ra... more The effects of chronic treatment with digitoxin on arterial baroreceptor sensitivity for heart rate (HR) and renal sympathetic nerve activity (rSNA) control, cardiopulmonary reflex, and autonomic HR control in an animal model of heart failure (HF) were evaluated. Wistar rats were treated with digitoxin, which was administered in their daily feed (1 mg/kg per day) for 60 days. The following 3 experimental groups were evaluated: sham, HF, and HF treated with digitoxin (HF + DIG). We observed an increase in rSNA in the HF group (190 ± 29 pps, n = 5) compared with the sham group (98 ± 14 pps, n = 5). Digitoxin treatment prevented an increase in rSNA (98 ± 14 pps, n = 7). Therefore, arterial baroreceptor sensitivity was decreased in the HF group (−1.24 ± 0.07 bpm/mm Hg, n = 8) compared with the sham group (−2.27 ± 0.23 bpm/mm Hg, n = 6). Digitoxin did not alter arterial baroreceptor sensitivity in the HF + DIG group. Finally, the HF group showed an increased low frequency band (LFb: 23 ±...
There is evidence that obesity is associated with increased sympathetic activity and hypertension... more There is evidence that obesity is associated with increased sympathetic activity and hypertension. However, the mechanisms responsible for these changes are not fully understood. Therefore, the aim of the present study was to evaluate the cardiovascular function and the baroreceptor reflex control of renal sympathetic nerve activity (rSNA) in rats exposed to a high-fat diet over different periods (10 and 20 weeks) compared to control rats. Serum leptin levels were assessed for all time points. Male Wistar rats weighing 150-180 g were used. Four groups of rats were studied: control 10 weeks (Ct10), obese 10 weeks (Ob10), control 20 weeks (Ct20), and obese 20 weeks (Ob20). Blood pressure (BP) and rSNA were recorded in urethane-anesthetized rats (1.4 g/kg, intravenous).The sensitivity of rSNA responses to baroreceptor reflex was assessed by changes in BP induced by increasing doses of phenylephrine or sodium nitroprusside. Significant and progressive increases in serum leptin levels were found in the obese rats, but not in the control rats. No changes in basal BP or rSNA were found in the Ob10 and Ob20 groups; however, a significant impairment in the baroreceptor sensitivity was observed in the Ob20 group for phenylephrine (slope Ob20: -0.78 ± 0.12 vs. Ct20: -1.00 ± 0.08 potential per second (pps)/mm Hg, P < 0.05) and sodium nitroprusside (slope Ob20: -0.82 ± 0.09 vs. 1.13 ± 0.13 pps/mm Hg, P < 0.05). The results suggest that the baroreceptor dysfunction that controls the rSNA is an initial change in the obesity induced in high-fat-fed rats, which might be a predictor of sympathoexcitation and hypertension associated to obesity.
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