Papers by Jeann L Sabino-Carvalho
Function, 2024
Chronic kidney disease (CKD) is characterized by over-activation of the sympathetic nervous syste... more Chronic kidney disease (CKD) is characterized by over-activation of the sympathetic nervous system (SNS) that increases cardiovascular risk. Whether sympathetic baroreflex sensitivity (sBRS) is impaired or intact in CKD remains under-studied and controversial. Furthermore, the downstream effect of SNS activation on blood pressure transduction has not been previously examined in CKD. We tested the hypothesis that sBRS is attenuated, while sympathetic transduction is augmented in CKD. In 18 sedentary patients with CKD stages III-IV (eGFR: 40±14 mL/min) and 13 age-matched controls (eGFR: 95±10 mL/min), beat-to-beat blood pressure (BP; finger photoplethysmography), heart rate (electrocardiography) and muscle sympathetic nerve activity (MSNA; microneurography) were recorded at rest for 10-min. Weighted linear regression analysis between MSNA burst incidence and diastolic BP was used to determine the spontaneous sBRS. Sympathetic-BP transduction was quantified using signal averaging, whereby the BP response to each MSNA burst was tracked over 15 cardiac cycles and averaged to derive the peak change in BP. Compared with controls, CKD patients had an attenuated sBRS [CKD: −1.34 ± 0.59 versus CON: −2.91 ± 1.09 bursts (100 heartbeats)−1 mmHg−1; P = 0.001]. |sBRS| was significantly associated with eGFR (r = 0.69, P < 0.001). CKD patients had attenuated sympathetic-BP transduction compared to controls (0.75 ± 0.7 vs. 1.60 ± 0.8 mmHg; P = 0.010). Resting MSNA was negatively associated with sympathetic transduction (r = −0.57, P = 0.002). CKD patients exhibit impaired sBRS that may contribute to SNS overactivation and cardiovascular risk in this patient population. In addition, CKD patients had an attenuated sympathetic transduction that may counteract the vascular effects of SNS overactivation.
Physiological reports, Apr 1, 2024
The FASEB Journal, Mar 31, 2016
Physiology
Chronic kidney disease (CKD) patients have greater blood pressure reactivity to acute cardiovascu... more Chronic kidney disease (CKD) patients have greater blood pressure reactivity to acute cardiovascular stressors and a higher prevalence of hypertension; however, limited information is available regarding the potential role of impaired baroreflex control in non-dialysis CKD patients. The baroreflex plays a homeostatic role in beat-to-beat blood pressure (BP) regulation and impaired cardiac baroreflex sensitivity (cBRS) has been associated with increased blood pressure reactivity and cardiovascular events. However, previous studies in CKD have shown mixed results or have been confounded with co-morbid conditions such as hypertension. Therefore, the aim of the present study was to test the hypothesis that baroreflex control of heart rate (HR) is attenuated in patients with CKD compared to hypertensive controls. Additionally, we tested whether cardiovascular risk factors such as age, arterial stiffness, and BMI are associated with cBRS in patients with CKD. In 15 stage III-IV CKD patien...
Physiology
Increased blood pressure (BP) variability is a powerful predictor of cardiovascular events and en... more Increased blood pressure (BP) variability is a powerful predictor of cardiovascular events and end-organ damage and is associated with sympathetic overactivity. Given the heightened cardiovascular (CV) risk in patients with chronic kidney disease (CKD), we hypothesized that patients with CKD would exhibit augmented resting beat-to-beat BP variability. Additionally, since aerobic exercise training exerts CV protective effects and has been shown to reduce resting sympathetic activity, we hypothesized that twelve weeks of aerobic exercise training would improve resting beat-to-beat BP variability in patients with CKD. In 25 sedentary patients with CKD stages III-IV [19 male/6 female, age: 62 ± 10 yr, 23 Black/2 White, systolic/diastolic BP: 130 ± 12/73 ± 9 mmHg, BMI: 31 ±7 kg/m2] and 15 controls [11 male/4 female, age: 56 ± 11 yr, 13 Black/2 White, systolic/diastolic BP: 129 ± 12/83 ± 8 mmHg, BMI: 29 ± 3 kg/m2], resting beat-to-beat blood pressure (finger photoplethysmography) was cont...
Physiology
Pre-clinical models suggested that administration of Amiloride at the carotid sinus antagonizes t... more Pre-clinical models suggested that administration of Amiloride at the carotid sinus antagonizes the acid-sensing ion channels (ASICS), an essential component of the mechanoelectrical transducer in the arterial baroreceptors, reducing cardiac baroreflex sensitivity and perturbing the homeostatic beat-to-beat blood pressure (BP) regulation. However, it is still undetermined whether these findings could be translated into humans. Therefore, we determined whether oral administration of Amiloride reduces the spontaneous cardiac baroreflex (cBRS) sensitivity and perturbs BP regulation in humans. Heart rate (HR; electrocardiography) and beat-to-beat BP (finger photoplethysmography) were continuously measured in 5 healthy men (32 ± 6 yrs) during at least 5 min in two different conditions: (1) Control (CTL) and (2) 3 h after of oral administration of Amiloride (AMD – 5 mg + 50 mg of hydrochlorothiazide), a non-selective antagonist of ASICs. Spontaneous cardiac BRS was determined for all sequ...
BMC medical education, Jan 29, 2024
Background Physiology is widely recognized as a difficult course, which can potentially increase ... more Background Physiology is widely recognized as a difficult course, which can potentially increase students' withdrawal and failures rates. Several factors are likely contributing to the difficulties in learning physiology, including inherent features of the discipline as well as aspects related to instructions and/or students' perception. With regards to the later, it is currently unknown how students of exercise physiology think and explain physiology in terms of its cause or consequence (i.e., teleological or mechanistic thinking). Therefore, the aims of the present study were to determine 1) whether undergraduate students' perception of cardiorespiratory physiology during exercise follows a predominant teleological or mechanistic thinking, and 2) whether prior enrollment in physiology courses can influence the predominance of teleological vs. mechanistic thinking. Methods The test instrument was an online questionnaire about exercise physiology consisting of nine incomplete sentences about exercise physiology where students had to choose between a teleological or a mechanistic complement. The questionnaire was administered to undergraduate students in the following areas: 1) Movement Sciences (n = 152), 2) Health-related (n = 81) and, 3) Health-unrelated programs (n = 64). Students in Movement Sciences and Health-related programs were also analyzed separately in the following categories: 1) students who previously undertook physiology courses, and 2) students who did not take physiology courses. Results Overall, all groups presented a percentage of teleological thinking above 58%, which is considerably high. Teleological thinking was significantly higher in health-unrelated programs than health-related and movement sciences programs (76 ± 16% vs. 58 ± 26% vs. 61 ± 25%; P < 0.01). Further, students with prior enrollment in physiology classes presented a significantly lower percentage of teleological thinking than students without physiology classes (59 ± 25% vs. 72 ± 22%, respectively; P < 0.01), but the overall teleological reasoning remained predominant. Conclusions These results confirm the hypothesis that undergraduate students tend to present teleological as opposed to mechanistic thinking in exercise physiology. Furthermore, although undergraduate students with prior enrollment in physiology classes presented significantly lower teleological thinking, it remained highly predominant suggesting that teleological thinking is partially independent of the degree of familiarity with this discipline.
Clinical Autonomic Research
American Journal of Physiology-Heart and Circulatory Physiology
Chronic kidney disease (CKD) is characterized by pronounced exercise intolerance and exaggerated ... more Chronic kidney disease (CKD) is characterized by pronounced exercise intolerance and exaggerated blood pressure reactivity during exercise. Classic mechanisms of exercise intolerance in CKD have been extensively described previously and include uremic myopathy, chronic inflammation, malnutrition, and anemia. We contend that these classic mechanisms only partially explain the exercise intolerance experienced in CKD and that alterations in cardiovascular and autonomic regulation also play a key contributing role. The purpose of this review is to examine the physiological factors that contribute to neurocirculatory dysregulation during exercise and discuss the adaptations that result from regular exercise training in CKD. Key neurocirculatory mechanisms contributing to exercise intolerance in CKD include augmentation of the exercise pressor reflex, aberrations in neurocirculatory control, and increased neurovascular transduction. In addition, we highlight how some contributing factors ...
Universidade Federal de São Paulo (UNIFESP), Aug 30, 2016
Ischemic preconditioning (IPC; brief cycles of ischemia) induces protection against ischemia-repe... more Ischemic preconditioning (IPC; brief cycles of ischemia) induces protection against ischemia-reperfusion injury, which occurs due to the fact that the IPC mediates changes in the metabolism of skeletal muscles and micro and macro vascular functions. Moreover, it has been demonstrated that IPC can improve aerobic and anaerobic performance. However, the mechanisms related to this improvement remain unclear. For example, the IPC effect on maximal oxygen consumption (V? O2max) has been controversial. In part, this controversy can be attributed to lack of strict criteria to assess the V? O2max, as well as methodological flaws, such as lack or poor control of placebo and nocebo effects. Thus, limitations from previous studies were circumvented to test the effect of IPC on aerobic metabolism parameters[running oxygen cost (ROC), lactate threshold (LL) e V? O2max] and endurance performance (Tlim) in well-trained runners. Eighteen high-level athletes were submitted to three interventions in random order [IPC; false ultrasound session (PL), and control (CT)]. The athletes were informed that both IPC and the PL would improve performance compared to CT. The expected improvement of the subjects(vs. CT) was 83 and 89% for the IPC and PL, respectively. After each intervention, gas exchange, blood lactate concentration ([Lac]) and perceived exertion (RPE) were measured during a maximum incremental test. Ten minutes later, a supramaximal constant test was used to verify the V? O2max. ROC (P = 0.85), V? O2max (P = 0.68) RPE (P = 0.58), [Lac] (P = 0.65) and LL (P = 0.74) were similar among IPC, PL and CT. Time to exhaustion at supramaximal load was longer after IPC (166 ± 13 s) and PL (165 ± 13 s) than CT (143 ± 13 s; P <0.05). In summary, these results indicate that the IPC improved aerobic performance in middle and long distance runners, but the improvement was not greater than placebo. Moreover, IPC did not change LL, ROC and V? O2max.O pré-condicionamento isquêmico (PCI; breves ciclos de isquemia) induz proteção contra a lesão provocada por isquemia-reperfusão, o que ocorre devido ao fato do PCI mediar alterações no metabolismo dos músculos esqueléticos e nas funções micro e macro vascular. Além disso, tem sido demonstrado que o PCI pode efetivamente melhorar o desempenho em exercícios aeróbios e anaeróbios. Entretanto, os mecanismos relacionados a esta melhora são desconhecidos. Por exemplo, o efeito do PCI sobre o consumo máximo de oxigênio (V? O2máx) é controverso. Em parte, esta controvérsia pode ser atribuída a falta de critérios rigorosos para avaliar o V? O2máx, bem como a falhas metodológicas, como ausência ou mau controle dos efeitos placebo e nocebo. Assim, as limitações de estudos anteriores foram contornadas para testar o efeito do PCI em parâmetros determinantes do metabolismo aeróbio [custo de oxigênio para correr (COC), limiar de lactato (LL) e V? O2máx] e desempenho de resistência (Tlim) em corredores bem treinados. Para isso, 18 corredores de alto nível foram randomizados em três intervenções, em ordem aleatória [PCI; sessão de ultrassom falsa (PL); e controle(CT)]. Os atletas foram informados que tanto PCI quanto PL melhorariam o desempenho em comparação com CT. A expectativa de melhora dos sujeitos (vs. CT) foi de 83 e 89% para o PCI e PL, respectivamente. Depois de cada intervenção, as trocas gasosas, lactato sanguíneo [Lac] e percepção subjetiva de esforço (PSE) foram avaliadas durante um teste incremental máximo. Dez minutos depois, um teste de carga constante em intensidade supramáxima foi utilizado para verificar o V? O2máx. COC (P = 0,85), V? O2máx (P = 0,68), PSE (P = 0,58), [Lac] (P = 0,65) e LL (P = 0,74) foram semelhantes entre PCI, PL e CT. Tempo de exaustão na carga supramáxima foi semelhante entre PCI (166 ± 13 s) e PL (165 ± 13 s), e ambos PCI e PL apresentaram tempo mais longo que o CT (143 ± 13 s, P < 0,05). Em resumo, estes resultados indicam que o PCI melhorou o desempenho aeróbio em corredores de meio fundo e fundo, mas a melhora não foi superior ao placebo. Além disso, o PCI não provocou efeito sobre o LL, COC e V? O2máx.Dados abertos - Sucupira - Teses e dissertações (2013 a 2016
Journal of Neurophysiology
Attenuated baroreflex gain may contribute to adverse cardiovascular outcomes, including orthostat... more Attenuated baroreflex gain may contribute to adverse cardiovascular outcomes, including orthostatic intolerance symptoms typically observed in patients with Parkinson's disease. We found that the baroreflex gain (assessed by the modified-Oxford technique) is attenuated and accompanied by an increased operating range in patients with Parkinson's disease. These findings highlight that cardiovascular perturbations are required to detect baroreflex impairments and that spontaneous indices do not reveal cardiovagal-baroreflex dysfunction in a middle-aged group of patients with Parkinson's disease.
Clinical Autonomic Research, 2022
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Papers by Jeann L Sabino-Carvalho