Efeito do treinamento físico no controle barorreflexo da atividade nervosa simpática e freqüência cardíaca em indivíduos hipertensos / The effects of exercise training on baroreflex control of sympathetic nerve activity and heart rate in hypertensive patients

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Previous studies demonstrated that exercise training improves the baroreflex control of heart rate in spontaneously hypertensive rats. However, the effects of exercise training on baroreflex control of sympathetic nerve activity and heart rate in patients with hypertension are unknown. We hypothesized that exercise training would improve baroreflex control of muscle sympathetic nerve activity (MSNA) and heart rate in hypertensive patients and that exercise training would reduce MSNA and blood pressure in these patients. Twenty never-treated hypertensive patients were randomly divided into 2 groups: exercise-trained (n=11, age: 46±2 years) and untrained (n=9, age: 42±2 years) patients. An age-matched normotensive exercise-trained group (n=12, age: 42±2 years) was also studied. Baroreflex control of MSNA (microneurography) and heart rate (ECG) was assessed by stepwise intravenous infusions of phenylephrine and sodium nitroprusside and analyzed by linear regression. Blood pressure was monitored on a beat-to-beat basis. Exercise training consisted of three 60-minute exercise sessions per week for 4 months. Under baseline conditions (before training), blood pressure and MSNA were similar between hypertensive groups but significantly increased when compared with the normotensive group. Baroreflex control of MSNA and heart rate was similar between hypertensive groups but significantly decreased when compared with the normotensive group. In hypertensive patients, exercise training significantly reduced blood pressure (P<0.01) and MSNA (P<0.01) levels and significantly increased baroreflex control of MSNA and heart rate during increases (P<0.01 and P<0.03, respectively) and decreases (P<0.01 and P<0.03, respectively) in blood pressure. The baseline (preintervention) difference in baroreflex sensitivity between hypertensive patients and normotensive individuals was no longer observed after exercise training. No significant changes were found in untrained hypertensive patients. In conclusion, exercise training restores the baroreflex control of MSNA and heart rate in hypertensive patients. In addition, exercise training normalizes MSNA and decreases blood pressure levels in these patients.

ASSUNTO(S)

barorreflexo pressão arterial blood pressure sistema nervoso simpático exercício hipertensão hypertension baroreflex exercise sympathetic nervous system

ACESSO AO ARTIGO

Documentos Relacionados