Exercise Training Restores Baroreflex Sensitivity in Never-Treated Hypertensive Patients

Abstract

Abstract-The effects of exercise training on baroreflex control of sympathetic nerve activity in human hypertension are unknown. We hypothesized that exercise training would improve baroreflex control of muscle sympathetic nerve activity (MSNA) and heart rate (HR) in patients with hypertension and that exercise training would reduce MSNA and blood pressure (BP) in hypertensive patients. Twenty never-treated hypertensive patients were randomly divided into 2 groups: exercise-trained (nϭ11; age: 46Ϯ2 years) and untrained (nϭ9; age: 42Ϯ2 years) patients. An age-matched normotensive exercise-trained group (nϭ12; age: 42Ϯ2 years) was also studied. Key Words: hypertension Ⅲ baroreflex sensitivity Ⅲ sympathetic nerve activity Ⅲ exercise Ⅲ blood pressure T here is accumulated evidence that arterial baroreflex plays an important role in the regulation of the cardiovascular system. During spontaneous variation of blood pressure (BP), stimulation or deactivation of the arterial baroreceptors located in the carotid sinus and aortic arch causes reflex bradycardia and tachycardia, respectively. At the vascular level, stimulation of the arterial baroreceptors results in sympathetic inhibition and, in consequence, reflex vasodilation. In contrast, the deactivation of the arterial baroreceptors elicits sympathetic-mediated vasoconstriction. 1 All of these responses work in concert to maintain the BP levels in the reference range. 1It has been described that arterial baroreflex sensitivity can be profoundly altered in some cardiovascular diseases. 2,3 In hypertension, some investigators, 4 -6 but not all, 7-9 observed that baroreflex control of heart rate (HR) and sympathetic nerve activity is significantly reduced. This autonomic dysfunction seems to correlate with an increase in sympathetic outflow and in BP levels. 10 On the other hand, previous studies have demonstrated that regular exercise causes significant changes in baroreflex control of HR in experimental hypertension. Exercise training improves baroreflex control of HR during the increase and decrease of BP in spontaneously hypertensive rats. 11,12 Furthermore, these studies indicate that the improvement in baroreflex sensitivity is, in part, mediated by the enhancement of the aortic depressor nerve sensitivity. In humans with hypertension, little information exists regarding the effects of exercise training on the baroreflex sensitivity. One of the few studies showed that exercise training caused a modest improvement in baroreflex bradycardia. 13 Thus, the effects of regular exercise on the baroreflex control of sympathetic nerve activity in humans with hypertension are unknown.It has been consistently shown that exercise training is a powerful nonpharmacological strategy to reduce BP levels in humans with hypertension. 14 -16 However, the mechanisms involved in the BP reduction after exercise training are still a matter of discussion. In the present study, we investigated the

Physical exercise improves cardiac autonomic modulation in hypertensive patients independently of angiotensin-converting enzyme inhibitor treatment

“…18,19 Physical exercise may promote adjustments in cardiovascular control sites, such as the hypothalamus, solitary tract nucleus and the rostral ventrolateral medulla. These adaptations may occur via neural remodeling or endogenous factors, such as nitric oxide.…”

“…13 Regular physical exercise reduces AP, 14,15 adjusts body composition, 16,17 increases aerobic capacity, 15,16 controls serum fat levels 16 and improves cardiac autonomic control. 18 The benefits of aerobic physical training on cardiac autonomic control have been well documented in experimental and clinical studies. [19][20][21] Regular physical exercise promotes a tonic decrease in sympathetic autonomic control and an increase in vagal control.…”

Preventive role of exercise training in autonomic, hemodynamic, and metabolic parameters in rats under high risk of metabolic syndrome development

“…This result was accompanied by hypertension during the night (phase in which animals are most active) and increased sympathetic modulation (10). These studies suggest that the autonomic nervous system is a critical target during chronic excessive fructose consumption.As a non-pharmacological treatment, aerobic exercise training of moderate intensity has been proven effective to mitigate fructose-induced hypertension in rats (28), and in humans it has been considered an important component in the treatment and prevention of cardiovascular disease (7).Although aerobic exercise is an important non-pharmacological tool in the treatment of cardiovascular diseases (13,16,17,19), little is known about the mechanisms by which exercise acts on the model of a high-fructose diet. Moreover, it is not known whether aerobic exercise of moderate intensity, performed concomitantly with a high-fructose diet, can minimize the cardiovascular, autonomic, and metabolic derangements promoted by a high-fructose diet in rats.…”

Cardiac and peripheral autonomic control in restrictive cardiomyopathy

“…Therefore, it is evident that baroreceptors play a very important role in the normal regulation of the circulatory system and exert a major inhibitory influence on sympathetic outflow 42, 43. Decreased BRS, even in the presence of beta blockade,44 has been directly associated with worsening outcomes in patients with cardiovascular disease 45.…”