Exercise training attenuates stress-induced hypertension in the rat.

Abstract

The ability of exercise training to block the generation of hypertension produced by chronic stress in the borderline hypertensive rat was tested. Twenty-three male borderline hypertensive rats, F1 offspring of spontaneously hypertensive and Wistar-Kyoto rats, were divided into three groups. Two groups (8 rats per group) were subjected to 2 hours of daily, predictable, uncontrollable tail shock for 12 weeks. One of these groups was also given 2 hours of daily swim stress (exercise trained). A third group served as a maturation control and received neither intervention (n = 7). After 12 weeks of stress, direct recording of blood pressure verified the pattern observed with tail cuff: shock only group, 180/118 +/- 3/3 mm Hg; exercise-trained and shocked group, 166/108 +/- 4/2 mm Hg; and control group, 160/98 +/- 6/4 mm Hg (mean +/- SEM). Systolic and diastolic blood pressures in the shock only group were significantly higher than in both the other groups (p less than 0.05). The control group differed from the exercise-trained and shocked group only in diastolic BP (p less than 0.05). During a short-term stress session plasma norepinephrine levels in the exercise-trained and shocked group were significantly lower than those in the shock only group (555 +/- 56 vs 776 +/- 84 pg/ml; p less than 0.05). These results indicate that an alteration of autonomic function resulted from the exercise training, but its contribution to the resistance of the exercise-trained and shocked rats to stress-induced hypertension is unclear.

Effects of aerobic exercise training on hemodynamic responses during psychosocial stress in normotensive and borderline hypertensive type A men: a preliminary report.

“…The substantial reduction in resting DBP together with an attenuation of DBP reactivity during psychological stress suggests that aerobic exercise training may be of ameliorative benefit to borderline hypertensive patients who might otherwise be at high risk for the development of sustained hypertension. Research supporting this possibility is provided by an animal study that employed a rat model of borderline hypertension and found that daily exercise conveyed some resistance to the development of hypertension associated with exposure to chronic stress (38).…”

The Effects of Exercise Training on Salt-Induced Hypertension in the Borderline Hypertensive Rat

“…Although resting bradycardia is not a direct index of fitness, the Ex-S subjects in the current study had significantly lower resting heart rate compared to the other groups. The demonstration of a significant resting bradycardia in swim-trained BHR has been previously noted (10).…”

“…In one case, the exercise seemed to prevent this disorder from occurring (12) and, in another study, exercise seemed to have am little effect on arterial pressure (13). Second, a previous investigation using the BHR demonstrated that chronic exercise training is capable of protecting this animal from conflict stress-induced hypertension (10). Thus, the examination of exercise training and saltinduced hypertension in the BHR is a logical extension of these studies.…”

“…Specifically, exercise is often cited as one behavior that is capable of exerting a beneficial effect on health (9). Previous laboratory research has suggested that the hypertension produced by exposure to chronic behavioral stress in the BHR can be attenuated by daily episodes of exercise (10). In this report we present data from a study that examined whether exercise is capable of influencing the development of salt-induced hypertension in the BHR.…”

Effects of aerobic exercise training in animal models of hypertension.

“…The increase in plasma concentration of norepinephrine and changes in vascular reactivity induced by environmental stress BHR may contribute to the hemodynamic adaptations observed both in BHR. (45) Cox et al (46) reported that the swimming APT with 12 weeks, attenuated the development of hypertension caused by stress on BHR, having reduced norepinephrine, suggesting an attenuation of the sympathetic nervous system for training. Lutgemeier et al (47) subjected to the BHR animals to swimming APT lasting 22 weeks, 6 times a week, performed twice a day for 1.5 hour.…”