Family history of hypertension, exercise training, and reactivity to stress in rats.

In this study we sought to assess the role of exercise training on blood pressure (BP) reactivity to tailshock stress in rats with varying family histories of hypertension. Exercise training consisted of swimming 90 min per day in isothermic water for either 2, 6, or 10 months, beginning at 2 months of age. Control subjects were age-matched and did not exercise daily. Rats with either zero (Wistar-Kyoto), 1 (borderline hypertensive), or 2 (spontaneously hypertensive) hypertensive parents were studied. At the appropriate age, femoral artery catheters were implanted and rats were studied at rest and in response to a 20-min stress session. Exercise training reduced basal BP, especially in rats with a positive family history that were exercised for the longest duration. Reactivity to stress was actually significantly enhanced in trained rats. Thus, these data do not support the reactivity hypothesis, but suggest several reasons why the literature has been so inconsistent. The discussion emphasizes the importance of basal, rather than phasic, BP responses resulting from exercise training.