Influence of exercise training on reactivity and contractility of arterial strips from hypertensive rats.

To determine whether the lowered resting blood pressure values in hypertensive rats were associated with changes in vascular reactivity and/or contractility, helical strips were obtained from different arteries from exercise-trained (running and swimming) hypertensive rats and from running normotensive rats. Each subgroup contained nontrained controls for comparison. Changes in muscle aerobic enzymes, maximum O2 consumption, and body weight indicated that a training effect had occurred. When norepinephrine was added in a dose-response manner to the testing chamber containing helical strips from either the descending aorta, femoral artery, or renal artery, there were no significant differences in reactivity (the negative log dose-response curve) attributable to the training of hypertensive or normotensive groups. However, the trained hypertensive rats exhibited a trend for lower contractility values (dyn/mm2) in some but not all of the strips tested. From these results, we concluded that the lowered resting blood pressures associated with exercise training of hypertensive rats could not be explained by changes in vascular reactivity of their arterial strips.