Responses to exercise in experimental hypertension.

Exaggerated cardiovascular responses to stressful stimuli and behavioural hyperexcitability have been observed in spontaneously hypertensive rats (SHR). The present series of experiments examined blood pressure and heart rate responses of SHR and renal hypertensive rats (RHR) to a combined physical and mental stress in the form of treadmill exercise. SHRs exhibited only slight and selective hyper-responsiveness to exercise in regard to increases in heart rate, whereas, RHRs responded normally. The excessive sensitivity of "older" SHRs is related mainly to slightly lower resting heart rates.