1. Basal levels of pulse rate, blood pressure and rates of sodium and potassium excretion were observed in eight white male patients with mild hypertension and eight age-, sex- and colour-matched controls during an initial rest period of 90 min and then for 5 h after a 1 h period of isometric exercise involving all four limbs in rotation. The studies were repeated on another day with the subjects resting instead of exercising for 1 h.
2. Changes in systolic pressure after exercise were similar in the hypertensive and control groups, whereas the rise in diastolic pressure was higher and the rise in pulse rate lower after exercise in the hypertensive group compared with the control group.
3. The changes in the rate of salt excretion were significantly different in the two groups, the hypertensive group retaining proportionately more sodium and potassium over several hours.