The effect of captopril and propranolol on the responses to posture and isometric exercise in patients with essential hypertension.

The effects of captopril and propranolol on blood pressure, heart rate and plasma noradrenaline, renin and aldosterone, and on the responses to changes in posture and to isometric exercise were measured in patients with essential hypertension. During placebo administration blood pressure, heart rate and plasma noradrenaline rose on standing and during isometric exercise. The rise in diastolic blood pressure during isometric exercise correlated significantly with the rise in plasma noradrenaline. During captopril treatment blood pressure was significantly lower than during placebo administration when the patients were lying, standing or sitting, but the reduction during isometric exercise was not significant. Plasma renin increased, but heart rate, plasma noradrenaline and plasma aldosterone remained unchanged. The acute changes in blood pressure, heart rate and plasma noradrenaline produced by standing and isometric exercise during captopril treatment were similar to those during placebo administration. During propranolol treatment diastolic blood pressure was significantly lower than during placebo administration when the patients were lying, standing or sitting and during isometric exercise. Heart rate also fell. Plasma noradrenaline during standing, sitting and isometric exercise was significantly greater than during placebo administration. The changes in plasma noradrenaline measured during propranolol treatment with the patients supine were negatively correlated with noradrenaline values obtained during placebo administration: plasma noradrenaline fell in patients with higher, and increased in those with lower, initial concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)