Response of the systemic pulmonary circulation to labetalol at rest and during exercise.
1 Labetalol was administered to 18 hypertensive patients for an average duration of 2.44 weeks, with an average final daily dose of 1.65 g (principally to study its short-term haemodynamic effects). 2 Labetalol decreased resting heart rate by 16% and maximal exercise heart rate by 21%; the phenylephrine-induced increase in systolic brachial arterial pressure was reduced by 36%. 3 During labetalol treatment brachial arterial pressure was decreased by 29/15 mmHg in the recumbent position, by 41/23 mmHg at rest sitting and by 53/23 mmHg at maximal exercise; total peripheral resistance was not significantly affected at rest recumbent but was reduced at sitting and at exercise; cardiac output was decreased in all conditions. 4 Labetalol reduced mean pulmonary arterial and capillary wedge pressures only in the sitting position. Pulmonary vascular resistance remained unchanged. 5 The drug produced significant decreases in plasma renin activity and in plasma aldosterone concentration.
D000328:Adult; D000450:Aldosterone / Q000097:blood; D004983:Ethanolamines / Q000494:pharmacology*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D007741:Labetalol / Q000494:pharmacology*; D008297:Male; D010656:Phenylephrine / Q000494:pharmacology; D005082:Physical Exertion; D011652:Pulmonary Circulation / Q000187:drug effects*; D012083:Renin / Q000097:blood; D012146:Rest
D004983:Ethanolamines; D010656:Phenylephrine; D000450:Aldosterone; D012083:Renin; D007741:Labetalol