alpha-Methyldopa and beta-blockers in hypertension--a comparison of their haemodynamic effects.
1. During acute injection of alpha-methyldopa there is a reduction in the blood pressure within a period of a few hours and a modest reduction in the cardiac output, sometimes due to a modest decrease in heart rate. Frequently the total peripheral resistance is decreased. In contrast, acute injection of beta-blockers induces a marked decrease in heart rate and cardiac output, a compensatory increase in the total peripheral resistance and no decrease in the blood pressure. 2. During long-term use alpha-methyldopa frequently reduces the total peripheral resistance and the reduction in cardiac output is usually modest, at rest as well as during exercise. The beta-blockers reduce the blood pressure, but induce a marked decrease in cardiac output and heart rate. The total peripheral resistance is little affected compared to the pre-treatment level.
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000526:Alprenolol / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008750:Methyldopa / Q000494:pharmacology*; D008790:Metoprolol / Q000494:pharmacology; D005082:Physical Exertion; D011433:Propranolol / Q000494:pharmacology; D013997:Time Factors; D013999:Timolol / Q000494:pharmacology
D000319:Adrenergic beta-Antagonists; D008750:Methyldopa; D013999:Timolol; D000526:Alprenolol; D011433:Propranolol; D008790:Metoprolol