title: Acute effects of the calcium antagonist, nifedipine, on blood pressure, pulse rate, and the renin-angiotensin-aldosterone system in patients with essential hypertension.
abstract: Ten milligrams nifedipine was administered orally to young and old persons with or without hypertension, and the acute effects of nifedipine on the renin-angiotensin-aldosterone system were studied one half to 3 hours later. Nifedipine reduced blood pressure and increased pulse rate in young and old persons with or without hypertension. Simultaneously, nifedipine produced a significant increase of plasma renin activity in young persons with or without hypertension but failed to do so in old persons with or without hypertension. As a result, angiotensin I and II increased significantly in young persons but not in old persons. Hydralazine elevated aldosterone concentration by stimulating the renin-angiotensin system but nifedipine failed to do so despite its effect on the renin-angiotensin system in young individuals. Since calcium is required to secrete aldosterone, it is suggested that nifedipine blocked aldosterone secretion by the agent's calcium antagonizing action.
mesh_terms: D000328:Adult; D000367:Age Factors; D000450:Aldosterone / Q000097:blood; D000803:Angiotensin I / Q000097:blood; D000804:Angiotensin II / Q000097:blood; D001794:Blood Pressure / Q000187:drug effects*; D002118:Calcium / Q000037:antagonists & inhibitors*; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D006830:Hydralazine / Q000494:pharmacology; D006854:Hydrocortisone / Q000097:blood; D006973:Hypertension / Q000097:blood / Q000188:drug therapy*; D008875:Middle Aged; D009543:Nifedipine / Q000494:pharmacology* / Q000627:therapeutic use; D007703:Peptidyl-Dipeptidase A / Q000097:blood; D011725:Pyridines / Q000494:pharmacology*; D012083:Renin / Q000097:blood; D012084:Renin-Angiotensin System / Q000187:drug effects*
chemical_list: D011725:Pyridines; D000804:Angiotensin II; D006830:Hydralazine; D000450:Aldosterone; D000803:Angiotensin I; D007703:Peptidyl-Dipeptidase A; D012083:Renin; D009543:Nifedipine; D002118:Calcium; D006854:Hydrocortisone