title: Physiologic mechanisms of bupicomide- and hydralazine-induced increase in plasma renin activity in hypertensive patients.
abstract: A study was made of the possible mechanisms underlying bupicomide- and hydralazine-induced increase of plasma renin activity. Six patients with mild to moderate hypertension were treated with both bupicomide and hydralazine on separate occasions in random order. Bupicomide lowered mean arterial pressure from 124.2 +/- 3.7 mm Hg (mean +/- SE) to 107.2 +/- 3.9 mm Hg (P less than 0.001). The associated increase in plasma renin activity was 1.27 ng/ml per hour and the increase in heart rate was 16.5 beats/min. Hydralazine reduced mean arterial pressure from 124.2 +/- 3.7 mm Hg to 107.0 +/- 2.0 mm Hg (P less than 0.01). The associated increase in plasma renin activity was 2.20 ng/ml per hour and the increase in heart rate was 22.4 beats/min. Plasma renin activity during bupicomide and hydralazine administration correlated positively with control plasma renin activity (r = 0.98, P less than 0.001). The log of plasma renin activity correlated positively with heart rate (r = 0.51, P less than 0.02) and negatively with mean arterial pressure (r = -0.62, P less than 0.005). We conclude that control plasma renin activity is a major determinant of change in plasma renin activity during administration of bupicomide or hydralazine. Both an increase in sympathetic activity and a decrease in perfusion pressure may contribute to the bupicomide- and hydralazine-induced increase in plasma renin activity, possibly by a baroreceptor-mediated increase in adrenergic tone.
mesh_terms: D000328:Adult; D000959:Antihypertensive Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001794:Blood Pressure / Q000187:drug effects; D005260:Female; D005669:Fusaric Acid / Q000031:analogs & derivatives / Q000627:therapeutic use*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006830:Hydralazine / Q000494:pharmacology* / Q000627:therapeutic use; D006973:Hypertension / Q000097:blood* / Q000188:drug therapy / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010848:Picolinic Acids / Q000627:therapeutic use*; D010919:Placebos; D012083:Renin / Q000097:blood*
chemical_list: D000959:Antihypertensive Agents; D010848:Picolinic Acids; D010919:Placebos; D006830:Hydralazine; D012083:Renin; D005669:Fusaric Acid