Blood pressure, plasma volume, and catecholamine levels during enalapril therapy in blacks with hypertension.
The effect of enalapril, an antihypertensive inhibitor of angiotensin-converting enzyme, on plasma catecholamine levels and plasma volume (PV) has not been well established. In a randomized, double-blind study, 29 subjects (28 blacks and one white) received one of the following dosing regimens: hydrochlorothiazide (HCTZ), 25 mg twice a day (group 1; n = 12); enalapril, 10 mg twice a day (group 2; n = 12); or enalapril, 10 mg twice a day, with HCTZ, 25 mg twice a day (group 3; n = 5). Dosages were doubled after 4 wk if diastolic blood pressure was greater than or equal to 90 mm Hg. After 8 wk of therapy, supine blood pressure decreased by 24.1/16.0 mm Hg (systolic/diastolic) in group 1, by 10.8/4.0 mm Hg in group 2, and by 48.0/27.8 mm Hg in group 3. Mean values of supine plasma levels of norepinephrine, epinephrine, and dopamine did not change with therapy. PV fell 7.9% in group 1, 1.3% in group 2, and 5.0% in group 3. There were no correlations between changes in PV and blood pressure, but a decrease in PV correlated with an increase in plasma norepinephrine levels in the group treated with HCTZ alone (r = -0.65) and in all 29 subjects combined (r = -0.45). Enalapril alone was not very effective in lowering blood pressure in these subjects, but the combination of enalapril with HCTZ was very effective. There was no evidence of a direct effect of enalapril on the sympathetic nervous system or on PV.
D000328:Adult; D044383:Black People; D001794:Blood Pressure / Q000187:drug effects*; D004151:Dipeptides / Q000494:pharmacology / Q000627:therapeutic use*; D004298:Dopamine / Q000097:blood; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D004656:Enalapril; D004837:Epinephrine / Q000097:blood; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006852:Hydrochlorothiazide / Q000494:pharmacology / Q000627:therapeutic use*; D006973:Hypertension / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D010953:Plasma Volume / Q000187:drug effects*; D011897:Random Allocation
D004151:Dipeptides; D006852:Hydrochlorothiazide; D004656:Enalapril; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine