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.

Time course of regression of left ventricular hypertrophy in treated hypertensive patients.

In a prospective study, 32 hypertensive patients with echocardiographic evidence of left ventricular hypertrophy were treated with methyldopa, hydrochlorothiazide, or methyldopa and hydrochlorothiazide combined. Echocardiograms and electrocardiograms were obtained in each of the 32 patients before treatment, at the point of initial blood pressure control, and then one, three, and six months thereafter; in 27 patients these studies were also obtained after 12 and 18 months. Left ventricular end-diastolic posterior wall thickness decreased in seven patients whose blood pressure was controlled with methyldopa alone (p less than 0.01) and in 17 patients whose blood pressure was controlled with methyldopa and hydrochlorothiazide combined (p less than 0.01); in both groups, the reduction in left ventricular posterior wall thickness at end-diastole was apparent one month after blood pressure control was established (p less than 0.05). In contrast, no significant reduction in left ventricular posterior wall thickness at end-diastole was observed in eight patients who had equivalent control of blood pressure with hydrochlorothiazide alone (p = 0.34). During the 18-month follow-up period, ventricular septal thickness at end-diastole decreased in the group treated with methyldopa and hydrochlorothiazide combined (p = 0.03); whereas, ventricular septal thickness at end-diastole appeared to increase in the group treated with hydrochlorothiazide alone (p less than 0.01). These results suggest that evidence of regression of left ventricular hypertrophy may be detected as early as one month after blood pressure is controlled with methyldopa or methyldopa and hydrochlorothiazide combined; whereas, long-term control of hypertension with hydrochlorothiazide alone was not associated with evidence of regression of left ventricular hypertrophy. Although the patient number are small, these data suggest that there are differences in the long-term effects of diuretics and sympatholytic drugs on left ventricular anatomy, which may, in part, relate to divergent effects on the sympathetic nervous system.