Enhanced response of plasma prolactin to metoclopramide during chronic converting enzyme inhibition

The effect of chronic converting enzyme inhibition with enalapril on the PRA, PRL and plasma aldosterone responses to metoclopramide was studied in 10 patients with mild to moderate essential hypertension. Enalapril reduced supine blood pressure and increased heart rate significantly. PRA and urinary sodium excretion rose significantly. PRA levels did not change after metoclopramide neither during placebo nor during enalapril. The aldosterone response to metoclopramide was not altered by enalapril, indicating that this response is independent of the renin-angiotensin system. The PRL response to metoclopramide was considerably enhanced after 4 weeks of treatment with enalapril. It is proposed that enalapril, by decreasing the formation of angiotensin II, increases the prolactin reserve.