[Plasma leucine enkephalin and beta-endorphin levels in patients with essential hypertension and the effects of captopril].

To further study the relationship between endogenous opioid peptides and essential hypertension, we measured the concentrations of plasma leucine-enkephalin (LEK) and beta-endorphin (beta-EP) in 50 patients with essential hypertension by radioimmunoassay and investigated the effects of captopril on them. It was shown that the concentrations of plasma LEK and beta-EP in patients with essential hypertension were lower than those in normotensive subjects. No effects of age and sex were found on the concentrations of plasma LEK and beta-EP, and there was no difference in plasma LEK and beta-EP levels between patients with Stage I essential hypertension and those with Stage II essential hypertension. After a single dose of captopril, blood pressure and plasma angiotensin II decreased, plasma renin activity increased; and plasma LEK and beta-EP levels increased. Plasma LEK and beta-EP levels in patients with essential hypertension increased after one month of captopril treatment. In conclusion, the lower plasma LEK and beta-EP levels in patients with essential hypertension indicate that LEK and beta-EP may play a role in the pathogenesis of essential hypertension, and the depressor effects of captopril may act through LEK and beta-EP, besides blocking formation of angiotension II.