[Changes in plasma neuropeptides before and after clonidine in patients with essential hypertension].

Plasma concentrations of beta-endorphin (beta-EP), leucine enkephalin (LEK), arginine vasopressin (AVP), neurotensin (NT), renin activity (PRA) and angiotensin II (AT-II) were determined before and after the treatment with clonidine in 117 patients with essential hypertension. Before the treatment, the patient group had lower levels of beta-EP and LEK (P < 0.001), higher levels of AVP, PRA and AT-II (P < 0.05-0.01), as compared with those in control group. After 14 days of the treatment, plasma levels of beta-EP, LEK increased significantly (P < 0.001), and correlated negatively with the decrease of the mean artery pressure (r = -0.369 and r = -0.441, respectively, P < 0.01). PRA and AT-II decreased significantly (P < 0.05, P < 0.01). Decrease of AVP level was also observed, but did not reach the statistical significance. NT did not change both before and after the treatment. These data suggest that beta-EP and LEK may be involved in pathogenesis of hypertension and in hypotensive action of clonidine.