Journal of Clinical Endocrinology & Metabolism, Vol 58, 374-377, Copyright © 1984 by Endocrine Society
Partial blockade by naloxone of clonidine-induced increase in plasma growth hormone in hypertensive patients
M Bramnert and B Hokfelt
Studies in animals and man indicate a functional interaction between the
adrenergic and the opiate systems. In the present study the effect of the
opiate receptor blocker naloxone on the increase in plasma GH induced by
clonidine was investigated in eight patients with essential hypertension.
In a randomized order the patients received a bolus dose of naloxone (10
micrograms/kg) or physiological saline followed by a slow infusion of
naloxone (5 micrograms/kg X h) or saline, respectively. Fifteen minutes
after the bolus dose of saline or naloxone, clonidine (3 micrograms/kg) was
infused for 10 min. Clonidine induced a significant increase in plasma GH.
Naloxone pretreatment resulted in a significantly reduced GH increase after
the clonidine infusion. These results indicate that the clonidine-induced
increase in plasma GH in hypertensive man is partly mediated via activation
of opiate receptors which can be blocked by naloxone.
