AJP - Endocrinology and Metabolism, Vol 247, Issue 5 604-E608, Copyright © 1984 by American Physiological Society
Effects of alpha-agonist on renin and prostaglandin E2 release in anesthetized dogs
K. Takahashi, H. Hisa and S. Satoh
The relationship between renin release and renal prostaglandin (PG)
production induced by the alpha-agonists methoxamine and
alpha-methylnorepinephrine was examined in anesthetized dogs. Both
intrarenal infusions of methoxamine (1, 3, and 5 micrograms/min) and
alpha-methylnorepinephrine (0.37, 1, and 2 micrograms/min) resulted in a
dose-dependent decrease in renal blood flow to a slight degree. Methoxamine
dose-dependently increased the renin secretion rate but failed to increase
the PGE2 secretion rate. In contrast, alpha-methylnorepinephrine failed to
affect the renin secretion rate but dose-dependently increased the PGE2
secretion rate. The effect of methoxamine (5 micrograms/min) on renin
release was abolished by the intrarenal alpha 1-adrenoceptor blockade with
prazosin (3 micrograms/min) but was not affected by the intrarenal alpha
2-adrenoceptor blockade with yohimbine (30 micrograms/min). The effect of
alpha-methylnorepinephrine (2 micrograms/min) on PGE2 release was abolished
by yohimbine but not by prazosin. These results suggest that there is a
dissociation between renin release and renal PG production induced by
alpha-agonists and that renal alpha 1- and alpha 2-adrenoceptors may
participate in renin and PGE2 release, respectively.
