AJP - Regulatory, Integrative and Comparative Physiology, Vol 259, Issue 2 350-R356, Copyright © 1990 by American Physiological Society
Progesterone-cortisol interaction in control of renin activity but not aldosterone
M. Keller-Wood, J. Silbiger and C. E. Wood
Department of Physiology, University of Florida, College of Medicine, Gainesville 32606.
In addition to its effect of inhibiting adrenocorticotropic hormone (ACTH)
secretion, cortisol (hydrocortisone) inhibits the renin-angiotensin system
in both fetal and adult sheep. We have found that progesterone attenuates
the inhibition of ACTH by cortisol. These studies test whether progesterone
interacts with cortisol in control of the renin-angiotensin-aldosterone
system. Conscious adult ewes were infused with vehicle, cortisol (4
micrograms.kg-1.min-1), progesterone (0.5 microgram.kg-1.min-1), or
cortisol with progesterone for 60 min. Beginning 120 min after the start of
the infusion, renin secretion was stimulated by infusing sodium
nitroprusside (10 micrograms.kg-1.min-1 iv). Cortisol infusion decreased
plasma K+ concentration and reduced the plasma renin activity (PRA) and
aldosterone responses to nitroprusside. Progesterone alone had no effect on
PRA, aldosterone, or K+. Progesterone reduced the inhibition of PRA, but
not aldosterone or K+, by cortisol. The data also indicate that the
suppression of renin, as well as the suppression of ACTH, involves
receptors or intracellular mechanisms with which progesterone interacts,
whereas the inhibition of aldosterone involves a mechanism that
progesterone does not affect.
