AJP - Endocrinology and Metabolism, Vol 252, Issue 1 E118-E123, Copyright © 1987 by American Physiological Society
Specificity of effect of osmolality on aldosterone secretion
R. E. Taylor Jr, J. T. Glass, K. J. Radke and E. G. Schneider
Small (3-7 mM) changes in [NaCl] have a marked inverse effect on
angiotensin II- or K-stimulated aldosterone secretion by the isolated,
perfused canine adrenal gland. The effect is due to the accompanying
changes in osmolality rather than to the changes in [Na] or [Cl]. The
present study was undertaken to determine whether osmolality is a specific
and discrete signal that modulates the secretion of aldosterone only or is
simply a nonspecific physical factor that alters the secretion of other
adrenocortical hormones as well. The study also determined whether small
changes in osmolality affect the conversion of corticosterone to
aldosterone. The secretion of both cortisol and aldosterone by isolated
canine adrenal glands responded in a dose-dependent fashion to
adrenocorticotropin (ACTH), but in contrast to the rapid and potent
modulating action of osmolality reported previously for angiotensin II- or
K-stimulated aldosterone secretion, changes in osmolality at the midpoint
of ACTH infusion had no detectable effect on either cortisol secretion or,
unexpectedly, aldosterone secretion. This indicates that osmolality is a
highly specific signal that modulates responsiveness of the zona
glomerulosa to the factors, angiotensin II and K, which are considered to
be most important in the acute regulation of aldosterone secretion, but
does not influence secretion of cortisol by inner zones of the adrenal
cortex. In glands treated with agents that block aldosterone production
from endogenous precursors, small changes in osmolality had no detectable
effect on the conversion of exogenous corticosterone to
aldosterone.(ABSTRACT TRUNCATED AT 250 WORDS)
