AJP - Endocrinology and Metabolism, Vol 264, Issue 1 E82-E89, Copyright © 1993 by American Physiological Society
Age-related impairment of K(+)- and ACTH-stimulated aldosterone secretion by rat adrenal capsules
K. J. Radke
School of Nursing, University of Rochester, New York 14642.
It has been suggested that the decrease in plasma aldosterone concentration
with advancing age is due to a direct effect of aging on adrenal cortical
function. In this study, aldosterone secretion by adrenal capsules from
male Fischer 344 rats that were 3-5, 11-13, and 19-21 mo of age was
evaluated. Adrenal capsules, comprising the capsule, zona glomerulosa, and
small portions of the zona fasciculata-reticularis, were perifused in
vitro. Basal aldosterone secretion progressively decreased with aging. In
response to concentrations of KCl that ranged from 5.0 to 9.0 mM and to
adrenocorticotropic hormone (ACTH) that ranged from 10(-11) to 10(-8) M,
threshold sensitivity of adrenal capsules to these secretagogues decreased
with aging. Moreover, the magnitude of change in K(+)- and ACTH-stimulated
aldosterone secretion and maximal aldosterone response of the adrenal
capsules to KCl decreased with aging. Thus it is concluded that aging
directly affects basal aldosterone secretion by rat adrenal capsules and
that there is an age-related impairment of threshold sensitivity and
responsiveness of adrenal capsules to the secretagogues, KCl and ACTH.
