Potassium-induced aldosterone secretion involves a cl- -dependent
mechanism.
Wang, Wei, and Edward G. Schneider.
Department of Physiology and Biophysics, University of Tennessee,
Memphis, 894 Union Avenue, Memphis, Tennessee 38163
APStracts 3:0271R, 1996.
Stimulation of aldosterone secretion by increases in extracellular
potassium concentration is associated with increases in the volume of
the adrenal glomerulosa cell. Because increases in cell volume have
been associated with increases in aldosterone secretion, the effect
of preventing the potassium-induced increase in cell volume by
removal of chloride from the medium on the response of dispersed
bovine glomerulosa cells grown in primary culture was determined.
Totally replacing the chloride ion with the methylsulfate ion
prevented the increase in cell volume and significantly suppressed
the increase in aldosterone secretion normally associated with
increasing [K] to 10 mM. In the absence of Cl-, the increase in
cytosolic calcium concentration ([Ca2+]c) normally induced by
increasing the [K] to 10 mM was also significantly suppressed. The
replacement of 10 mM methylsulfate by Cl- restored the potassium
-induced increase in both cell volume and aldosterone secretion to
values not different from those found in the presence of 108 mM Cl-.
The potassium-induced increase in cell volume was dependent also on
the presence of extracellular calcium. Thus, a component of the
glomerulosa cell response to an increase in [K] may be caused by a
chloride-dependent increase in cell volume that is triggered by the
initial depolarization-induced increase in [Ca2+]c. The increase in
cell volume enhances the increase in [Ca2+]c and amplifies the
increase in aldosterone secretion.
Received 16 October 1995; accepted in final form 1 July 1996.
APS Manuscript Number R653-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 July 1996