AJP - Regulatory, Integrative and Comparative Physiology, Vol 253, Issue 1 20-R24, Copyright © 1987 by American Physiological Society
Concentration of adrenocortical hormones in relation to cation homeostasis in birds
J. Rosenberg and S. Hurwitz
The effects of dietary Na+, K+, and Cl- and of acute stress on plasma
levels of Na+, K+, aldosterone, and corticosterone were evaluated in vivo
in birds. The dietary effects were studied in growing White Rock chicks,
whereas the larger turkey was preferred for the acute stress study.
Although plasma corticosterone remained unaffected, plasma aldosterone
concentration decreased with increasing levels of dietary Na+ reaching a
minimum at a dietary level of 72 meq/kg. Plasma Na+ remained unchanged when
dietary Na+ levels increased up to 72 meq/kg but then rose with increasing
Na+ intake. Plasma K+ was slightly depressed by high levels of dietary Na+
and increased by dietary K+. Neither plasma Na+ nor circulating adrenal
hormones were affected by dietary K+ or dietary Cl-. Acute stress
stimulated both aldosterone and corticosterone without any effect on the
levels of the plasma minerals. The results suggest that of the two main
corticoids, only aldosterone responds to dietary Na+ in chicks. This is in
contrast to the indiscriminate stimulation of both hormones by stress,
indicating different pathways of stimulation. The results also suggest that
aldosterone is involved in the regulation of plasma Na+ only at low intakes
of Na+ and that dietary K+ and Cl- are not involved in the aldosterone-Na+
feedback relationship.
