AJP - Regulatory, Integrative and Comparative Physiology, Vol 239, Issue 1 156-R160, Copyright © 1980 by American Physiological Society
Renal and peripheral vascular responsiveness to arginine vasotocin in bullfrog, Rana catesbeiana
P. K. Pang, S. M. Galli-Gallardo, N. Collie and W. H. Sawyer
Arginine vasotocin (AVT), the amphibian neurohypophysial hormone, has
pressor and antidiuretic actions in bullfrogs (Rana catesbeiana). Much
higher doses of exogenous AVT were required for the pressor response than
those for the antidiuretic response. When bullfrog legs and kidneys were
perfused under constant pressure simultaneously, the kidney vasculature was
more sensitive to bolus injection of AVT than was the leg vasculature. The
same was true when the tissues were perfused with different concentrations
of hormone. AVT constricts preglomerular vessels in the bullfrog. We
suggest that the preglomerular vasculature of the bullfrog is more
sensitive to AVT than is the peripheral vasculature. This may explain in
part the antidiuretic action of the hormone at nonpressor doses.
Evolutionary speculations are discussed.
