AJP - Regulatory, Integrative and Comparative Physiology, Vol 250, Issue 6 1034-R1038, Copyright © 1986 by American Physiological Society
Angiotensin-stimulated drinking in marine fish
D. Beasley, D. N. Shier, R. L. Malvin and G. Smith
Drinking rates in both marine and freshwater stenohaline fish were studied
by measuring the ingestion of polyethylene glycol that had been added to
the aquarium water. Two marine species, the long-horned sculpin and the
flounder, and three freshwater species, the common goldfish, the mottled
sculpin, and the common shiner, were used. Control drinking rates in
freshwater fish averaged 0.03-0.1% body wt/h and in marine fish varied
between 0.06 and 0.24% body wt/h. Intramuscular injections of angiotensin
II (ANG II) stimulated drinking two- to threefold in the two marine species
but had no effect on the drinking rate of the freshwater species.
Hemorrhage (1-2% of body wt) also stimulated drinking in the two marine
species (6- to 10-fold) but did not affect the drinking rate of two
freshwater species. Thus exogenous ANG II and hemorrhage stimulate drinking
in two marine stenohaline fish as they do in mammals. These responses were
absent in the three freshwater fishes studied. However, injection of
converting enzyme inhibitor (SQ 20881) or saralasin in order to block
endogenous ANG II did not attenuate either basal or hemorrhage-stimulated
drinking in the marine fish.
