AJP - Regulatory, Integrative and Comparative Physiology, Vol 262, Issue 3 382-R388, Copyright © 1992 by American Physiological Society
Angiotensin-related intakes of water and NaCl in Fischer 344 and Sprague-Dawley rats
F. A. Caputo, N. E. Rowland and M. J. Fregly
Department of Psychology, University of Florida, Gainesville 32611.
Rats of the Fischer 344 (F344) strain drank less water after either
peripheral or central acute administration of angiotensin III (ANG III)
than rats of the Sprague-Dawley (SD) strain. In contrast, water intakes
following acute administration of ANG II were comparable in the two
strains. Chronic peripheral administration of ANG II produced a salt
appetite in SD but not in F344 rats; ANG III was ineffective in both
strains. These data suggest that some aspects of responsiveness to ANG
peptides are reduced in F344 rats. In two of three studies, water intake
after acute peripheral administration of either ANG I or the
beta-adrenergic agonist isoproterenol did not differ between strains; in
one study, the response to both dipsogens was lower in F344 rats. Plasma
renin activity was elevated to the same level by isoproterenol in both
strains of rats. These results suggest that the ability of isoproterenol to
release renin, the subsequent generation of ANG I, and the conversion to
ANG II are similar in the two strains. However, this similarity did not
extend to cardiovascular responses. Rats of the F344 strain showed a
smaller decrease in blood pressure following administration of
isoproterenol than did those of the SD strain. Whether this is related to
differences in either the regulation of beta-adrenoreceptors or
postreceptor effects in vascular smooth muscle between strains will require
additional investigation.
