Angiotensin-related intakes of water and NaCl in Fischer 344 and Sprague-Dawley rats

Abstract

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.