Inhibition of Cutaneous Water Absorption in Dehydrated Toads by Saralasin Is Associated with Changes in Barometric Pressure

Abstract

The effects of the angiotensin II (AII) antagonist, saralasin, on the rehydration behavior of dehydrated toads (Bufo punctatus) were examined during periods of (1) rising or steady and (2) falling barometric pressure. When allowed to rebydrate during periods of rising or steady barometric pressure, Ringer's-treated (control) toads returned to their pretest (ad lib.) weight, while saralasin-treated toads terminated water-absorption-response (WR) behavior before regaining their ad lib. weight. When the barometric pressure was falling the pattern of WR behavior and weight gain was reversed: control toads failed to regain their ad lib. weight, while saralasin-treated toads did regain their ad lib. weight. The rates of water gain were the same for all treatment groups, indicating that the changes in water gain were due to the time spent in the WR. The results of this study suggest that endogenous All is involved in the regulation of WR behavior in B. punctatus and that WR behavior is also modulated by climatic factors that might affect the availability of water.