DISSERTATION RESEARCH: Effects of Angiotensin II and Dehydration on Regional Blood Flows in a Terrestrial Amphibian

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Animals lose body water that must be replenished to avoid dehydration or even death. Unlike humans, amphibians, e.g. frogs and toads, have very thin skin and are susceptible to high rates of water loss. Additionally, amphibians do not drink; instead they absord water through the skin of their belly. Despite these differences, the same hormone, or chemical, in both humans and amphibians is involved in stimulating thirst. This hormone, angiotensin II, is formed when an animal becomes dehydrated. Angiotensin II is thus closely linked to thirst behavior. Angiotensin II is thus closely linked to thirst behavior. Angiotensin II has a second effect: it decreases blood flow by constricting blood vessels. Absorption of water across the skin is assumed to require increased blood flow, yet angiotensin II is known to decrease blood flow. Thus, this hormone may stimulate conflicting responses in amphibians. In amphibians as well as in humans, very little is know regarding the site where angiotensin II changes blood flows in terrestrial amphibians. Specifically, blood flow to tissues involved in water loss and water gain will be measured before and after angiotensin II injections and blockade of angiotensin II effects. The goal is to determine how an animal adapts to these apparantly conflicting effects of a single hormone. This research will add to the PIs understanding of the important role angiotensinII has played in the evolution of dehydration and rehydration behavior in animals