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

动物失去了体内的水分，必须补充，以避免脱水甚至死亡。与人类不同，两栖动物，如青蛙和蟾蜍，皮肤很薄，容易失水。此外，两栖动物不喝水；相反，它们通过腹部的皮肤吸收水分。尽管存在这些差异，但人类和两栖动物体内同样的激素或化学物质参与刺激口渴。这种激素，血管紧张素II，是在动物脱水时形成的。因此，血管紧张素II与口渴行为密切相关。因此，血管紧张素II与口渴行为密切相关。血管紧张素II还有第二个作用：它通过收缩血管来减少血流量。人们认为皮肤吸收水分需要增加血流量，然而血管紧张素II可以减少血流量。因此，这种激素可能会刺激两栖动物产生相互矛盾的反应。在两栖动物和人类中，关于血管紧张素II改变陆生两栖动物血流的位置，我们所知甚少。具体来说，在注射血管紧张素II和阻断血管紧张素II的作用前后，将测量与水分流失和水分增加有关的组织的血流量。目的是确定动物如何适应单一激素的这些明显相互冲突的影响。这项研究将增加pi对血管紧张素i在动物脱水和补液行为进化中的重要作用的理解

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