Integration of Water and Energy Balance in Hummingbirds

蜂鸟的高代谢主要是由花蜜中的糖提供能量，但与糖一起消耗的是多余的水，每天可以达到鸟自己体重的几倍。在蜂鸟中，肾脏和胃肠道在水、电解质和能量平衡的调节中发挥着协调的作用。Beuchat描述了一系列的实验，包括GFR和肾管水重吸收的测量，以及肠道水和葡萄糖吸收的测量，这些实验将分离出蜂鸟调节能量、水和电解质平衡的机制的基本组成部分。该项目的重点是蜂鸟的基本肾脏功能和肾脏与肠道功能的整合，将为这些动物的生理学提供基础信息。从更广泛的角度来看，这项研究将是第一次仔细研究鸟类或哺乳动物的渗透调节生理学，它们是研究慢性利尿的模式生物。最后，本研究将首次在体内验证由Na+偶联葡萄糖运输激活的细胞旁液通量在脊椎动物的营养摄取中发挥重要作用的假设。

The high metabolism of hummingbirds is fueled principally by the sugar found in nectar, but consumed along with the sugar is an excess of water that can amount to several time the bird's own body mass per day. In hummingbirds, the kidney and the gastrointestinal tract mush consequently play coordinated roles in the regulation of water, electrolyte, and energy balance. Beuchat describes a series of experiments, including measurements of GFR and tubular water reabsorption in the kidney, and of water and glucose absorption in the intestine, that will isolate fundamental components of the mechanisms hummingbirds use to regulate energy, water, and electrolyte balance. The project's focus on basic kidney function and on the integration of renal with intestinal function in hummingbirds will provide fundamental information about the physiology of these animals. In a broader perspective, this study will be the first to closely examine the osmoregulatory physiology of a bird or mammal that is a model organism for the study of chronic diuresis. Finally, this study will be first in vivo test of the hypothesis that paracellular fluid flux activated by Na+- coupled glucose transport can play a significant role in nutrient uptake in vertebrates.