The Integrative Aspects of Fluid and Electrolyte Balance in Birds

这项拟议的研究是对鸟类体液和电解质平衡的综合方面的研究。由于没有膀胱，鸟类的尿会进入胃肠道的末端，即泄殖腔。尿液不会留在这里，而是沿口腔方向进入直肠，在那里它与能够主动运输的上皮组织接触。因此，创造了可以改变尿液成分的条件。由于这种解剖和功能关系，鸟类的肾脏并不像哺乳动物那样唯一控制液体和电解质的平衡。在这份提案中，我计划研究这个系统的几个组件。这些是：1)对控制尿液从泄殖腔进入肠道的因素的调查。这种运动是一直都会发生的，还是会随着尿液的成分和体积而变化？如果它确实不同，什么参数是敏感的，它们是如何被检测到的？2)对鸟类肾脏的浓缩机制的研究。是什么限制了鸟肾浓缩尿液的能力？通常，与哺乳动物的肾脏相比，鸟类的肾脏不能很好地浓缩尿液。3)鸟类尿液中尿酸与蛋白质结合的研究。鸟类尿液中的尿酸浓度大大超过了这种化合物的溶解度极限。尿酸与蛋白质(糖蛋白)的结合阻止了晶体的形成。这种蛋白质是从哪里来的，它是如何结合尿酸的？家禽将被用作实验动物，以产生数据来检验这一提议的假设。这项拟议的研究产生的数据将有助于更好地理解体液和电解质平衡的调节，并有助于纠正对鸟类渗透调节的一些误解。

The proposed research is a study of the integrative aspects of fluid and electrolyte balance in birds. Because of the lack of a urinary bladder, the urine of birds enters the terminal portion of the gastrointestinal tract, the cloaca. The urine does not remain here, but moves in an oral direction into the rectum where it comes into contact with epithelial tissues capable of active transport. Thus, conditions are created under which the composition of the urine can be modified. Because of this anatomical and functional relationship, the kidneys of birds do not have sole control of fluid and electrolyte balance, as is the case for mammals. In this proposal, I plan to investigate several components of this system. These are: 1) An investigation of the factors that control the movement of urine from the cloaca into the intestine. Does this movement occur at all times, or does it vary with the composition and volume of the urine? If it does vary, what parameters are sensed and how are they detected? 2) An investigation of the concentrating mechanism of the bird kidney. What limits the capacity of the bird kidney to concentrate the urine? Typically, the kidneys of birds do not concentrate the urine well when compared to those of mammals. 3) An investigation of binding of uric acid to proteins in the urine of birds. The concentration of uric acid in the urine of birds greatly exceeds the solubility limits for this compound. Crystal formation is prevented by the binding of uric acid to a protein (glycoprotein). Where does this protein come from and how does it bind uric acid? Domestic fowl (Gallus domesticus) are to be used as experimental animals to generate data to test the hypothesis of this proposal. Data generated by the proposed research will lead to a better understanding of the regulation of fluid and electrolyte balance and should help to correct some of the misconceptions about avian osmoregulation.//