Structural and Funtional Characterization of Bradykinin Receptors in Teleost Fish

9806997 Conlon Brandykinin（BK）在哺乳动物中的作用是通过与称为B1和B2的离散受体相互作用来介导的。 在硬骨鱼、虹鳟鱼和大西洋鳕鱼中激活激肽释放酶-激肽系统产生（Arg 0，Trp 5，Leu 8）-BK（鳟鱼/鳕鱼BK）。 这种肽对这些物种的胃肠平滑肌运动和血压的影响是通过彼此不同的受体以及与哺乳动物B1和B2受体不同的受体介导的。 建议通过从鳟鱼肠道cDNA文库和鳕鱼基因组文库中克隆BK受体并对其结构进行表征来深入了解BK受体的进化。 鳟鱼/鳕鱼BK的结构-活性关系将通过合成类似物来研究，其中肽中的每个氨基酸残基已被丙氨酸或其D-异构体系统地取代。 测定取代对（a）用克隆的鳟鱼和鳕鱼BK受体瞬时转染的培养的哺乳动物细胞的受体结合特性，（B）未麻醉鳕鱼的动脉血压升高，和（c）鳟鱼胃和鳕鱼肠的运动性的影响。 将开发鳟鱼和鳕鱼BK受体的拮抗剂，并在这些生物测定中评价其特性。 将研究鳟鱼/鳕鱼BK对鳟鱼胃分离粘膜的胃酸和胃蛋白酶原分泌、离体鳟鱼肠中的电解质转运以及鳟鱼肾脏的尿液产生的影响。 两者合计，这些数据将提供深入了解的“祖先”BK受体的哺乳动物受体可能已经演变的属性，并将导致更好地了解的激肽释放酶-激肽系统在硬骨鱼的生理作用。

9806997 Conlon The effects of brandykinin (BK) in mammals are mediated through interaction with discrete receptors, termed B1 and B2. Activation of the kallikrein-kinin system in the teleost fish, rainbow trout and Atlantic cod generates (Arg0,Trp5,Leu8)-BK (trout/cod BK). The effects of this peptide on the motility of gastrointestinal smooth muscle and on blood pressure in these species are mediated via receptors that are pharmacologically different from each other and from mammalian B1 and B2 receptors. It is proposed to gain insight into BK receptor evolution by cloning BK receptors from a trout intestinal cDNA library and a cod genomic library and characterizing them structurally. Structure-activity relationships of trout/cod BK will be investigated by synthesizing analogs in which each amino acid residue in the peptide has been systematically replaced either by alanine or by its D-isomer. The effect of the substitutions on (a) receptor-binding properties using cultured mammalian cells that have been transiently transfected with the cloned trout and cod BK receptors, (b) elevation of arterial blood pressure in the unanesthetized cod, and (c) motility of trout stomach and cod intestine will be determined. Antagonists to the trout and cod BK receptors will be developed and their properties evaluated in these bioassays. The effect of trout/cod BK on gastric acid and pepsinogen secretion by isolated mucosa from trout stomach, electrolyte transport in the isolated trout intestine and on urine production by the trout kidney will be studied. Taken together, the data will provide insight into the properties of "ancestral" BK receptor from which the mammalian receptors may have evolved and will lead to a greater understanding of the physiological role of the kallikrein-kinin system in teleost fish.