Structural and Funtional Characterization of Bradykinin Receptors in Teleost Fish

9806997结论Brandykinin(BK)在哺乳动物中的作用是通过与离散的受体B1和B2相互作用而实现的。硬骨鱼、虹鲑鱼和大西洋鳕鱼中激肽释放酶-激肽释放酶系统的激活产生(Arg0，Trp5，Leu8)-BK(鲑鱼/鳕鱼BK)。在这些物种中，这种多肽对胃肠平滑肌的运动和对血压的影响是通过不同的受体介导的，这些受体在药理上是不同的，也不同于哺乳动物的B1和B2受体。通过从鲑鱼肠道cDNA文库和鳕鱼基因组文库中克隆BK受体并对它们进行结构鉴定，可以深入了解BK受体的进化。鲑鱼/鳕鱼BK的构效关系将通过合成类似物来研究，在类似物中，肽中的每个氨基酸残基都被丙氨酸或其D-异构体系统地取代。这些替换对(A)瞬时转导克隆的鲑鱼和鳕鱼BK受体的培养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以及(C)鲑鱼胃和鳕鱼肠道的运动的影响将被确定。将开发鲑鱼和鳕鱼BK受体的拮抗剂，并在这些生物检测中评估它们的特性。研究了鲑鱼/鳕鱼BK对离体鱼胃粘膜胃酸和胃蛋白酶原分泌的影响，以及对离体肠电解质转运和肾排尿的影响。综上所述，这些数据将提供对哺乳动物受体进化而来的“祖先”BK受体的特性的洞察，并将有助于更好地理解激肽释放酶-激动素系统在硬骨鱼中的生理作用。

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.