Relative Antidipsogenic Potencies of Six Homologous Natriuretic Peptides in Eels
Relative Antidipsogenic Potencies of Six Homologous Natriuretic Peptides in Eels
复制标题
鳗鱼中六种同源利尿钠肽的相对抗体力效力
作者：
Hiroshi Miyanishi;Shigenori Nobata;Y. Takei
心房利钠肽(ANP)在鳗鱼体内表现出很强的抗高血压作用，可以限制过量的Na+摄取，从而有效地促进海水鳗鱼的适应。最近，在鳗鱼中发现了心脏ANP、BNP和VNP以及脑CNP1、3和4。我们在FW和SW中使用清醒的空腹鳗鱼以及影响饮酒的参数来检验所有同源NPs的抗糖尿病作用。对黄鳗的剂量-反应研究(0.01-1nmol/kg)表明，抗高血压作用的相对效力顺序为：ANP≥VNP>；BNP=CNP3>；CNP1CNP4；对血管降压作用的顺序为ANP=VNP=BNP>；CNP3=CNP1=CNP4。ANP抗糖尿病作用的最小有效剂量远低于哺乳动物。0.3nmol/kg的ANP、BNP和VNP可降低鳗鱼的饮水量、血浆Na+浓度和主动脉压，增加红细胞压积。心脏NPs对黄鳗的饮水量、主动脉压和红细胞压积有相似的影响，但对血浆Na+浓度无明显影响。CNP3对黄鳗的饮水量、血浆Na+浓度和红细胞压积均无影响，但对黄鳗和黄鳗均有轻度降压作用，但CNP3对黄鳗的饮酒有抑制作用。这些结果表明，尽管存在其他诱导饮酒的调节因素，但ANP、BNP和VNP是鳗鱼体内有效的抗糖尿病激素，而CNP除了心脏NPs的祖先CNP3外，对饮酒没有影响。
Atrial natriuretic peptide (ANP) exhibits a potent antidipsogenic effect in seawater (SW) eels to limit excess Na+ uptake, thereby effectively promoting SW adaptation. Recently, cardiac ANP, BNP and VNP and brain CNP1, 3 and 4, have been identified in eels. We examined the antidipsogenic effect of all homologous NPs using conscious, cannulated eels in both FW and SW together with parameters that affect drinking. A dose-response study (0.01–1 nmol/kg) in SW eels showed the relative potency of the antidipsogenic effect was in the order ANP ≥ VNP > BNP = CNP3 > CNP1 ≥ CNP4, while the order was ANP = VNP = BNP > CNP3 = CNP1 = CNP4 for the vasodepressor effect. The minimum effective dose of ANP for the antidipsogenic effect is much lower than that in mammals. ANP, BNP and VNP at 0.3 nmol/kg decreased drinking, plasma Na+ concentration and aortic pressure and increased hematocrit in SW eels. The cardiac NPs induced similar changes in drinking, aortic pressure and hematocrit in FW eels, but aside from BNP no change in plasma Na+ concentration. CNPs had no effect on drinking, plasma Na+ concentration and hematocrit but induced mild hypotension in both FW and SW eels, except for CNP3 that inhibited drinking in SW eels. These results show that ANP, BNP and VNP are potent antidipsogenic hormones in eels in spite of other regulatory factors working to induce drinking, and that CNPs are without effects on drinking except for the ancestor of the cardiac NPs, CNP3.