Nishimura H, Norton V M, Bumpus F M
Am J Physiol. 1978 Jul;235(1):H95-103. doi: 10.1152/ajpheart.1978.235.1.H95.
Synthetic angiotensins I and II (AI and AII) and natural eel angiotensin were injected with angiotensin antagonists into freshwater-adapted, unanesthetized American eels, Anguilla rostrata, in an attempt to characterize the vasopressor properties of angiotensins in a primitive vertebrate. A converting enzyme inhibitor, SQ 20,881, inhibited vasopressor responses to eel angiotensin (presumably AI) and [Val5,Ser9]AI, but not those to [Asn1,Val5]AII, suggesting that a converting enzyme-like substance may exist in eels. [Sar1,Thr8]AII (10 microgram/kg per min) and [Sar1,Ile8]AII (1 microgram/kg per min), which antagonize angiotensin's action in mammals, showed neither agonistic vasopressor nor antagonistic effects in eels against [Asn1,Val5]AII or eel angiotensin. [Tal8]AII ([8-thienylalanine]AII) and a higher dose of [Sar1,Ile8]AII increased eel aortic pressure themselves and reduced vasopressor responses to [Asn1,Val5]AII. This is presumably a nonspecific decrease in response during the agonistic phase of the analogs. Angiotensin receptors in the blood vessels of eels may differ from those in mammals. Alpha-adrenergic blocking drugs and reserpine partially inhibited the pressor effect of [Asn1,Val5]AII in eels.
将合成血管紧张素I和II（AI和AII）以及天然鳗鱼血管紧张素与血管紧张素拮抗剂一起注射到适应淡水、未麻醉的美洲鳗鲡（Anguilla rostrata）体内，试图表征原始脊椎动物中血管紧张素的血管升压特性。一种转化酶抑制剂SQ 20881抑制了对鳗鱼血管紧张素（可能是AI）和[Val5，Ser9]AI的血管升压反应，但对[Asn1，Val5]AII的反应没有抑制作用，这表明鳗鱼体内可能存在一种类似转化酶的物质。在哺乳动物中拮抗血管紧张素作用的[Sar1，Thr8]AII（每分钟10微克/千克）和[Sar1，Ile8]AII（每分钟1微克/千克），对鳗鱼体内的[Asn1，Val5]AII或鳗鱼血管紧张素既没有激动性血管升压作用也没有拮抗作用。[Tal8]AII（[8-噻吩丙氨酸]AII）和更高剂量的[Sar1，Ile8]AII本身会升高鳗鱼主动脉压力，并降低对[Asn1，Val5]AII的血管升压反应。这可能是类似物激动期反应的非特异性降低。鳗鱼血管中的血管紧张素受体可能与哺乳动物中的不同。α-肾上腺素能阻断药物和利血平部分抑制了[Asn1，Val5]AII对鳗鱼的升压作用。
