Silldorff E P, Stephens G A
School of Life and Health Sciences, University of Delaware, Newark 19716.
Gen Comp Endocrinol. 1992 Jul;87(1):141-8. doi: 10.1016/0016-6480(92)90160-l.
We examined the pressor response to exogenous, nonnative angiotensin I (ANG I; bullfrog, turtle, and fowl) in the conscious American alligator, Alligator mississippiensis. In addition, the inhibitory effects of three ANG II analogues ([Sar1, Ala8], [Sar1, Thr8], and [Sar1, Ile8]ANG II) on the pressor responses to angiotensin I (fowl ANG I, [Asp1, Val5, Ser9]) were also examined. Intravenous administration of bullfrog, turtle, and fowl ANG I at 0.1, 0.5, and 1.0 micrograms/kg produced dose-dependent increases in arterial blood pressure. [Val5]ANG II at 0.05, 0.1, and 0.5 micrograms/kg, or NE at 2 micrograms/kg also produced dose-dependent increases in blood pressure. [Sar1, Ile8]ANG II and [Sar1, Ala8]ANG II (10 micrograms/kg/min) both attenuated the pressor response to fowl ANG I whereas [Sar1, Thr8]ANG II (10 micrograms/kg/min) produced no significant blockade. These data demonstrate: (1) All three exogenous ANG I molecules exert potent vasopressor responses in the alligator, (2) [Sar1, Ile8]ANG II is the most effective ANG antagonist, and (3) the alligator appears to possess a renin-angiotensin system similar to that found in other vertebrates.
我们研究了有意识的美国短吻鳄（密西西比鳄）对外源性非天然血管紧张素I（ANG I；牛蛙、乌龟和家禽来源）的升压反应。此外，还研究了三种血管紧张素II类似物（[Sar1, Ala8]、[Sar1, Thr8]和[Sar1, Ile8]ANG II）对血管紧张素I（家禽ANG I，[Asp1, Val5, Ser9]）升压反应的抑制作用。静脉注射0.1、0.5和1.0微克/千克的牛蛙、乌龟和家禽ANG I可使动脉血压呈剂量依赖性升高。0.05、0.1和0.5微克/千克的[Val5]ANG II或2微克/千克的去甲肾上腺素（NE）也可使血压呈剂量依赖性升高。[Sar1, Ile8]ANG II和[Sar1, Ala8]ANG II（10微克/千克/分钟）均减弱了对家禽ANG I的升压反应，而[Sar1, Thr8]ANG II（10微克/千克/分钟）未产生明显的阻断作用。这些数据表明：（1）所有三种外源性ANG I分子在短吻鳄中均发挥强大的血管升压反应；（2）[Sar1, Ile8]ANG II是最有效的ANG拮抗剂；（3）短吻鳄似乎拥有与其他脊椎动物相似的肾素-血管紧张素系统。
