Butler D G, Zhang D H
Department of Zoology, University of Toronto, Toronto, Ontario, M5S 3G5, Canada.
Gen Comp Endocrinol. 2001 Nov;124(2):199-217. doi: 10.1006/gcen.2001.7702.
Dorsal aortic blood flow (DABF) and caudal venous blood flow (CVBF) were measured in free-swimming conscious freshwater (FW) North American eels (Anguilla rostrata) with Doppler-flow probes. DABF and CVBF increased in a dose-dependent manner following iv doses of [Asn(1), Val(5), Gly(9)]-angiotensin I (ANG I), [Asn(1), Val(5)]-angiotensin II (ANG II), and [Val(4)]-angiotensin III (ANG III) ranging from 5 to 50 ng x kg bw(-1). A minimum effective dose for ANG I and ANG II was 5 ng x kg bw(-1); that for ANG III was 10 ng x kg bw(-1). DABF and CVBF rates increased during the first 2 min and remained elevated for 20-50 min. Flow responses similar to those of ANG II in form and magnitude followed iv injections of extracts of corpuscles of Stannius (CS-EXT). Increases in DABF and CVBF following injections of ANG I, human renin substrate (hRS), and CS-EXT were all blocked by the angiotensin-converting enzyme inhibitor Captopril. Increases in DABF and CVBF which followed injections of hRS and CS-EXT were blocked completely by pepstatin A. [Sar(1), Val(5)]-ANG II (Sarile) blocked completely the DABF and CVBF responses to ANG II and CS-EXT, but the mammalian receptor antagonists losartan (AT1) and PD123319 (AT2) only partially blocked them. These findings support strongly the hypothesis that the corpuscles of Stannius secrete renin or isorenin and that the renin-angiotensin system regulates cardiovascular function in freshwater eels and other bony fishes that possess them.
使用多普勒血流探头,在自由游动的清醒淡水北美鳗鱼(美洲鳗鲡)中测量背主动脉血流量(DABF)和尾静脉血流量(CVBF)。静脉注射剂量范围为5至50 ng·kg bw⁻¹的[天冬酰胺(1),缬氨酸(5),甘氨酸(9)] - 血管紧张素I(ANG I)、[天冬酰胺(1),缬氨酸(5)] - 血管紧张素II(ANG II)和[缬氨酸(4)] - 血管紧张素III(ANG III)后,DABF和CVBF呈剂量依赖性增加。ANG I和ANG II的最小有效剂量为5 ng·kg bw⁻¹;ANG III的最小有效剂量为10 ng·kg bw⁻¹。DABF和CVBF速率在最初2分钟内增加,并在20 - 50分钟内保持升高。静脉注射斯坦尼氏小体提取物(CS - EXT)后,血流反应在形式和幅度上与ANG II相似。注射ANG I、人肾素底物(hRS)和CS - EXT后DABF和CVBF的增加均被血管紧张素转换酶抑制剂卡托普利阻断。注射hRS和CS - EXT后DABF和CVBF的增加被胃蛋白酶抑制剂A完全阻断。[Sar(1),Val(5)] - ANG II(Sarile)完全阻断了DABF和CVBF对ANG II和CS - EXT的反应,但哺乳动物受体拮抗剂氯沙坦(AT1)和PD123319(AT2)仅部分阻断了它们。这些发现有力地支持了以下假设:斯坦尼氏小体分泌肾素或异肾素,并且肾素 - 血管紧张素系统调节淡水鳗鱼和其他拥有斯坦尼氏小体的硬骨鱼类的心血管功能。