Olson K R, Villa J
Indiana University School of Medicine, South Bend Center, University of NoTre Dame 46556.
Am J Physiol. 1991 May;260(5 Pt 2):R925-33. doi: 10.1152/ajpregu.1991.260.5.R925.
Bradykinin (BK)- or acetylcholine (ACh)-mediated vasodilation has only rarely been observed in fish. This suggests that many fish vessels lack the endothelium-dependent relaxing mechanisms recently identified in mammals. To examine this hypothesis, isolated vascular rings were prepared from trout ventral aortas (VA), efferent branchial and celiacomesenteric (CM) arteries, and anterior cardinal veins (CV) and examined for endothelium-mediated responses. A doubly perfused trunk preparation was also used to evaluate the response of the microcirculation. ACh produced dose-dependent contractions in all vascular rings and increased vascular resistance when perfused into the CM but had no affect when perfused into the dorsal aorta. Neither ACh nor BK relaxed precontracted vessels or lowered resting tone. Removal of the endothelium did not affect ACh or BK responses. The calcium ionophore A23187 produced an endothelium-dependent relaxation of precontracted VA, CM, and CV. The A23187 response was abolished by indomethacin, indicating that a prostanoid was involved in the relaxation. ATP contracted and/or relaxed precontracted CM and CV. ATP effects were independent of an intact endothelium. Sodium nitroprusside and atrial natriuretic factor partially or completely relaxed all vessels, indicating the presence of soluble and particulate guanylate cyclases, respectively. These results suggest that nonprostanoid endothelium-derived relaxing factors (EDRFs) or EDRF-like vasodilator mechanisms are not present in trout vessels or, if they are, they are not released by classical agonists.
缓激肽（BK）或乙酰胆碱（ACh）介导的血管舒张在鱼类中很少被观察到。这表明许多鱼类血管缺乏最近在哺乳动物中发现的内皮依赖性舒张机制。为了验证这一假设，从虹鳟鱼的腹主动脉（VA）、鳃出动脉和腹腔肠系膜（CM）动脉以及前主静脉（CV）制备了离体血管环，并检测其内皮介导的反应。还使用了双灌注躯干标本评估微循环的反应。ACh在所有血管环中产生剂量依赖性收缩，灌注到CM时增加血管阻力，但灌注到背主动脉时无影响。ACh和BK均不能舒张预收缩的血管或降低静息张力。去除内皮不影响ACh或BK的反应。钙离子载体A23187使预收缩的VA、CM和CV产生内皮依赖性舒张。吲哚美辛消除了A23187的反应，表明一种前列腺素参与了舒张过程。ATP使预收缩的CM和CV收缩和/或舒张。ATP的作用不依赖于完整的内皮。硝普钠和心房利钠因子分别使所有血管部分或完全舒张，表明分别存在可溶性和颗粒性鸟苷酸环化酶。这些结果表明，虹鳟鱼血管中不存在非前列腺素类内皮源性舒张因子（EDRFs）或类似EDRF的血管舒张机制，或者即使存在，它们也不会被经典激动剂释放。
