低氧对苯肾上腺素诱导的豚鼠肠系膜动脉收缩反应的影响

Inhibitive effect of hypoxia on vasoconstriction of phenylephrine in mesenteric arterioles of guinea pig

目的：探讨不同时段低氧对苯肾上腺素（phenylephrine,PE）诱导的豚鼠肠系膜动脉收缩反应的影响及其作用机制。方法：应用压力肌动图技术,在急性分离的豚鼠肠系膜动脉2级血管（直径300~400μm）上,观察20、40和60 min低氧（95%CO2和5%O2混合）对内皮非依赖的血管收缩剂PE收缩血管直径的影响。结果：PE（0.1~100μmol/L）可以浓度依赖性收缩豚鼠肠系膜动脉。低氧引起生理盐溶液p H值从7.4下降到6.3。低氧能显著抑制PE引起的血管收缩幅度,用正常生理盐溶液洗脱20 min此抑制作用仍难以恢复。低氧抑制PE引起的肠系膜动脉的收缩反应具有时间依赖性,抑制程度依次为低氧60 min〉40min〉20 min。将生理盐溶液p H降低至6.3也可抑制PE对血管收缩的作用。结论 ：低氧能够时间依赖性地抑制PE对豚鼠肠系膜动脉的收缩作用,其作用机制可能与p H的下降有关。

Objective To investigate the effects and mechanisms of hypoxia on the contraction of mesenteric arteries induced by phenylephrine（PE） in guinea pig. Methods Pressure myograph system was used to study the effects of 20, 40 and 60 min hypoxia（mixed with 95% CO2 and 5% O2） on the constriction induced by PE in acutely separated mesenteric artery（300 ~ 400 μm） of guinea pig. Results PE（0.1 ~ 100 μmol / L）caused the contractions of the mesenteric arteries in guinea pig in a concentration- dependent way. Hypoxia de creased the p H value of perfusion fluid from 7.4 to 6.3. Hypoxia significantly inhibited PE-induced vasoconstriction, and the inhibition was hard to recover after reoxygenation. Hypoxia inhibited PE-induced vasoconstriction in a time-dependent way, with the inhibition rate reduced in the sequence of inhibition duration of 60, 40 and 20 min. When its value was decreased to 6.3, the perfusion fluid even inhibited PE-induced vasoconstric tion. Conclusion Hypoxia can inhibit PE-induced vasoconstriction in the mesenteric arteries of guinea pig in a time-dependent way. The mechanism may have something to do with the change of pH.