THE EFFECTS OF VALATILE ANESTHETICS ON VASCULAR SMOOTH MUSCLE

本研究旨在探讨挥发性麻醉药对离体犬肠系膜动、静脉的作用。方法;实验在戊巴比妥钠（25 mg/kg，IV.）麻醉的杂种犬（7- 20 kg）的离体肠系膜动、静脉上进行。解剖血管周围脂肪和结缔组织后，将动脉和静脉切成环，将其悬挂在充满Krebs-Ringer溶液（20 ml）的器官浴室中用于等长张力测量。本文观察了氟烷、异氟烷和七氟烷对去甲肾上腺素（NE，10 <-8>~ 10 μ <-3>M）、酪胺（Tyr，10 <-8>~ 10 μ <-3>M）和电场刺激（ES ; 9V，2 ms，1- 32 Hz）引起的张力发展的影响。挥发性麻醉药从蒸发器输送到O_2 -CO_2混合气中。通过麻醉气体分析仪连续监测所得气体混合物中的浓度。结果：氟烷、异氟醚和七氟醚在1、2 MAC浓度下对血管环基础张力无明显影响。氟烷、异氟醚和七氟醚对ES引起的静脉环最大收缩作用的减弱程度相同。氟烷、异氟烷和七氟烷对Tyr引起的动脉和静脉收缩均无抑制作用。氟烷和异氟醚，但不是七氟醚，衰减NE在肠系膜静脉的最大收缩。结论;上述结果提示：（1）氟烷、异氟醚和七氟醚可抑制肠系膜静脉交感神经末梢释放Ca^2+依赖性NE。(2)氟烷和异氟烷抑制α-肾上腺素受体介导的肠系膜静脉血管平滑肌收缩。

This study was designed to investigate the effects of volatile anesthetics on isolated canine mesenteric artery and vein. Method ; The experiments were performed on isolated mesenteric arteries and veins from mongrel dogs (7-20kg) anesthetized with sodium pentobarbital (25mg/kg, IV.). After the perivascular fat and connective tissue were dissected away, artery and vein were cut into rings which were suspended into organ bath chamber filled with Krebs-Ringer solution (20ml) for isometric tension measurements. Effects of halothane, isoflurane and sevoflurane on tension development induced by norepinephrine (NE,10^<-8>-10^<-3>M), tyramine (Tyr, 10^<-8>-10^<-3>M) and electrical field stimulation (ES ; 9V,2ms, 1-32Hz) were investigated. Volatile anesthetics were delivered from a vaporizer into the O_2 -CO_2 mixture aerating bathing media. The concentration in the resulting gas mixture was monitored continuously by an anesthetic gas analyzer. Results ; In concentration (1,2MAC) used, halothane, isoflurane and sevoflurane did not effect basal tension of blood vessel rings. However, halothane, isoflurane and sevoflurane attenuated ES induced maximum contraction of vein rings by same extend. Halothane, isoflurane and sevoflurane did not inhibited Tyr induced contraction in both artery and vein. Halothane and isoflurane but not sevoflurane, attenuated maximum contraction by NE in mesenteric vein. Conclution ; These results suggested that (1) halothane, isoflurane and sevoflurane may inhibit Ca^<2+>-dependent NE release from sympathetic nerve endings of mesenteric vein. (2) halothane and isoflurane inhibit alpha-adrenoceptor mediated vascular smooth muscle contraction of mesenteric vein.