三羟异黄酮对失血性休克大鼠肠系膜上动脉收缩反应性的影响

目的研究三羟异黄酮(genistein,GST)对失血性休克大鼠肠系膜上动脉收缩反应性的影响及其可能机制。方法建立大鼠失血性休克(3.9kPa,2h)模型。采用离体血管环张力测定实验,观察三羟异黄酮及酪氨酸蛋白磷酸酶抑制剂钒酸钠(sodiumorthovannadate,Na3VO4)对休克大鼠肠系膜上动脉血管收缩反应性的影响;采用细胞贴附式膜片钳记录技术,观察三羟异黄酮及钒酸钠对休克大鼠肠系膜上动脉平滑肌细胞大电导钙激活钾通道(largeconductancecalciumactivatedpotassiumchannel,BKCa)活动的影响。结果失血性休克导致大鼠肠系膜上动脉对去甲肾上腺素(noradrenine,NE)的收缩反应性降低,三羟异黄酮可在一定的剂量范围内明显改善失血性休克引起的血管低反应性;钒酸钠则可引起休克血管收缩反应性的进一步降低,且该作用可被0.1mmol·L-1TEA部分阻断;进一步的研究显示,失血性休克可引起大鼠肠系膜上动脉血管平滑肌细胞BKCa通道活动的增强,三羟异黄酮可抑制休克血管平滑肌细胞BKCa通道活动,且该作用可被钒酸钠逆转。结论三羟异黄酮可通过干预由PTK介导的酪氨酸蛋白磷酸化,防止失血性休克血管平滑肌细胞BKCa通道活动的增强,从而有效恢复失血性休克大鼠肠系膜上动脉对NE的收缩反应性。

Effects of genistein on vascular hyporesponsiveness of superior mesenteric artery in hemorrhagic shock rat

Aim To study the effects of genistein on vascular hyporesponsiveness of superior mesenteric artery (SMA) in hemorrhagic shock rat and its mechanism. Methods A hemorrhagic shock model (3.9 kPa, 2 h) was established in rat. The tension measurement of artery ring in vitro was adopted to explore the effects of genistein and Na_3VO_4 (protein tyrosine phosphatase inhibitor) on the vascular responsiveness of SMA following hemorrhagic shock. The cell-attached patch clamp was adopted to elucidated the effects of genistein and Na_3VO_4 on the activity of large conductance, calcium activated potassium channel (BK_ Ca) of SMA smooth muscle cell in hemorrhagic shock rat. Results Vascular hyporesponsiveness of SMA to NE was decreased significantly in hemorrhagic shock. Genistein could improve the decreased vascular responsiveness to NE. Na_3VO_4 could induce the further decrease of vascular responsiveness to NE in hemorrhagic shock, which was partly inhibited by 0.1 mmol·L -1 TEA.Futher studys in cell-attached configuration showed that hemorrhagic shock could activate BK_ Ca of SMA smooth muscle cell.Genistein could inhibit the over-activation of BK_ Ca, while Na_3VO_4 could reverse the effects of genistein. Conclusion Genistein could prevent the BK_ Ca over-activation of SMA smooth muscle cell following hemorrhagic shock through the inhibition of protein tyrosine phosphorylation and significantly restore vascular responsiveness of SMA to NE following hemorrhagic shock in rat.