普萘洛尔对兔门静脉平滑肌细胞电压依赖性钙通道的抑制作用

Inhibitory effect of propranolol on the voltage dependent calcium channel in the membrane of vascular smooth muscles of portal vein in rabbits

目的 探讨普萘洛尔 (propranolol,Pro)降低门脉压和对门静脉血管平滑肌的作用机制。方法 采用离体兔门静脉平滑肌实验方法 ,观察Pro对门静脉平滑肌张力、自发性节律性收缩及CaCl2 、KCl、高K+ 去极化收缩的影响。结果 Pro对兔门静脉环正常张力无影响 ;Pro 10 0 μmol·L-1和维拉帕米 (verapamil,Ver) 10 μmol·L-1显著抑制兔门静脉的自律性收缩 ;Pro和Ver使兔门静脉环KCl和CaCl2 量效曲线非平行右移 ,最大反应压低 ,显示非竞争性拮抗的两种曲线 ;Pro显著抑制高K+ 去极化所致门静脉环的收缩作用。结论 较大剂量的Pro可能通过阻断血管平滑肌细胞膜上电压依赖性钙通道 (VDC)

Objective To investigate the effects of propranolol on portal vein smooth muscle and its mechanism of decreasing the portal vein pressure.Methods The effects of propranolol on tension of smooth musle of portal vein,auto-rhythmicity contraction,CaCl 2, KCl and the contraction of high K +-depolarized were observed in isolated portal vein smooth muscle from rabbits.Results The propranolol haven't affects on the normal tension of rabbit vein rings;The automaticity contraction of portal vein strips,which was proved to be Ca 2+ -dependent,was markedly inhibited by propranolol 100?μmol·L -1 and verapamil 10?μmol·L -1 .Propranolol and verapamil nonparallely shifted KCl and CaCl 2 dose-response curves to the right,decreased the maximal response,and showing noncompetitive antagonism of these two kinds of curves.The propranolol inhibited the contraction of high K +-depolarized rabbit portal vein rings.Conclusion Propranolol probably has a calcium antagonistic effect and the antagonism is carried out by blocking the voltage dependent calcium channel (VDC) in the membrane of vascular smooth muscles cells.