普萘洛尔对兔门静脉收缩反应的影响

EFFECT OF PROPRANOLOL ON CONTRACTION OF PORTAL VEIN IN RABBITS

本文采用离体兔门静脉环的方法,观察了普萘洛尔(Propranolol,Pro)和维拉帕米(Verapamil,Ver)对门静脉血管的作用。结果表明,Pro对兔门静脉环正常张力无影响。Pro和Ver使兔门静脉环KCl和C_αC_2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。显著抑制高K^+去极化所致门静脉环的收缩作用。此外Pro100μmol/L和Ver10μmol/L显著抑制兔门静脉条的自律性收缩,而实验证明这种收缩是钙依赖性的。提示较大剂量的Pro可能通过阻断细胞膜上电压依赖通道而发挥钙拮抗作用。

The effects of propranolol and verapamil on portal vein vessels were studied in rabbits isolated portal vein rings in this paper. The results show that propranolol have no effect on the normal tension of rabbit vein rings. Propranolol and verapamil nonparallely shifted KCl and C_aCl_2 dose-response curves to the right, decreased the maximal response, showing noncompetitive antagonism of these two kinds of curves, Propranolol inhibited the contraction of high K^+-depolarized rabbit portal vein rings. The myogenic activity of rabbit portal vein strips, which was proved to be C_a^(2+)-dependent, was also markedly inhibited by propranolol 100 μmol/L and verapamil 10 μmol/L. THe findings suggest that propranolol probably has a calcium antagonistic effect and the antagonism is carried out by blocking the potential dependent calcium channel (PDC) in the membrane of vascular smooth muscles.