The comparative study of the effect of abnormal hemodynamics on the functions of endothelial and smooth muscle cells of arterially transplanted autologous vein grafts.

根据我们以前的报道，血管搭桥术的结果与术中电磁决定的血流波形密切相关，决定血管通畅性的一个重要因素是一个心动周期内的切应力变化。在此基础上，我们利用犬后肢远端流出不良模型，研究了血流动力学异常(低切应力)对股动脉内皮细胞和血管内皮细胞及自体静脉移植的影响。结果发现：1)在血流异常(低切应力)的情况下，股动脉和自体静脉移植物的内皮细胞产生PGI2的速率明显低于正常血流条件下的水平。2)乙酰胆碱引起对照静脉内皮依赖性松弛，而移植静脉3天后未见血管内皮依赖性松弛。3)在血流异常(低切应力)条件下，ADP或凝血酶引起的股动脉和自体静脉移植物内皮依赖性松弛受到选择性干扰。4)5-羟色胺(5-羟色胺)在对照静脉引起内皮依赖性松弛，而在自体静脉移植物引起显著收缩。这些结果提示，在血流异常(低切应力)的情况下，PGI2的产生减少，以及在动脉血流的情况下，自体静脉移植物内皮依赖性松弛的选择性丧失是导致自体静脉移植物晚期失败的重要因素。

On the basis of our previous reports that the outcome of the bypass grafts was closely associated with the electromagnetically determined flow waveform pattern at operation and an essential factor in determining patency was the shear stress variation in one cardiac cycle, we studied the effect of abnormal flow hemodynamics (low shear stress) on the functions of endothelial and smooth muscle cells of femoral arteries and of arterially transplanted autologous vein graft using a canine poor distal runoff model in hind limbs. As a result, we obtained some findings as follows: 1)Production rate of PGI2 from the endothelial cells of femoral artery and autovein graft strikingly decreased under conditions of abnormal blood flow(low shear stress) as compared with those under normal blood flow conditions. 2) Acetylcholine caused endothlium-dependent relaxations in the control veins, while in the vein grafts,there was no evidence of endothelium-dependent relaxations to acetylcholine 3 days after implantation.3) Under abnormal blood flow(lowshear stress) conditionsendothelium-dependent relaxation of femoral artery and autovein graft caused by ADP or thrombin was selectively disturbed. 4) Serotonin(5HT) caused endothelium-dependent relaxation in control vein, while in autovein graft caused striking contraction. These results suggest that the decreased production of PGI_2 under an abnormal blood flow(low shear stress) condition and selective loss of endothelium-dependent relaxation of autovein graft under a cricumstance of arterial blood flow were important factors contributing late graft failure of autovein grafts.