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

根据我们以前的报告，旁路移植术的结果与手术时电磁确定的血流波形模式密切相关，确定通畅的一个重要因素是一个心动周期内的剪应力变化，我们研究了异常血流动力学的影响（低剪切应力）对犬股动脉内皮细胞和平滑肌细胞功能的影响后肢径流模型。结果表明：（1）与正常血流条件下相比，在血流异常（低切应力）条件下，股动脉和自体移植静脉内皮细胞的PGI_2生成率显著降低。2)乙酰胆碱可引起对照组静脉内皮依赖性舒张，而移植静脉在阻断后3天，乙酰胆碱无内皮依赖性舒张作用。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移植静脉内皮依赖性舒张被选择性干扰。4)5-羟色胺（5-HT）引起对照静脉内皮依赖性舒张，而自体移植静脉引起显著收缩。结果提示，在血流异常（低切应力）条件下，PGI_2生成减少，在动脉血流阻断条件下，移植静脉内皮依赖性舒张功能选择性丧失，是移植静脉晚期衰竭的重要因素。

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.