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

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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.