Direct measurement of nitric oxide release from saphenous vein: abolishment by surgical preparation

Background. Surgical preparation (distension) of the saphenous vein (SV) is applied routinely during harvesting in coronary artery bypass grafting (CABG). However, mechanical distension may impair the endothelium, which plays an important role in long-term patency. The present study investigated the effect of surgical preparation of the SV on nitric oxide (NO) release from the endothelium by direct measurement of NO. Methods. Saphenous vein segments taken from CABG patients were cut open longitudinally and placed in an organ chamber. An NO-sensitive electrode and NO meter were used to directly measure NO release induced by acetylcholine (ACh) and bradykinin (BK) from the surgically prepared veins (PV) compared with the control (nondistended) veins. Results. The basal release of NO in the PV group was significantly lower than that in the control group (3.4 ± 1.4 nM, N = 9 versus 9.9 ± 2.8 nM, N = 13, p = 0.002). The maximum concentrations of NO release induced by ACh and BK in the PV group were also significantly lower than those in the control veins (for ACh 10−6 mol/L: 9.6 ± 3.1 nM, N = 8 versus 41.9 ± 11.2 nM, N = 12, p = 0.005; for BK 10−8 mol/L: 8.3 ± 3.7 nM, N = 7 versus 37.9 ± 6.1 nM, N = 9, p = 0.003). Further, the duration of NO release in the PV group was significantly shorter than that in control veins (1.5 ± 1.3 minutes, N = 8 versus 8.1 ± 1.9 minutes, N = 8, p < 0.001). Conclusions. Surgical preparation almost abolishes NO release by the SV and this may significantly contribute to the low long-term patency rate of the vein graft.