Enhancement of nitric oxide production after arterial reconstruction in patients with arteriosclerosis obliterans

Purpose: Nitric oxide (NO) not only relaxes vascular smooth muscles, but it also reduces platelet adhesion and is itself a potent antiaggregatory substance. Experimental studies have shown that the release of NO is modulated by the blood flow. However, little clinical information is available about the effects of hemodynamic changes after arterial reconstruction on NO production. We therefore examined whether the plasma levels of nitrite (NO₂^-) and nitrate (NO₃^-) ions increased after arterial reconstruction in patients with arteriosclerosis obliterans (ASO). Methods: Blood samples were obtained from the femoral artery in seven patients who underwent arterial reconstruction and seven healthy individuals (control). NO₂^- and NO₃^- levels were measured using high-performance liquid chromatography before the operation and 1 hour and 14 days after the operation. In addition, the mean femoral artery blood flow and ankle-brachial pressure index (ABI) were also measured using a duplex and Doppler velocimeter both before and after the operations. Results: In the control subjects, the mean plasma NO₂^-, NO₂^-, and NO(X) (NO₂^- plus NO₃^-) levels in the femoral artery were 0.57 ± 0.15 μmol/L, 45.6 ± 10.8 μmol/L, and 46.0 ± 10.9 μmol/L, respectively. Before the operation in the patients with ASO, the mean plasma NO₃^- (23.8 ± 2.2 μmol/L) and NO(X) levels (24.0 ± 2.3 μml/L) were significantly lower than those in the control subjects, whereas the plasma NO₂^- levels (0.27 ± 0.04 μmol/L) were comparable between the two groups. At 14 days after operation, the mean plasma NO₃^- and NO(X) levels in the femoral artery were significantly increased to 42.8 ± 5.6 μmol/L and 43.4 ± 5.6 μmol/L compared with those before the operation, whereas the mean plasma NO₂^- levels (0.50 ± 0.05 μmol/L) changed significantly. The mean ABI and the mean flow rate before the operation were 0.32 ± 0.07 and 344 ± 145 ml/min, respectively. Both the ABI and the mean flow rate significantly increased to 1.04 ± 0.06 and 627 ± 141 ml/min after the operation. Conclusions: In patients who have ASO, the mean plasma level of NO is significantly lower than that of healthy individuals. In patients with ASO, the mean blood flow increased significantly after arterial reconstruction. This hemodynamic improvement may thus enhance NO production and may also help to maintain the patency of the bypass graft or native artery.