Nitrosyl hemoglobin detected by near-infrared spectroscopy in rat liver allografts

Near-infrared spectroscopy (NIRS) is a noninvasive biomeasurement system with rays in the near-infrared region that possess high permeability to biological tissues. NIRS was applied to liver allografts undergoing rejection in rats treated with deoxyspergualin (DSG) or tacrolimus (FK506). The nitrosyl hemoglobin (Hb) levels detected in the liver grafts increased 3 days and 5 days after grafting in both allogeneic and syngeneic transplantation. The levels on day 8 remained high in the allogeneic graft, but markedly decreased in the syngeneic graft. Although the serum levels of nitrite and nitrate were extremely low 8 days after grafting in allografted recipients treated with DSG or FK506, the nitrosyl-Hb level in DSG-treated graft was much higher than that in FK506-treated graft. There was no significant difference in survival time between DSG-treated and FK506-treated recipients. In conclusion, DSC and FK506 have a different effect on NO production in allografted liver with ongoing rejection, and circulating nitrite and /nitrate levels do not reflect the local levels of NO in the graft.