Urinary nitrate excretion is a noninvasive indicator of acute cardiac allograft rejection and nitric oxide production in the rat

Cytokine induction of calcium-independent nitric oxide synthase is associated with production of large amounts of nitric oxide (NO). NO is a free radical that is rapidly degraded to nitrite and nitrate. Measurement of plasma and urinary nitrate is an indirect marker of NO production and previous studies have demonstrated that plasma nitrate rises with allograft rejection. The purpose of this study was to examine the temporal relationship between the rise in urinary nitrate excretion and the onset of graft rejection, and to determine the effect of conventional immunosuppression on nitrate excretion. The heterotopic model of cardiac transplantation in the rat was used, with Brown-Norway to Lewis allografts and Lewis to Lewis isograft controls