The role of endothelin in the pathophysiology of renal impairment during acute liver rejection.

We assessed the role of endothelin in the development of renal dysfunction during acute rejection by examining the effect of a selective endothelin A (ETA) receptor antagonist BQ-123 in rats with acute liver rejection. Serum endothelin levels and endogenous creatinine clearance (Ccr) were monitored on days 1, 3, 5, 7, and 9 postoperatively. As indicators of renal hemodynamics, the estimated hemoglobin concentration of renal tissue (IHb) and the oxygen saturation of hemoglobin in renal blood (ISO2) were determined by reflectance spectrophotometry. In addition, the clearance of inulin and P-aminohippurate were determined, and the renal tissue blood flow was estimated by laser-Doppler flowmetry (LDF). As a model of allograft rejection, Lewis rats were transplanted orthotopically with DA rat livers. The serum endothelin level of allografted rejectors was significantly (P < 0.05) higher than that of isografted controls (Lewis rats with Lewis livers) on postoperative day 5, and it increased to a maximum of 5.38 +/- 0.95 pg/ml on day 9 (versus 1.23 +/- 0.18 pg/ml preoperatively). The values of Ccr, IHb, and ISO2 were all significantly (P < 0.05) lower in allografted rejectors than in isografted controls on day 5, and subsequently declined to a minimum on day 9 (P < 0.01). Treatment of allografted rejectors with BQ-123 markedly improved the renal parameters to levels similar to those in the isografted controls. These results strongly suggest that endogenous endothelin may play an important role in the development of renal impairment during acute liver rejection by reducing renal blood flow through binding with ETA receptor.