Role of endothelin B receptor in the pathogenesis of ischemic acute renal failure

This study evaluated the role of endothelin B (ETB) receptor-mediated action in the development and maintenance of ischemic acute renal failure (ARF), using the spotting-lethal (sl) rat that carries a naturally occurring deletion in the ETB receptor gene. Because homozygous (sl/sl) rats die shortly after birth due to congenital distal intestinal aganglionosis, genetic rescue of sl/sl rats from the developmental defect using a dopamine-beta-hydroxylase (DbetaH)-ETB transgene was performed to produce ETB-deficient adult rats. Rescued homozygous (DbetaH-ETB sl/sl) and wild-type (DbetaH-ETB +/+) rats were subjected to ischemic ARF by clamping the renal pedicle for 45 min followed by reperfusion. At 24 h after the reperfusion, renal glomerular dysfunction and histologic damage, such as proteinaceous casts in tubuli, were markedly and observed equally in homozygous and wild-type groups, and these renal injuries gradually recovered. However, when the ischemia/reperfusion-induced renal injury was examined 7 days after the reperfusion, the recovery in homozygous ARF rats was obviously delayed compared with the wild-type animals. Two of the eight homozygous ARF rats died within 3 days after the reperfusion. Increment of renal endothelin-1 content after the ischemia/reperfusion was more marked in homozygous than in wildtype rats. Thus, ETB receptor-mediated actions do not play an important role in the development of ischemic ARF but may be involved in the recovery process from ischemia/reperfusion-induced renal injury.