Ischemic renal damage rats were obtained by cliping the kidney both artery, we used in situ hybridization in examing the expression of ET A-R mRNA in the renal tissue, Compared with the normal group, ET A-Rm RNA expression was significantly higher in the ischemic renal mesangial cell, P<0.05. These finding suggests that the ET may effect on the mechanisme of the renal damage of pathology.