Radioligand binding assay of insulin receptor in rabbit kidney during ischemic and reperfusion

AIM: To observe the change of insulin receptor in rabbit kidney with acute ischemic-reperfusion injury. METHODS: 15 Japanese white rabbits were allocated randomly into control group, ischemic-reperfusion group(IR group). IR group received clamping for 1 h followed by 2 h or 48 h of reperfusion. At 2 h or 48 h after reperfusion, glucose and insulin in serum were determined. Insulin receptor in renal tissue was analyzed by radioligand binging assay(BAD). RESULTS: The level of serum glucose increased after 2 h reperfusion in 2 groups, but in IR group the value increased much more higher than those in control groups(P＜0.05). Plasma insulin of IR group was significantly higher than that in control after 2 h reperfusion(P＜0.05). Scatchard analysis of data resulted in curvilinear profiles, indicating that there are two classes of receptors with different affinity or the presence of a single class of receptors with a negative cooperative hormone-receptor interaction. Data analyzed for a two-site model showed that the values of Bmax₁(high affinity site), Bmax₂(low affinity site) and Kd₁, Kd₂ were significantly lower than that of control (P＜0.05) after 2 h perfusion. 48 h after IR there was no difference of Bmax₁, Bmax₂, and Kd₁ between 2 groups,but Kd₂ of IR group was higher than that of control (P＜0.05). CONCLUSIONS: The results indicate that the effect of intrinsic insulin decreases in the progress of the renal ischemic-reperfusion. The resulting high serum glucose may aggravate renal injury in the progress of ischemic-reperfusion.