Effects of nifedipine on insulin receptors in rat hepatocytic membrane

Objective: To investigate the effects of calcium antagonist nifedipine（NF）on insulin receptors in rat hepatocytic membrane and explore the effects of NF on biological action of insulin.Methods: Exp 1: The rat livers were perfused with different concentrations of NF（0.5,1 0,and 1 0.0μmol/L）,and the preparation of hepatocytic membrane was produced for measuring the binding capacity of insulin receptors by radioimmunoassay Exp 2: The hepatocytic membrane samples from non NF treated were reacted with different concentrations of NF for measuring the binding capacity of insulin receptor.Results: Exp 1 showed that the maximal binding capacity （Bmax）,affinity constant （K 1） and binding sites（Q 1） of higher affinity receptor were not influenced by 3 scale concentrations of NF,whereas,the affinity constant（K 2）of lower affinity receptor was elevated in manner of NF dose dependence,and the binding sites（Q 2）of lower affinity receptor were reduced Exp 2 showed that the Bmax,Q 1,Q 2 and K 2 were decreased by 3 scale concentrations of NF in a manner of dose dependence,and the higher concentrations of NF lowered K 1 either.Conclusion: NF influenced the binding capacity of insulin receptor in the hepatocytic membrane at some extent by means of the direct reaction.