Insulin and insulin mutants stimulate glucose uptake in rat adipocytes

A simple method to determine the in vitro biological activity of insulin by measuring glucose uptake in the rat adipocytes is presented here. In the p resence of insulin, the glucose uptake is 5-6 rimes more than the basal con trol. And the uptake of D-[3-H-3] -glucose is linear as the logarithm of in sulin concentration from 0.2 mu g/L to 1.0 mu g/L. Glucose and 3-O-methyl-g lucose inhibit D-[3-H-3]-glucose uptake into adipocytes. By this method, th e in vitro biological activity of [B-2-Lys]-insulin and [B-3-Lys]-insulin w as measured to be 61.6% and 154% respectively, relative to that of insulin.