Insulin and insulin mutants stimulate glucose uptake in rat adipocytes

A simple method to determine thein vitro biological activity of insulin by measuring glucose uptake in the rat adipocytes is presented here. In the presence of insulin, the glucose uptake is 5–6 times more than the basal control. And the uptake of D-3-3H]-glucose is linear as the logarithm of insulin concentration from 0.2 g/L to 1.0 g/L. Glucose and 3-O-methyl-glucose inhibit D-3-3H]-glucose uptake into adipocytes. By this method, thein vitro biological activity of B2-Lys]-insulin and B3-Lys]-insulin was measured to be 61.6% and 154% respectively, relative to that of insulin. Project supported by the Chinese 863 Foundation.