Effects of Insulin from Normal and Diabetic Human Pancreas on RNA Labeling in Fibroblast Cultures

The nutrient medium of a series of cultures inoculated simultaneously with mouse fibroblasts of the 3T6 strain was replaced by fresh medium containing Uridine-2-C-14 and 5,000 μunits of insulin from four normal and two diabetic pancreases. After a twelve-hour incubation period the cellular monolayer was subdivided by conventional chemical methods and the specific activity of the RNA fraction estimated. A consistent difference was observed between RNA specific activity of the cellular monolayers treated with diabetic pancreatic insulin and normal pancreatic insulin. These data constitute a further argument strengthening the case for an “abnormal insulin in diabetes mellitus.”