[Insulin and proinsulin degradation normally and in experimental diabetes]

The authors studied insulin and proinsulin degradation with homogenates of various rat tissues under normal conditions and in alloxan diabetes. The radioimmunological method was used for insulin determination by the decline of immunoreactive insulin and proinsulin from the reaction medium. Homogenates of various normal rat tissues are distributed by their capacity to destroy insulin and proinsulin in the order of decline as follows: the liver, kidneys, muscles, and the epididymal fat. In insulin equimolar quantities proinsulin was destroyed much less than insulin under the same experimental conditions. Alloxan diabetes led to reduction of the capacity of all the tissues homogenates to destroy both insulin and proinsulin. Reduction of degradation was the most pronounced when the muscle and adipose tissue homogenates were used.