Insulin Binding and Degradation by Muscles from Streptozotocin-diabetic Rats

Insulin degradation by muscle was examined in normal, streptozotocin-induced diabetic rats, and diabetic rats treated with insulin. Insulin degradation by the 100,000 × g supernatant fractions was identical in all three groups, but insulin metabolism by the intact epitrochlaris muscle was significantly increased in diabetic animals. Insulin treatment of the diabetic animals partially restored the activity toward normal. Specific binding of ¹²⁵I-insulin to the intact muscles was also increased in the diabetic animals. Streptozotocin diabetes, therefore, increased the binding and degradation of insulin by intact muscle but did not alter the insulin degradation by the total soluble intracellular degradative activity.