Insulin stimulation of growth in diabetic rats. Synthesis and degradation of ribosomes and total tissue protein in skeletal muscle and heart.

Skeletal muscle and heart of diabetic rats show a substantial decline in the rate of protein synthesis associated with decreases in both the number and activity of tissue ribosomes. We have examined the reversal of these changes during the first 3 days of resumption of insulin therapy to rats that had been diabetic for 4 days. Rates of ribosome degradation, which had been elevated in both muscle and heart of the diabetic animals, were suppressed virtually to zero after 1 day of insulin treatment. Synthesis of ribosomes was stimulated, but this change occurred more gradually. Similar, but less dramatic, changes occurred in the rates of synthesis and degradation of total protein in these tissues.