Glycogen repletion in different skeletal muscles from diabetic rats

It was hypothesized that chronically untreated streptozotocin-diabetic rats may compensate for the detrimental effect of insulin deficiency on glycogen restoration following muscular work. Glycogen concentration ([GLY]) was reduced by in situ stimulation of the sciatic nerve of anesthetized normal (N) and diabetic (D) Sprague-Dawley albino rats. Glycogen repletion occurred most rapidly within 30 min after stimulation. By 2 h all N muscles returned to basal [GLY]. D muscles repleted glycogen at a rate 45-75% of normal and not all of the D muscle returned to basal [GLY] by 8 h poststimulation. Neither the partial reduction in diabetic hyperglycemia by using phlorizin nor the acute further lowering of diabetic hypoinsulinemia by using insulin antibody affected glycogen restoration in D muscles. Acute insulin replenishment resulted in restoration of normal [GLY] in D muscles within 2 h poststimulation. These findings are not consistent with the proposed hypothesis and indicate insulin is necessary to have normal rates of glycogen restoration following muscular activity.