Satellite cells derived from streptozotocin-diabetic rats display altered fusion parameters in vitro

Myogenic satellite cells were isolated from nondiabetic and streptozotocin-diabetic rats and studied in vitro. Streptozotocin (STZ) administration produced both hyperglycemia and glucosuria in adult rats when compared to controls. (P less than 0.01), with 12.5% mortality in untreated animals. Insulin therapy diminished blood glucose levels to those found in nondiabetic animals. Only STZ-diabetic rats displayed symptoms of Type I diabetes, including polydipsia, polyuria, and hyperphagia. STZ-treated rats possessed less leg muscle mass and less subcutaneous, intermuscular, and intramuscular fat. Conversely, nondiabetic rats had a greater mean body weight (P less than 0.01) at the end of the experiment than did diabetic rats. Primary cultures of diabetic-derived satellite cells displayed decreased overall ability (P less than 0.01) to fuse to form multinucleated myotubes in vitro than controls. In addition, secondary cultures of diabetic-derived satellite cells achieved maximal fusion one day later than secondary cultures of control-derived cells. Collectively, these data provide preliminary evidence to suggest that untreated insulin-dependent diabetes results in altered fusion characteristics of myogenic satellite cells. Additional studies utilizing satellite cells from diabetic animals will provide valuable definition of the satellite cell involvement in skeletal muscle autophagy which is a symptom of type I diabetes.