Effect of Fasting and Streptozotocin Diabetes on Insulin Binding and Action in the Isolated Mouse Soleus Muscle

Abstract

To investigate whether skeletal muscle is resistant to insulin in insulinopenic states, insulin binding and biological effects on glucose utilization were studied in isolated soleus muscles from 24- or 48-h-fasted mice and from streptozotocin-diabetic mice. Both 48-h fasting and diabetes led to an increase in insulin binding at insulin concentrations a) at low insulin concentrations insulin binding is increased and insulin effectiveness in stimulating glucose transport and metabolism is enhanced; (b) biological responses to maximally effective insulin concentrations are either unaltered or slightly increased; (c) basal rates of glucose transport and metabolism are essentially unaltered. These results indicate that in insulinopenic states soleus muscle is not insulin resistant in vitro but is hypersensitive to low concentrations of insulin, and normally responsive to maximally effective doses of the hormone.