The influence of streptozotocin diabetes and metformin on erythrocyte volume and on the membrane potential and the contractile characteristics of the extensor digitorum longus and soleus muscles in rats.
The effects of streptozotocin (STZ) diabetes and the antihyperglycaemic agent metformin on the contractile characteristics of the limb skeletal muscles and on erythrocyte volume were examined in rats. After 8 weeks of diabetes, the tetanic tension of the extensor digitorum longus (EDL) muscle decreased and the half-relaxation time of the soleus muscle increased. Endurance decreased in both muscles. Metformin treatment of the diabetic rats did not prevent the development of these contractile changes. Diabetes induced depolarisation in the EDL and soleus muscles. Following exposure to insulin, both muscles repolarized. Metformin treatment of control rats induced depolarisation in the EDL and soleus muscles, but in the depolarised EDL and soleus muscles of the diabetic rats metformin treatment caused no further depolarisation. The muscles of metformin-treated control and diabetic rats hyperpolarized in the presence of insulin. Diabetes caused an increase in the volume of the blood erythrocytes. This was prevented by metformin treatment.
McGuire
M
M
Department of Physiology, Royal College of Surgeons in Ireland, 123 St Stephens Green, Dublin 2, Ireland.
MacDermott
M
M
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy / Q000503:physiopathology*; D004911:Erythrocyte Volume / Q000187:drug effects*; D006403:Hematologic Tests; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008687:Metformin / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects; D018763:Muscle Fatigue / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000503:physiopathology; D051381:Rats; D017208:Rats, Wistar
D007004:Hypoglycemic Agents; D007328:Insulin; D008687:Metformin