The maximum capacity for active sodium-potassium transport in the slow and fast skeletal muscle of obese (ob/ob) and lean mice

Abstract

Mature, genetically obese mice (C57BL/6J ob/ob) display obesity, hyperinsulinemia and resistance to insulin. These findings confirm the hypothesis that the obese mouse can be used as an animal model for the study of type II diabetes (8). Previously it has been shown, that particular fractions obtained from the hind limb muscles of obese mice contain fewer [3H]-ouabain binding sites than those prepared from lean Utter mates (6). In contrast, others have demonstrated that the number of [³H]-ouabain binding sites showed no significant difference in intact soleus and extensor digitorum longus muscles obtained from 9–20 week-old obese and lean mice (2). The state of resistance to the action of insulin, however, develops in muscles (e.g. soleus, diaphragm) only during the late phase of obesity (4). The aim of the present study was to compare the vanadate-facilitated binding of [³H]-ouabain and the maximum rate of ouabain-suppressible K⁺ uptake in samples of extensor digitorum longus muscle and soleus muscle from mature obese mice of C57BL/6J-ob/ob strain and their lean littermates.