Abstract
The purpose of this study was to characterize the effects of prior swim exercise on glucose uptake in isolated skeletal muscles of mice. Male and female mice (C57BL/6) performing 180 min of swimming had significantly decreased glycogen concentration compared to resting controls in soleus, extensor digitorum longus (EDL), and epitrochlearis muscles, regardless of gender. Glucose uptake by isolated muscles was measured using [3H]-2-deoxyglucose without insulin or with 180 pmol/l insulin (20, 75, or 200 min post-exercise and sedentary) or 12,000 pmol/l (20 or 200 min post-exercise and sedentary) in the soleus and EDL and without insulin or with 12,000 pmol/l insulin (20 or 200 min post-exercise and sedentary) in the epitrochlearis. Glucose uptake was higher (P ≤ 0.01) for female versus male mice at each insulin concentration in the soleus and EDL, but not the epitrochlearis. Although prolonged (180 min) swim exercise did not alter subsequent glucose uptake, a shorter duration exercise protocol (60 min) tested in male mice (20 min post-exercise) led to a 1.5-fold increase in insulin-independent glucose uptake in EDL muscles. However, insulin-stimulated (180 pmol/l) glucose uptake was not altered by 60 min exercise in EDL or soleus. In light of these results, swim exercise is not recommended to evaluate the exercise-induced improvement in insulin-stimulated glucose uptake of muscles of C57BL/6 mice.
