Impaired enhancement of insulin action in cultured skeletal muscle cells from insulin resistant type 2 diabetic patients in response to contraction using electrical pulse stimulation.

AIMS

Skeletal muscle insulin resistance is a characteristic feature of type 2 diabetes. The aim of this study was to examine the effect of contraction on insulin action using electrical pulse stimulation (EPS) in cultured skeletal muscle cells from insulin resistant type 2 diabetic patients.

METHODS

Skeletal muscle cell cultures were established from 6 insulin resistant type 2 diabetic subjects and age and BMI matched non-diabetic control subjects. Day 7 differentiated myotubes were treated with or without EPS for 16 h, after which glucose uptake and AS160 phosphorylation were measured in the presence or absence of insulin.

RESULTS

In control myotubes, EPS resulted in increased phosphorylation of AMPKThr (vs no EPS; p < 0.01), and this was associated with increased glucose uptake (p < 0.05). Insulin in the absence of EPS increased glucose uptake and AS160Thr phosphorylation, and both effects were significantly enhanced by prior EPS. In the absence of EPS, AMPK activation was significantly increased (p < 0.01) in the diabetic vs control myotubes. Despite a comparable degree of AMPK activation following EPS, the action of insulin on glucose uptake (p < 0.05) and AS160Thr phosphorylation (p < 0.001) was decreased in the diabetic vs control myotubes.

CONCLUSION

EPS mediated AMPK activation enhances the effect of insulin on glucose uptake and AS160Thr phosphorylation in control myotubes replicating key metabolic benefits of exercise on insulin action in man. Conversely, insulin mediated glucose uptake and AS160Thr phosphorylation remain significantly decreased in diabetic vs control myotubes despite a comparable degree of AMPK activation following EPS.