Aim
To determine the effect of chromium chloride (CrCl3 ) on healthy skeletal muscle glucose uptake in the absence and presence of submaximal insulin using the rat hindlimb perfusion technique.
Conclusion
Exposure of healthy skeletal muscle to chromium may increase skeletal muscle insulin-stimulated GLUT4 translocation and glucose uptake. However, these effects do not appear to result from enhanced insulin signalling proximal to AS160.
Methods
Sprague-Dawley rats were randomly assigned to an experimental group: basal (Bas), chromium chloride (Cr), submaximal insulin (sIns) or chromium chloride plus submaximal insulin (Cr-sIns).
Results
Insulin significantly increased [H(3)]-2 deoxyglucose (2-DG) uptake in the gastrocnemius muscles. Additionally, Cr-sIns displayed greater rates of 2-DG uptake than sIns (Cr-sIns 6.86 ± 0.74 μmol g h(-1) vs. sIns 4.83 ± 0.42 μmol g h(-1)). There was no difference between Cr and Bas treatment groups. It has been speculated that chromium works to increase glucose uptake by increasing insulin signalling. We found that Akt and AS160 phosphorylation was increased in the sINS treatment group, while chromium treatment had no additional effect on Akt or AS160 phosphorylation in the absence or presence of insulin. Cr-sIns significantly increased plasma membrane GLUT4 concentration above that of sIns (Cr-sIns 72.22 ± 12.7%, sIns 53.4 ± 6.1%), but in the absence of insulin, chromium had no effect.