Exercise training increases glucose transporter protein GLUT-4 in skeletal muscle of obese Zucker (fa/fa) rats.

The present study examined the level of GLUT-4 glucose transporter protein in gastrocnemius muscles of 36 week old genetically obese Zucker (fa/fa) rats and their lean (Fa/-) littermates, and in obese Zucker rats following 18 or 30 weeks of treadmill exercise training. Despite skeletal muscle insulin resistance, the level of GLUT-4 glucose transporter protein was similar in lean and obese Zucker rats. In contrast, exercise training increased GLUT-4 protein levels by 1.7 and 2.3 fold above sedentary obese rats. These findings suggest endurance training stimulates expression of skeletal muscle GLUT-4 protein which may be responsible for the previously observed increase in insulin sensitivity with training.