CAV3 mediates IMGU and NIMGU in skeletal muscle and cardiac myocytes.

Objective: To observe whether CAV3 is involved in the physiological process of IMGU and NIMGU. Downregulation of caveolin-3 (CAV3) protein expression by small interference RNAs (iRNA) has been studied. Insulin-mediated glucose uptake (IMGU) is critical in skeletal muscle and cardiac myocytes, but non - insulin -mediated glucose uptake (NIMGU) should not be neglected. Methods: CAV3 siRNAs were designed and transfected in C2C12 cells and H9c2 cells in skeletal muscle and cardiac muscle, respectively, and C2C12 and H9c2 cells were cultured in DMEM medium with and without insulin, respectively. Glucose transporter 4 (GLUT4) protein expression was detected by Western blot, and the glucose uptake rate of cells was measured by biochemical kit. Results: Transfection with CAV3 siRNA successfully down- regulated CAV3 protein expression in C2C12 and H9c2 cells. In the absence of insulin stimulation, GLUT4 expression was decreased (P<0.01) and glucose uptake was reduced (P<0.05) after 48 h of transfection in C2C12 cells, and GLUT4 expression was decreased (P<0.05) and glucose uptake was reduced (P<0.01) after 48 h of transfection in H9c2 cells. In the presence of insulin stimulation, GLUT4 expression was decreased (P<0.01) and glucose uptake was reduced (P<0.01) after 48 hours of transfection in C2C12 cells, and the down-regulation of GLUT4 was not statistically significant and glucose uptake was reduced (P<0.01) after 48 hours of transfection in H9c2 cells. Conclusion: Two different states, IMGU and NIMGU, exist in C2C12 cells and H9c2 cells. Both in the quiet state stimulated by insulin as well as in the absence of insulin stimulation, the cellular uptake of glucose is affected by GLUT4 changes regulated by CAV3. [ABSTRACT FROM AUTHOR]