GJA1 and diabetes mellitus: Accordingly, the sarcolemma permeabilization observed in skeletal myofibers can be reduced by blocking Cx HCs or P2X7Rs. The importance of HCs was clearly demonstrated by evaluating myofibers from diabetic mice deficient in Cx43 and Cx45 expression or by blocking all these non-selective membrane channels with boldine—two conditions that prevented muscle atrophy induced by diabetes.