t or transverse tubules in skeletal muscle function to
T-tubule Transverse tubules (T-tubules) are extensions of the cell membrane that penetrate into the centre of skeletal and cardiac muscle cells.  With membranes that contain large concentrations of ion channels, transporters, and pumps, T-tubules permit rapid transmission of the action potential into the cell, and also play an important role in regulating cellular calcium concentration. Through these mechanisms, T-tubules allow heart muscle cells to contract more forcefully by synchronising calcium release throughout the cell.[1] T-tubule structure may be affected by disease, potentially contributing to heart failure and arrhythmias. Although these structures were first seen in 1897, research into T-tubule biology is ongoing.