Glycocalyx is not required for show inward calcium current in isolated rat heart myocytes.

The importance of the slow inward calcium current (Isi) in the excitation-contration coupling process of cardiac muscle is well documented. The current can be attributed mainly to a calcium translocation from the extracellular space into the cell or a subsarcolemmal compartment of it. Isi has been suggested to have its source in and to be controlled by the surface coat of the sarcolemma (glycocalyx). The glycocalyx is destroyed in myocytes dissociated from adult heart tissue with solutions containing low calcium, collagenase and hyaluronidase (Fig. 1). By comparing the Isi data obtained in isolated myocytes with those reported for trabeculae or papillary muscles, we have now obtained evidence suggesting that the glycocalyx is not important in the genesis of Isi.