Biophysics and physiology of cardiac calcium channels

Two types of calcium channels are present in heart cells; the two types, L and T, can be clearly distinguished on the basis of their biophysical and pharmacological properties. The physiological role of L-type Ca²⁺ channels is clear and includes mediation of processes that are vital to the function of normal cardiac cells, such as electrical conduction and excitation- contraction coupling. The physiological role of T-channels is not known, although potential involvement in pacemaker activity can be hypothesized on the basis of their biophysical properties. The testing of these predictions is the subject of intense research interest at present.