Chapter 16 – Pharmacology of L-Type and T-Type Calcium Channels in the Heart

Calcium influx during the cardiac action potential (AP) is an essential process, because it triggers the release of calcium ion (Ca 2+ ) from the sarcoplasmic reticulum (SR) and thereby elevates cytoplasmic Ca 2+ to initiate contraction. Two types of voltage-dependent calcium channels, L- and T-type calcium channels, have been found in the heart. The L (long openings)-type Ca 2+ channel (LTCC) is the predominant Ca 2+ channel in heart cells and will be the principle focus of this chapter. Much less is known about the functional significance of the T (tiny conductance)-type Ca 2+ channel (TTCC).