L-type and T-type calcium channel

L-type and T-type calcium channels are two distinct classes of voltage-gated calcium channels widely expressed in cardiac, vascular smooth muscle, and neural tissues. L-type calcium channels, primarily the Cav1.2 isoform, are high-voltage activated channels that mediate calcium influx in response to membrane depolarization, triggering smooth muscle contraction, heart muscle contractility, and hormone secretion. T-type calcium channels, including the Cav3.1, Cav3.2, and Cav3.3 isoforms, activate at lower voltages and inactivate rapidly, contributing to pacemaking activity, neuronal firing, and modulation of vascular tone. Both channel types play critical roles in excitation-contraction coupling, regulation of vascular resistance, heart rhythm, and cellular proliferation. Numerous calcium channel blockers target L-type channels for hypertension and cardiac disease, while T-type selective inhibitors like mibefradil (now withdrawn) have been explored for arrhythmias and neurological disorders. Channel dysfunction or dysregulation is implicated in cardiovascular, neurological, and proliferative diseases.

Other names

Voltage-gated calcium channel (Cav1 and Cav3 families)Cav1.2 (L-type)Cav3.1/Cav3.2/Cav3.3 (T-type)Voltage-dependent calcium channel

Inhibition of calcium influx during membrane depolarization to reduce muscle contraction, vascular tone, or pacemaker activity; Stabilization of cell membrane potential by reducing T-type channel opening