T-type Ca2+ channels play an important role in many cellular processes such as hormone secretion, neurotransmitter release and cell differentiation. T-type channels are also known to participate in the pacemaker activities of heart and neurons including thalamic neurons.1 Three genes encoding T-type Ca2+ channels have been cloned and designated as CaV3.1 (α1G), CaV3.2 (α1H) and CaV3.3 (α1I).While CaV3.1 (α1G) and CaV3.2 (α1H) are widely expressed in various tissues, CaV3.3 (α1I) is primarily expressed in the central nervous system, where high expression was described in thalamic neurons. The Ca2+ current generated by the CaV3.3 channel displays much slower activation and inactivation compared to the currents produced by CaV3.1 and CaV3.2, suggesting it might play a different role in neuronal excitability.
