Résumé
Voltage gated calcium channels are involved in a large variety of cellular functions such as excitation contraction coupling, firing and pacemaking activity, neurotransmitter release, hormone secretion and gene activation. Cloning of complementary cDNA encoding for calcium channel subunits and studies of the recombinant current properties have allowed analysis of the molecular basis of calcium channel diversity. Recently, three pore-forming subunits (alpha (1G), alpha (1H,) alpha (1I)) of T-type calcium channels have been cloned and expressed in mammalian cells. A comparison between their functional properties and those of native T-type current in various cells including cardiac myocytes provides new insights in the nature and physiological role of T-type calcium channels.