T-type calcium channels: from cloning to physiology

The cloning of three genes coding for T-type calcium channels has been an i mportant step towards identifying the links between voltage-dependent calci um influx and cellular excitability. The classical electrophysiological mea surement of native low-voltage-activated, transient calcium currents (T-typ e currents) has been further refined by the ability to study individually i dentified classes of molecules of this channel family, and the possibility of developing therapeutic agents targetting T-type calcium channels. This r eview describes both the identification and the molecular and functional pr operties of this novel channel family. T-type calcium channels are thought to play a role in several physiological and pathophysiological processes, s uch as neuronal and cardiac pacemaker activities, hormone secretion, epilep sy, cardiac hypertrophy. It will be now possible to investigate the precise contribution of these channels in various cellular essays as well as in an imal models.