Multi-faceted functions for the low-voltage-activated T-type calcium channels

Intracellular Ca2+ concentration controls a number of physiological functio ns some of which are initiated at quite negative membrane potentials (- 80 mV to - 50 mV). Such is the case for the oscillations recorded in thalamic neurons, but also in non-excitable cells, for spermatozoid capacitation, te rminal differentiation of myoblasts or aldosterone secretion. T-Type calciu m channels are major contributors to this Ca2+ signaling. They can generate in this range of potential either a large but transient Ca2+ entry or a sm all but sustained Ca2+ current, depending on the recent history of the memb rane potential. The cloning in 1998-99 of three T channels by the group of E. Perez-Reyes gives now access to new tools to delineate their exact contr ibution. The present review focuses on recent progress in our understanding of T channel functions.