Increased expression of low voltage-activated, T-type Ca2+ channels has been correlated with a variety of cellular events including cell proliferation and cell cycle kinetics. The recent cloning of three genes encoding T-type α1 subunits, α1G, α1H and α1I, now allows direct assessment of their involvement in mediating cellular proliferation. By overexpressing the human α1G and α1H subunits in human embryonic kidney (HEK-293) cells, we describe here that, although T-type channels mediate increases in intracellular Ca2+ concentrations, there is no significant change in bromodeoxyuridine incorporation and flow cytometric analysis. These results demonstrate that expressions of T-type Ca2+ channels are not sufficient to modulate cellular proliferation of HEK-293 cells.
