The effects of calcium (Ca2+) channel antagonists on the T-type Ca2+ channel current were investigated in Human Embryonic Kidney (HEK-293) cells heterologously expressing the a subunit of the human cardiac T-type Ca2+ channel. Ca2+ current were elicited by depolarization in 1.8 mM Ca2+ and recorded in the whole-cell configuration of the patch-clamp technique. The T-type Ca2+ current was inhibited by the following calcium channel antagonists: mibefradil (IC50=0.89μM), efonidipine (IC50=0.43μM) and nifedipine (IC50=1.91μM) . However, the agents differed in the use dependence of their effects. Mibefradil and efonidipine exhibit a strong use-dependent inhibition of the current that is due to selective interaction with the open state and the inactivated state of the channel, rather than with the resting state. Voltage dependence of inactivation and activation were modified in the presence of these agents: both curves were shifted in the hyperpolarized potentials by 5-10 mV by application of these Ca2+ channel antagonists at the concentration of IC50, respectively.