Effects of Copper on T-Type Ca 2+ Channels in Mouse Spermatogenic Cells

Low voltage-activated, rapidly inactivating T-type Ca 2+ channels are found in a variety of cells, where they regulate electrical activity and Ca 2+ entry. In whole-cell patch-clamp recordings from mouse spermatogenic cells, trace element copper (Cu 2+ ) inhibited T-type Ca 2+ current ( I T-Ca ) with IC 50 of 12.06 μM. Inhibition of I T-Ca by Cu 2+ was concentration-dependent and mildly voltage-dependent. When voltage stepped to −20 m V , Cu 2+ (10 μM) inhibited I T-Ca by 49.6 ± 4.1%. Inhibition of I T-Ca by Cu 2+ was accompanied by a shift of −2.23 m V in the voltage dependence of steady-state inactivation. Cu 2+ upshifted the current–voltage ( I - V ) curve. To know the change of the gating kinetics of T-type Ca 2+ channels, we analyzed the effect of Cu 2+ on activation, inactivation, deactivation and reactivation of T-type Ca 2+ channels. Since T-type Ca 2+ channels are a key component in capacitation and the acrosome reaction, our data suggest that Cu 2+ can affect male reproductive function through T-type Ca 2+ channels as a preconception contraceptive material.