Inhibition of T-type Ca(2+) currents in mouse spermatogenic cells by gossypol, an antifertility compound

Gossypol, a male antifertility compound isolated from cotton, has been proved to inhibit capacitation and the acrosome reaction in human and mammalian sperm. Here, by using whole-cell recording, we observed the effects of gossypol on Ca(2+) and Cl(-) currents in mouse spermatogenic cells obtained by mechanical dissociation. The results showed that gossypol concentration-dependently and irreversibly inhibited T-type Ca(2+) currents in the cells. When the concentration of gossypol was > or =5 microM, the currents were blocked completely. The time to current block was progressively shortened as the gossypol concentration was increased from 5 to 80 microM. Moreover, the drug increased the time constant of inactivation in a concentration-dependent manner, while it did not affect the activation of the current. The inhibitory effect on the T-type Ca(2+) current did not correlate with signaling mediated by G proteins and tyrosine phosphorylation. No obvious effect of gossypol on Cl(-) currents was observed. These data suggest that the gossypol-induced inhibition of T-type Ca(2+) currents could be responsible for the antifertility activity of the compound, indicating a possibility to use gossypol as a local contraceptive drug.