Effect of CatSper and Hv1 Channel Inhibition on Progesterone Stimulated Human Sperm

Background: Intracellular calcium and proton concentrations are important factors for activating human sperm. Calcium ion (Ca2+) enters sperm through voltagedependent calcium channel of sperm (CatSper). Proton was extruded from sperm through voltage-gated proton channel (Hv1). In the present study, the selective inhibitors of the CatSper and Hv1 channels, NNC 55-0396 (NNC) and zinc ion, respectively, were used to investigate functions of these channels. Methods: Normal semen samples (n=24) were washed and diluted to 20×106 sperm/ ml. The diluted sample was divided into 8 groups, containing Ham’s F-10 (the control group), 2 μM NNC, 1 mM ZnCl2 and NNC+Zn. The other 4 groups were the same as above, except that they contained 1 μM progesterone. The computer assisted analysis was done by VT-Sperm 3.1 to determine the percentage of motile sperm and sperm velocity. Acrosomal status was monitored by FITC-PSA and viability assessed by Eosin–Y staining. Statistical comparisons were made using ANOVA followed by Tukey post hoc test. The p<0.05 was considered significant. Results: The percentage of viable and motile sperm, curvilinear velocity and other parameters of motility was reduced in all groups containing NNC, zinc and NNC+ zinc. Progesterone–induced acrosome reaction was abolished by each of these inhibitors. The combination effect of NNC plus zinc on motility and progesterone–induced acrosome reaction was not stronger than NNC by itself. Conclusion: CatSper and Hv1 channels play a critical role in human sperm function and viability. It seems that a functional relationship exists between CatSper and Hv1 channels.