Background: The pH of semen is one of the important elements for maintaining spermatic normal functions. Variation of semen pH could lead to male infertility, but the mechanism of which is still unknown.
Methods: The healthy human spermatozoa cultured in sperm nutrition solution with pH 5.2, 6.2, 7.2, 8.2, 9.2 and 10.2 respectively were analyzed for sperm motility, vitality, hypoosmotic swelling rate, Na/K-ATPase activity and the intracellular Caconcentration.
Results: The results showed that sperm motility, vitality, hypoosmotic swelling rate were all on the peak in pH 7.2 sperm nutrition solution, and decreased in different degree in pH 5.2, 6.2, 8.2, 9.2 and 10.2. Furthermore, the hypoosmotic swelling rate had a positive correlation with the sperm motility and viability. Sperm penetration meter test was displayed that in compared with pH 7.2, the sperm ascending altitude in sperm nutrition solution with pH 5.2, 6.2, 8.2, 9.2 and 10.2 were significantly declined. In addition, sperm Na/K-ATPase activity in sperm nutrition solution with different pHs was detected and the enzyme activity were significantly lower in pH 5.2, 6.2, 8.2, 9.2 and 10.2 medium compared to pH 7.2. Using flow cytometry and laser confocal scanning microscope to contrast the intracellular Ca concentration of sperm cultured in pH 5.2, 6.2, 7.2, 8.2, 9.2 and 10.2 sperm capacitation solution. Taking pH 7.2 group as a control, the mean fluorescence intensity of sperm in pH 5.2, 6.2 and 10.2 medium were decreased significantly, while pH 8.2 and 9.2 group had no differences with control.
Conclusions: All the results suggested that hydrogen-ion concentration outside spermatozoa could affect sperm motility and capacitation by influencing sperm Na/K-ATPase activity and spermoplasm Ca concentration revealing one of the mechanisms of male infertility.
