Asthenozoospermia, which is characterized by reduced motility, is one of the etiologies of male infertility. Its biochemical and functional consequences include altered ATPase activity. This study investigated the activities of Na+, K+-ATPase and Ca2+-ATPase and the expression of Na+, K+-ATPase α4 and PMCA4 isoforms in human sperm of asthenozoospermic infertile men. Nineteen samples from asthenozoospermic infertile couples were examined in this study. Computerized-assisted semen analysis (CASA) was performed, and the enzyme activity was measured based on the ability of ATPase to release organic phosphate from ATP as a substrate. The Na+, K+-ATPase α4 and PMCA4 isoform expression levels were measured by western immunoblotting, whereas the protein distribution was examined by immunocytochemistry. This showed that the Na+, K+-ATPase activity and the Na+, K+-ATPase α4 isoform expression were lower in the asthenozoospermia group than in the normozoospermia group (8.688±1.161 versus 13.851±1.884 µmol Pi/mg protein/h, respectively; p>0.05). In contrast, the Ca2+-ATPase activity was significantly higher in the asthenozoospermia group than in the normozoospermia group (11.154±1.186 versus 2.725±0.545 µmol Pi/mg protein/h, respectively; p<0.05). In comparison, PMCA4 expression in the asthenozoospermia group was lower than in the normozoospermia group (p>0.05). The altered ATPase activity and isoform expression in asthenozoospermia may impair sperm structure and function.
- K-ATPase α4