Co-incubation of human spermatozoa with anti-VDAC antibody reduced sperm motility.

BACKGROUND Voltage-dependent anion channel (VDAC), a channel protein, exists in the outer mitochondrial membrane of somatic cells and is involved in multiple physiological and pathophysiological processes. Up until now, little has been known about VDAC in male germ cells. In the present study, the relationship between VDAC and human sperm motility was explored. METHODS Highly motile human spermatozoa were incubated in vitro with anti-VDAC antibody. Total sperm motility, straight line velocity (VSL), curvilinear velocity (VCL), and average path velocity (VAP) were recorded. Intracellular free calcium concentration ([Ca(2+)]i), pH value (pHi), and ATP content were determined. RESULTS Co-incubation with anti-VDAC antibody reduced VSL, VCL, and VAP of spermatozoa. Co-incubation further reduced [Ca(2+)]i. Anti-VDAC antibody did not significantly alter total sperm motility, pHi and intracellular ATP content. CONCLUSION The data suggest that co-incubation with anti-VDAC antibody reduces sperm motility through inhibition of Ca(2+) transmembrane flow. In this way, VDAC participates in the modulation of human sperm motility through mediating Ca(2+) transmembrane transport and exchange.