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 ([Ca2+]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 [Ca2+]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 Ca2+ transmembrane flow. In this way, VDAC participates
in the modulation of human sperm motility through mediating Ca2+ transmembrane transport
and exchange.