Hyaluronic acid increases motility/intracellular Ca2+ concentration in human sperm in vitro

This study investigated the mechanisms of the stimulatory effect of hyaluronic acid on motility in human sperm in vitro. A method, involving the measurement of forward progression through an agarose gel, was used to measure sperm motility quantitatively. Changes in intracellular Ca2+ concentrations in sperm were detected using the fluorescent dye Fluo-3. The effects of hyaluronic acid (6.5, 65, 650 ng/mL) and nifedipine (32 nM) on sperm motility were investigated. The effects of hyaluronic acid, nifedipine (32 nM), A23187 (32 muM), and a monoclonal antibody to human CD44 (1 mug/mL) on changes in intracellular CA(2+) concentrations were investigated. Hyaluronic acid significantly (p < .008) stimulated sperm motility and this was partially inhibited by nifedipine. A23187 significantly (p < .005) increased intracellular CA(2+) concentrations. Hyaluronic acid significantly (p < .04) increased intracellular Ca2+ concentrations and this was inhibited by nifedipine and a monoclonal antibody to human CD44. Hyaluronic acid stimulated human sperm motility by increasing intracellular Ca2+ concentration, partially via an influx of extracellular Ca2+.