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

This study investigated the mechanisms of the stimulatory effect of hyaluro nic acid on motility in human sperm in vitro. A method, involving the measu rement of forward progression through an agarose gel, was used to measure s perm motility quantitatively. Changes in intracellular Ca2+ concentrations in sperm were detected using the fluorescent dye Fluo-3. The effects of hya luronic acid (6.5, 65, 650 ng/mL) and nifedipine (32 nM) on sperm motility were investigated. The effects of hyaluronic acid, nifedipine (32 nM), A231 87 (32 muM), and a monoclonal antibody to human CD44 (1 mug/mL) on changes in intracellular CA(2+) concentrations were investigated. Hyaluronic acid s ignificantly (p < .008) stimulated sperm motility and this was partially in hibited by nifedipine. A23187 significantly (p < .005) increased intracellu lar CA(2+) concentrations. Hyaluronic acid significantly (p < .04) increase d intracellular Ca2+ concentrations and this was inhibited by nifedipine an d a monoclonal antibody to human CD44. Hyaluronic acid stimulated human spe rm motility by increasing intracellular Ca2+ concentration, partially via a n influx of extracellular Ca2+.