Prolongation and improvement of prostasome promotive effect on sperm forward motility

Prostasomes isolated from human seminal plasma stimulated the forward motility of buffer-washed, and therewith immobilised, normal human spermatozoa in a dose- and time-related fashion. Albumin exhibited a similar capacity for stimulation. Combining prostasomes with 5 mmol/l of any of the hexoses fructose, glucose or mannose (but not galactose) resulted in a prolongation and improvement of the effect by prostasomes (or albumin) for the first 150 min. Hence, a dose-response effect at 60 and 120 min was obtained by prostasomes on sperm forward motility provided 5 mmol/l of fructose was present--otherwise not. Many substances besides the hexoses were examined for possible positive effects on sperm forward motility in concert with prostasomes with no additional effect. Enrichment of optimum concentrations of prostasomes and glucose with 2 mmol/l of adenine stimulated further the velocity parameters of the spermatozoa over time. The effect of adenosine was less evident under these conditions. Experiments carried out with prostasomes in the presence of divalent cations or chelators suggested that magnesium ions are essential for sperm forward motility. There appeared to be a safety margin concerning calcium ions, and zinc ions did not seem to be primarily involved in sperm forward motility in the presence of prostasomes.