Effects of the prostanoid receptor antagonist, di-4-phloretin phosphate, upon human sperm motility

The inhibitory effects of the prostanoid receptor antagonist, di-4-phloretin phosphate (DPP), upon washed human sperm motility were determined in vitro (up to 60 min of incubation). Concentrations tested were: 0.001, 0.01, 0.1, 0.25, 0.5, 2.5, 5.0 and 10.0 mM. All concentrations of DPP investigated caused cessation of sperm movement (percentage motility and average forward velocity) and the antimotility effect was essentially irreversible. The concentrations producing 50% inhibition were: percentage motility--1.31 +/- 0.56 mM (mean +/- SEM) and average forward velocity--1.95 +/- 0.68 mM. The mode of antimotility action appears to be multi-faceted. At high (10 mM) and intermediate (2.5 mM) concentrations, changes in fluidity of sperm plasmalemma (hypoosmotic swelling test) and loss of viability (nigrosin-eosin stain technique) constitute the primary means by which motility was disrupted. In contrast, these two parameters of motility remained unaltered at a lower concentration (0.25 mM) of DPP, and the mechanism precipitating the antimotility effect may involve mobilization of stored calcium ions and modulation of cyclic AMP levels.