Effect of cAMP, Mn2+, and phosphodiesterase inhibitors on human sperm motility

The effects of cyclic adenosine monophosphate (cAMP), MnCl2, caffeine, and theophylline at concentrations of 10 mM on human sperm motility and forward migration in vitro were tested. cAMP was effective in activating human spermatozoal motility and forward migration after incubation with the spermatozoa for 3 hr or more and 5 hr, respectively, whereas caffeine and theophylline were effective in activating sperm motility after incubation with the spermatozoa for 1 hr or more. Caffeine and theophylline significantly activated sperm forward migration only after incubation with the sperm for 5 hr. MnCl2, a potent sperm adenylate cyclase activator, had no significant effect in improving human sperm motility and forward migration.