INCREASE OF INTRACELLULAR CALCIUM IS NOT A CAUSE OF PENTOXIFYLLINE-INDUCED HYPERACTIVATED MOTILITY OR ACROSOME REACTION IN HUMAN SPERM

Objective: To investigate the effects of the phosphodiesterase inhibit or pentoxifylline on hyperactivated motility and acrosome reaction in human sperm and to determine whether its stimulatory effects occur via increased intracellular calcium levels. Design: Prospective study. Se tting: Academic tertiary care facility. Participant(s): Healthy male d onors. Intervention(s): The effects of pentoxifylline on hyperactivate d motility, acrosome reaction, and intracellular calcium were studied and compared with the effects of progesterone. Thapsigargin, a known m obilizer of intracellular calcium, also was used as positive control. Main Outcome Measure(s): Hyperactivated motility was assessed by compu ter-assisted sperm motion analysis using the HTM-IVOS, acrosome reacti on was evaluated with the fluorescent probe fluorescein isothiocyanate -labeled Pisum sativum agglutinin, and intracellular calcium was deter mined by fura-2 using spectrofluorometry. Result(s): Pentoxifylline si gnificantly increased both hyperactivated motility and acrosome reacti on. Enhancement of hyperactivated motility by pentoxifylline in the ca pacitation medium persisted for up to 5 hours after pentoxifylline was washed from the medium. It also enhanced the percentage of acrosome-r eacted spermatozoa after 4 hours of incubation. These effects occurred in the presence of a marginally significant decrease in intracellular calcium. Conclusion(s): Pentoxifylline stimulates hyperactivated moti lity and acrosome reaction in spermatozoa from fertile men. Its stimul atory effects occur through mechanism(s) other than increase in intrac ellular calcium. (C) 1998 by American Society for Reproductive Medicin e.).