title: Platelet activating factor and pentoxifylline as human sperm cryoprotectants.
abstract: OBJECTIVE
  To explore whether the addition of platelet-activating factor (PAF) or pentoxifylline before cryopreservation improves the recovery of motile viable sperm and what role cyclic adenosine monophosphate (cAMP) plays in this recovery.
  
  
  METHODS
  Washed sperm was cryopreserved in the absence of and in the presence of PAF and pentoxifylline. After 2 weeks these samples were quick-thawed and evaluated before and after washing for sperm motility and other motion characteristics. Sperm viability and cAMP concentration were determined to compare the effects of these cryoprotectants.
  
  
  RESULTS
  When sperm samples were cryopreserved in the presence of PAF or pentoxifylline, an improvement in the recovery of motile sperm in unwashed and washed post-thaw samples was observed. There were 38% more motile sperm recovered with PAF and 15% more with pentoxifylline when compared with untreated samples. In comparison with the unwashed samples, sperm motility in post-thaw samples was lowered by the washing procedure. When PAF was used as a cryoprotectant, a significant improvement in the linearity and straight line velocity of the post-thaw sperm was observed. When pentoxifylline was used as a cryoprotectant, lateral head displacement was significantly improved in the post-thaw samples than in the control group. Both PAF-and pentoxifylline-treated samples contained a greater number of viable sperm than the control. The cAMP concentrations in post-thaw samples were 12-fold higher in pentoxifylline-treated samples and 4-fold higher in PAF-treated samples when compared with the untreated control. A 4-fold decrease in cAMP concentration was observed in post-thaw control samples compared with fresh-washed sperm.
  
  
  CONCLUSIONS
  The results of this study suggest that both PAF and pentoxifylline are useful cryoprotectants for the increased recovery of motile, viable sperm. Although increased recovery of motile sperm in pentoxifylline-treated samples is related to higher cAMP levels, the cryoprotective effect of PAF does not appear to be due to increased cAMP.
authors.affiliation: Department of Urology, Tulane University School of Medicine, New Orleans, Louisiana 70112-2699.
authors.forename: R
authors.initials: R
authors.lastname: Wang
authors.forename: S C
authors.initials: SC
authors.lastname: Sikka
authors.forename: K
authors.initials: K
authors.lastname: Veeraragavan
authors.forename: M
authors.initials: M
authors.lastname: Bell
authors.forename: W J
authors.initials: WJ
authors.lastname: Hellstrom
mesh_terms: D002470:Cell Survival; D003451:Cryoprotective Agents / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism; D005615:Freezing; D006801:Humans; D008297:Male; D010431:Pentoxifylline / Q000494:pharmacology*; D010972:Platelet Activating Factor / Q000494:pharmacology*; D012016:Reference Values; D013081:Sperm Motility / Q000187:drug effects; D013094:Spermatozoa / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology
chemical_list: D003451:Cryoprotective Agents; D010972:Platelet Activating Factor; D000242:Cyclic AMP; D010431:Pentoxifylline