title: The tonicity of murine epididymal spermatozoa and their permeability towards common cryoprotectants and epididymal osmolytes.
abstract: The permeability of murine cauda epididymidal spermatozoa was determined from the swelling caused by penetrating agents at isotonicity, which lies between 422 and 530 mmol/kg. Spermatozoa were permeable to a range of solutes with size <200 Da. Relative entry rates of cryoprotective agents (CPAs) were ethylene glycol approximately DMSO>propane-1,2-diol>glycerol>propane-1,3-diol. More polar compounds including major epididymal secretions were impermeant. None of the compounds entered spermatozoa through quinine-sensitive channels; rather, quinine increased the size of solute-swollen spermatozoa, suggesting that regulatory volume decrease and osmolyte loss occurred under these conditions. Volume responses to lowered osmolality revealed a greater volume-regulating ability of spermatozoa from the B6D2F1 strain than the C57BL6 strain. As the former strain displays better post-thaw fertility, their spermatozoa may have greater osmolyte loads enabling them to cope better with osmotic stress. Inadequate volume regulation, due to CPA-induced osmolyte loss, may affect post-thaw fertility. Knowing the permeability towards cryoprotectants will help to make a better choice of CPAs that are less damaging to sperm during cryopreservation.
authors.affiliation: Institute of Reproductive Medicine of the University, Domagkstrasse 11, D-48129 Münster, Germany. trevorg.cooper@ukmuenster.de
authors.forename: T G
authors.initials: TG
authors.lastname: Cooper
authors.forename: J P
authors.initials: JP
authors.lastname: Barfield
authors.forename: C H
authors.initials: CH
authors.lastname: Yeung
mesh_terms: D000818:Animals; D002463:Cell Membrane Permeability / Q000187:drug effects; D015925:Cryopreservation; D003451:Cryoprotective Agents / Q000494:pharmacology*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004822:Epididymis; D019855:Ethylene Glycol / Q000494:pharmacology; D005990:Glycerol / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D009995:Osmosis; D011409:Propylene Glycols / Q000494:pharmacology; D012662:Semen Preservation; D013045:Species Specificity; D013081:Sperm Motility / Q000187:drug effects; D013094:Spermatozoa / Q000187:drug effects*
chemical_list: D003451:Cryoprotective Agents; D011409:Propylene Glycols; D019855:Ethylene Glycol; D005990:Glycerol; D004121:Dimethyl Sulfoxide