Ion pump ATPase inhibitors block the fertilization of zona-free mouse oocytes by acrosome-reacted spermatozoa.
The acrosome reaction was induced in nearly 100% of mouse spermatozoa with dibutyryl cyclic guanosine monophosphate (dbcGMP) before ouabain treatment. Acrosome-reacted spermatozoa could not penetrate the zona pellucida, but readily fertilized zona-free eggs. Exposure to ouabain at concentrations as low as 10(-7) M had a noticeable inhibitory effect upon fertilization. Similar results were obtained with a second ATPase inhibitor, digoxin. These results show that ion-pump inhibitors block the union of gametes which are otherwise fully competent to fertilize. These findings suggest that a membrane potential maintained by ion pumps is a necessary prerequisite for gamete fusion.
D000177:Acrosome / Q000187:drug effects; D000818:Animals; D006152:Cyclic GMP / Q000031:analogs & derivatives*; D003995:Dibutyryl Cyclic GMP / Q000494:pharmacology*; D004077:Digoxin / Q000494:pharmacology; D005260:Female; D007473:Ion Channels / Q000502:physiology*; D008297:Male; D008561:Membrane Fusion; D051379:Mice; D008815:Mice, Inbred Strains; D010042:Ouabain / Q000494:pharmacology; D013084:Sperm-Ovum Interactions / Q000187:drug effects*; D013094:Spermatozoa / Q000187:drug effects*
D007473:Ion Channels; D003995:Dibutyryl Cyclic GMP; D010042:Ouabain; D004077:Digoxin; D006152:Cyclic GMP