title: K+ activity and regulation of intracellular pH in the sea urchin egg during fertilization.
abstract: Fertilization of the sea urchin egg is accompanied by changes in intracellular ion activities and transmembrane fluxes, which regulate the sequence of biochemical events of metabolic derepression. Changes in intracellular K+ activity during fertilization have been controversial and here we report our measurements using intracellular K+-sensitive microelectrodes. A small, but statistically significant, transient rise in internal K+ activity was detected during the first 10 min of fertilization. Since this change in K+ activity was ouabain sensitive, intracellular K+ activity in the fertilized egg appears to be regulated by the increased Na+, K+ ATPase activity, rather than the previously suggested K+ decompartmentalization. Increasing external K+ concentration was found to stimulate ouabain-sensitive alkalinization in the fertilized egg. The data are consistent with the possibility that Na+, K+ ATPase may regulate cytoplasmic pH by recycling Na+ that enters the cell through Na+-H+ antiport.
authors.affiliation: Department of Zoology, Iowa State University, Ames 50011.
authors.forename: S S
authors.initials: SS
authors.lastname: Shen
authors.forename: A L
authors.initials: AL
authors.lastname: Sui
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D004594:Electrophysiology / Q000379:methods; D005260:Female; D005306:Fertilization; D006706:Homeostasis; D006863:Hydrogen-Ion Concentration; D008564:Membrane Potentials; D008839:Microelectrodes; D010042:Ouabain / Q000494:pharmacology; D010063:Ovum / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000502:physiology*; D012617:Sea Urchins; D017923:Sodium-Hydrogen Exchangers
chemical_list: D002352:Carrier Proteins; D017923:Sodium-Hydrogen Exchangers; D010042:Ouabain; D011188:Potassium