title: Ionic bases of the membrane potential and intracellular pH changes induced by speract in swollen sea urchin sperm.
abstract: Signal transduction initiated by the egg peptide, speract, in sea urchin sperm is not fully understood. Hypotonically swollen sperm are a suitable model to study peptide signal transduction. Ion substitution experiments now indicate (i) that the permeability to Na+, Ca2+, and Mg2+ contributes to the sperm resting membrane potential; (ii) the repolarization induced by nM concentrations of speract is Na+ dependent and mediated by an as yet unidentified channel; (iii) the depolarization triggered by nM concentrations of speract involves Ca2+ channels since it is Ca(2+)-dependent and blocked by Co2+ and Ni2+, two Ca2+ channel blockers; (iv) hyperpolarizing swollen sperm with valinomycin increases intracellular pH (pHi) in the same way as speract, thus the speract-induced hyperpolarization may be responsible for the pHi increase.
authors.affiliation: Instituto de Biotechnología, Universidad Nacional Autónoma de México, Cuernavaca.
authors.forename: E
authors.initials: E
authors.lastname: Reynaud
authors.forename: L
authors.initials: L
authors.lastname: De de La Torre
authors.forename: O
authors.initials: O
authors.lastname: Zapata
authors.forename: A
authors.initials: A
authors.lastname: Liévano
authors.forename: A
authors.initials: A
authors.lastname: Darszon
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002463:Cell Membrane Permeability; D003035:Cobalt / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007038:Hypotonic Solutions; D008274:Magnesium / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials; D009532:Nickel / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology*; D010042:Ouabain / Q000494:pharmacology; D012617:Sea Urchins; D015398:Signal Transduction; D012964:Sodium / Q000378:metabolism / Q000494:pharmacology; D013094:Spermatozoa / Q000502:physiology*
chemical_list: D007038:Hypotonic Solutions; D009842:Oligopeptides; D003035:Cobalt; D010042:Ouabain; C028364:speract; D009532:Nickel; D012964:Sodium; D008274:Magnesium; D002118:Calcium