Ionic bases of the membrane potential and intracellular pH changes induced by speract in swollen sea urchin sperm

FEBS Lett. 1993 Aug 23;329(1-2):210-4. doi: 10.1016/0014-5793(93)80223-h.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism
  • Calcium / pharmacology
  • Cell Membrane Permeability
  • Cobalt / pharmacology
  • Hydrogen-Ion Concentration
  • Hypotonic Solutions
  • Magnesium / metabolism
  • Male
  • Membrane Potentials
  • Nickel / pharmacology
  • Oligopeptides / pharmacology*
  • Ouabain / pharmacology
  • Sea Urchins*
  • Signal Transduction
  • Sodium / metabolism
  • Sodium / pharmacology
  • Spermatozoa / physiology*


  • Hypotonic Solutions
  • Oligopeptides
  • Cobalt
  • Ouabain
  • speract
  • Nickel
  • Sodium
  • Magnesium
  • Calcium