Calcium influx mediates the voltage-dependence of sperm entry into sea urchin eggs

David H. McCulloh, Pedro I. Ivonnet, David Landowne, Edward L. Chambers

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Sperm entry was monitored in voltage-clamped sea urchin eggs following insemination in a variety of artificial seawaters. In regular seawater, maintaining the membrane potential at increasingly negative values progressively inhibits sperm entry. Reducing [Ca2+]o relieves the inhibition, shifting the sperm entry vs voltage relationship toward more negative potentials. Raising [Ca2+]o shifts the relationship in the other direction. Large changes in [Na+]o or [Mg2+]o do not affect sperm entry although changing [Na+]o dramatically changes the currents following sperm attachment. Applying one of seven different calcium channel blockers or replacing Ca2+ with Ba2+ or Sr2+ or microinjecting calcium chelators into the cytoplasm relieves the block to sperm entry at negative potentials. We conclude that the block to sperm entry at negative potentials is mediated by calcium which crosses the membrane and acts at an intracellular site. (C) 2000 Academic Press.

Original languageEnglish (US)
Pages (from-to)449-462
Number of pages14
JournalDevelopmental Biology
Volume223
Issue number2
DOIs
StatePublished - Jul 15 2000

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology
  • Cell Biology

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