Molecular mechanisms of intracellular calcium excitability in X. laevis oocytes

James D. Lechleiter, David E. Clapham

Research output: Contribution to journalArticlepeer-review

112 Scopus citations


Following receptor activation in Xenopus oocytes, spiral waves of intracellular Ca2+ release were observed. We have identified key molecular elements in the pathway that give rise to Ca2+ excitability. The patterns of Ca2+ release produced by GTP-γ-S and by inositol 1,4,5-trisphosphate (IP3) are indistinguishable from receptor-induced Ca2+ patterns. The regenerative Ca2+ activity is critically dependent on the presence of IP3 and on the concentration of intracellular Ca2+, but is independent of extracellular Ca2+. Broad regions of the intracellular milieu can be synchronously excited to initiate Ca2+ waves and produce pulsating foci of Ca2+ release. By testing the temperature dependence of wavefront propagation, we provide evidence for an underlying process limited by diffusion, consistent with the elementary theory of excitable media. We propose a model for intracellular Ca2+ signaling in which wave propagation is controlled by IP3-mediated Ca2+ release from internal stores, but is modulated by the cytoplasmic concentration and diffusion of Ca2+.

Original languageEnglish (US)
Pages (from-to)283-294
Number of pages12
Issue number2
StatePublished - Apr 17 1992
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)


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