Calcium wave evoked by activation of endogenous or exogenously expressed receptors in Xenopus oocytes

Gary Brooker, Takashi Seki, Dennis Croll, Claes Wahlestedt

Research output: Contribution to journalArticle

55 Scopus citations

Abstract

The mRNA encoding the cloned substance K receptor was microinjected into Xenopus laevis oocytes. After expression of the mRNA, Ca2+ was imaged in the oocytes with a digital imaging fluorescence microscopy system using the Ca2+-sensitive dyes fura-2 and fluo-3. Application of substance K caused a dose-related wave of Ca2+ mobilization to spread from a focus and to elevate the Ca2+ concentration in the oocyte. Activation of endogenous muscarinic or angiotensin II receptors in noninjected oocytes evoked a similar response. The Ca2+ rise in oocytes induced by substance K was due to internal Ca2+ mobilization and was independent of external Ca2+, since it occurred in Ca2+-free medium fortified with 2 mM EGTA. The Ca2+ imaging was well correlated with ion current measurements of voltage-clamped oocytes. Imaging, in addition to detecting the spatial spread of Ca2+ across the cell, was at least is sensitive as voltage clamping and much faster when screening oocytes for the expression of receptor mRNAs that stimulate Ca2+ mobilization. While it is known that fertilization of Xenopus eggs causes a spreading wave of Ca2+ mobilization, we found that activation of either native or newly expressed receptors in oocytes causes a similar change in Ca2+ distribution.

Original languageEnglish (US)
Pages (from-to)2813-2817
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume87
Issue number7
DOIs
StatePublished - Apr 1990

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Keywords

  • Acetylchoiine receptors
  • Angiotensin II receptors
  • Calcium imaging
  • Fura-2 fluorescence microscopy
  • Substance K receptors

ASJC Scopus subject areas

  • Genetics
  • General

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