Acceleration of intracellular calcium waves in Xenopus oocytes by calcium influx.
Many cell membrane receptors stimulate the phosphoinositide (PI) cycle, which produces complex intracellular calcium signals that regulate diverse processes such as secretion and transcription. A major messenger of this cycle, inositol 1,4,5-triphosphate (IP3), stimulates its receptor channel on the endoplasmic reticulum to release calcium into the cytosol. Activation of the PI cycle also induces calcium influx, which refills the intracellular calcium stores. Confocal microscopy was used to show that receptor-activated calcium influx, enhanced by hyperpolarization, modulates the frequency and velocity of IP3-dependent calcium waves in Xenopus laevis oocytes. These results demonstrate that transmembrane voltage and calcium influx pathways may regulate spatial and temporal patterns of IP3-dependent calcium release.
Department of Pharmacology, Mayo Foundation, Rochester, MN 55905.
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Girard
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Clapham
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels; D005260:Female; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007295:Inositol Phosphates / Q000494:pharmacology*; D008564:Membrane Potentials; D008856:Microscopy, Fluorescence; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism*; D009946:Organothiophosphorus Compounds / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear; D011976:Receptors, Muscarinic / Q000378:metabolism*; D015290:Second Messenger Systems; D015398:Signal Transduction; D014982:Xenopus laevis
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007295:Inositol Phosphates; D009946:Organothiophosphorus Compounds; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D011976:Receptors, Muscarinic; C066055:inositol 1,4-bisphosphate 5-phosphorothioate; D001285:Atropine; D000109:Acetylcholine; D002118:Calcium