Free calcium in Xenopus embryos measured with ion-selective microelectrodes.
A regulatory role for intracellular free calcium has been suggested in cell division and intercellular communication via gap junctions. Previous measurements of cytoplasmic free Ca2+ during cell division and uncoupling have been made with the Ca2+-sensitive photoprotein aequorin. We now report experiments using Ca2+-sensitive microelectrodes to monitor free Ca2+ in the cells and intercellular fluid of early embryos of the amphibian Xenopus laevis. In addition to measuring basal levels, we have looked for changes in free Ca2+ during cell division and during electrical uncoupling of the normally coupled embryonic cells, induced by acidification of the intracellular medium.
D000818:Animals; D002118:Calcium / Q000032:analysis*; D002245:Carbon Dioxide / Q000494:pharmacology; D002450:Cell Communication; D002453:Cell Cycle; D002455:Cell Division; D003593:Cytoplasm / Q000032:analysis; D004625:Embryo, Nonmammalian / Q000032:analysis*; D005110:Extracellular Space / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D007365:Intercellular Junctions / Q000502:physiology; D008839:Microelectrodes; D014981:Xenopus / Q000196:embryology*
D002245:Carbon Dioxide; D002118:Calcium