Inositol 1,4,5-trisphosphate-induced calcium mobilization is localized in Xenopus oocytes

Proc R Soc Lond B Biol Sci. 1989 Dec 22;238(1292):235-43. doi: 10.1098/rspb.1989.0079.

Abstract

Injection of inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) into the animal pole of Xenopus oocytes induced membrane depolarization due to the internal mobilization of calcium, which activates a chloride conductance. Repetitive injections of Ins(1,4,5)P3 results in desensitization probably as a result of depletion of the internal store of calcium. Desensitization was restricted to the region surrounding the site of injection. Injection of Ins(1,4,5)P3 at one position induced desensitization, which failed to spread to a neighbouring region (ca. 200 microns away). Even when sufficient Ins(1,4,5)P3 was injected to induce calcium oscillations, there was still no evidence for the effects of Ins(1,4,5)P3 spreading to neighbouring regions. The fact that periodic calcium transients could also be established by the repetitive injection of small amounts of Ins(1,4,5)P3 suggests that calcium oscillations may also be localized. It is concluded that the Ins(1,4,5)P3-sensitive store of calcium comprises separate local compartments that can be activated independently of each other.

MeSH terms

  • Animals
  • Calcium / physiology*
  • Cell Membrane / drug effects
  • Cell Membrane / physiology
  • Female
  • Inositol 1,4,5-Trisphosphate / administration & dosage
  • Inositol 1,4,5-Trisphosphate / pharmacology*
  • Membrane Potentials / drug effects
  • Microinjections
  • Oocytes / drug effects
  • Oocytes / physiology*
  • Xenopus laevis

Substances

  • Inositol 1,4,5-Trisphosphate
  • Calcium