Role of the extracellular Ca2+ on the intracellular Ca2+ changes in fertilized and activated mouse oocytes

J Reprod Fertil. 1993 Jan;97(1):143-50. doi: 10.1530/jrf.0.0970143.


Changes in intracellular calcium concentration ([Ca2+]i) in fertilized mouse oocytes were measured using the calcium-sensitive dye, fura-2. After fertilization, an initial long-lasting [Ca2+]i increase was followed by a periodic [Ca2+]i increase. The periodic increase in [Ca2+]i persisted for 1 to 3 h and all fertilized oocytes extruded the second polar body within 4 h. The mean interval of periodic [Ca2+]i increase was 470 +/- 180 s (mean +/- SD). The frequency of the periodic [Ca2+]i increase depended on the extracellular calcium concentration. Verapamil and nifedipine inhibited the periodic [Ca2+]i increase. Sixty-five per cent of tested cells extruded the second polar body within 90 min of exposure to 7% ethanol. In these activated oocytes, the long-lasting [Ca2+]i increase was observed. However, no cells showed a repetitive increase in [Ca2+]i. Both release of calcium from intracellular stores and influx of extracellular calcium contribute to the increase in [Ca2+]i induced by ethanol. We conclude that the extrusion of the second polar body requires an increase in [Ca2+]i above a certain threshold level and the mobilization of calcium of both the intracellular and extracellular space in mouse oocytes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / physiology*
  • Cells, Cultured
  • Ethanol / pharmacology
  • Extracellular Space / metabolism*
  • Female
  • Fertilization / physiology*
  • Fura-2
  • Intracellular Fluid / metabolism*
  • Mice
  • Mice, Inbred Strains
  • Models, Biological
  • Nifedipine / pharmacology
  • Verapamil / pharmacology
  • Zygote / drug effects
  • Zygote / metabolism*


  • Ethanol
  • Verapamil
  • Nifedipine
  • Calcium
  • Fura-2