The role of ryanodine-sensitive Ca2+ stores in the Ca2+ oscillation machine of human oocytes

• Type: Article in International Scientific Journal
• Date: 1996

Authors

sousa, m (Author) ICBAS; barros, a (Author) FMUP; Tesarik, J (Author) Other

Journal

Title: Molecular Human Reproduction

Vol. 2

Pages: 265-272

ISSN: 1360-9947

Publisher: Oxford University Press

Indexing

Scopus - 47 Citations

Other information

Authenticus ID: P-007-717

Abstract (EN): This study was undertaken to localize ryanodine-sensitive Ca2+ stores in human oocytes and to evaluate their role in the Ca2+ oscillations responsible for oocyte activation at fertilization. The addition of ryanodine provoked a Ca2+ discharge from stores localized throughout the ooplasm with the exception of the cortical and subcortical peripheral regions. The ryanodine-induced discharge was typically followed by a short series of Ca2+ oscillations that only involved the cytoplasmic region populated by the ryanodine-sensitive stores. In contrast, the Ca2+ oscillations induced by the thiol reagent thimerosal or by spermatozoa at fertilization were of a much longer duration and also involved ryanodine-insensitive stores. Presumably, these ryanodine-insensitive stores are sensitive to inositol 1,4,5-trisphosphate (InsP3). The addition of ryanodine to oocytes during ongoing thimerosal- or sperm-induced Ca2+ oscillations inhibited the oscillations. These data suggest a co-operation between the ryanodine-sensitive and ryanodine-insensitive stores in maintaining the sperm-induced Ca2+ oscillations. In this two-store oscillation model, each periodic [Ca2+]i increase is triggered by a Ca2+ discharge from the peripheral, InsP3-sensitive stores inducing Ca2+-induced Ca2+ release from the ryanodine-sensitive stores. However, the pacemaker frequency of the Ca2+ discharges from the InsP3-sensitive stores is conditioned by the actual physiological state of the ryanodine-sensitive stores. © European Society for Human Reproduction and Embryology.

Language: English

Type (Professor's evaluation): Scientific