Objectives: 

Cell volume alteration plays an important role in regulation of key cellular functions, including metabolism, protein synthesis, gene expression, proliferation and cell death. A fundamental property of animal cells is the ability to regulate their own volume. Under hypotonic stress the cells can readjust their volume after transient osmotic swelling by a mechanism known as regulatory volume decrease (RVD). The nature of the regulatory mechanisms governing the volume changes in oocyte during RVD is not clear. Glycine and taurine have been proposed to function as an organic osmolytes to provide intracellular osmotic support and control cell volume. The aim of this study was to investigate the glycine/taurine influence on kinetics of mouse oocyte osmotic response under hypotonic stress.

Materials: 

The keeping of the intact volume of mouse oocyte was based on freeze-drying technique. The hypotonicity was created by replacing 140mM NaCl in Dulbecco`s solution with 70mM NaCl. Oocytes were exposed for 60 minutes in the hypotonic conditions. The similar procedure was employed for Dulbecco`s containing 10 mM glycine or taurine. Osmotic adaptation in oocyte has been studied employing the direct measurement of cell volume with laser scanning microscopy followed by three-dimensional reconstruction. A Z-stack of optical sections was obtained in a confocal microscope (Leica, Germany). 3-DR was performed in the 3ds max medium.

Results: 

Our data indicate that hypoosmotic incubation for 20 minutes resulted in the swelling peak of oocyte volume: 221±15 pl. After 60 minute exposure the cell volume was recovered to 175±12 pl vs. 214±11 pl and 215±13 pl in hypotonic Dulbecco`s with 10 mM glycine or taurine, respectively.

Conclusions: 

In the given research it was shown that taurine and glycine extracellularly abolished the regulatory volume decrease in mouse oocyte. It allows us to suggest that the amino acids transport is involved in volume regulation in mouse oocytes.