Aim: 

Early preimplantation mouse conceptuses are susceptible to the detrimental effects of anisotonic conditions. Taurine has been proposed to function as an organic osmolyte and to provide intracellular osmotic support and maintain cell volume. The goal of this study was to investigate taurine influence on the kinetics of mouse oocyte osmotic response under hypotonic stress.

Methods: 

The keeping of the intact volume of mouse oocyte was based on freeze-drying technique. Osmotic adaptation in cell has been studied employing the direct measurement of cell volume with laser scanning microscopy followed by three-dimensional reconstruction. 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 taurine (Sigma, USA). A Z-stack of optical sections was obtained in a confocal microscope (Leica, Austria). 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 (these and all results below are presented as the mean and the standard deviation). After 60 minute exposure the cell volume was recovered to initial level 141±12 pl vs. 215±13 pl in hypotonic Dulbecco's with taurine.

Conclusion: 

Long-term hypoosmotic shock results in the mouse oocyte volume recovery. Cell volume regulatory decrease is abolished after incubation in hypotonic Dulbecco's containing taurine. Thus, the b-amino acid transporter seems to be involved in volume regulation in mouse oocytes.