Cyto B dependent and ouabain insensitive Regulatory Volume Decrease in bicellular mouse embryo

Abstract

Mouse single cell embryos exhibit robust Regulatory Volume Decrease (RVD). In what manner the very early mammalian embryo following zygote stage is appreciably altered by the anisotonic extracellular solution is, as yet, totally unclear. Little attention was paid to this direction since there was no way to deter mine the blastomere volume. This work has served to quantitatively investigate the osmotic response of bicel lular mouse embryos employing Laser Scanning Microtomography (LSM) followed with three dimensional reconstruction (3 DR). We have shown that bicellular mouse embryos in hypotonic Dulbecco's experience RVD. Embryonic cells subjected to hyposmolar exhibit rapid osmotic swelling followed by gradual shrinking back toward their original volume. The van 't Hoff law defines swelling phase with the effective hydraulic con ductivity of 0.3 micron ⋅ min -1 ⋅ atm -1 . Water release during RVD in bicellular mouse embryos is abolished by Cytochalasin B (Cyto B) and the volume recovery is insensitive to ouabain treatment.

Glycine blocks the regulatory volume response of mouse oocytes to hypoosmotic stress

“…3). When considering this effect, the similar non osmotic effects of ATP [1] and cytochalasin B should be noted [15]. In the case of ATP, the inhibition of the Cl -channel activated under hypotonic conditions is discussed.…”