Cell volume regulation by the mouse zygote: mechanism of recovery from a volume increase
Séguin, D.G.; Baltz, J.M.
American Journal of Physiology 272(6 Pt 1): C1854-C1861
1997
ISSN/ISBN: 0002-9513 PMID: 9227414 Document Number: 481100
Mouse zygotes regulate their volumes after cell swelling. This regulatory volume decrease (RVD) is rapid and complete. RVD in zygotes was inhibited by K+ or Cl- channel blockers, indicating the participation of such channels in volume recovery. The channels are separate entities, as indicated by the ability of the cation ionophore gramicidin to restore RVD when K+ channels are blocked but not when Cl- channels are blocked. Intracellular Ca-2+ concentration increased with cell swelling. Nevertheless, RVD occurred normally in zygotes loaded with the Ca-2+ chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, which prevented Ca-2+ from increasing above its normal resting concentration. Thus an increase in intracellular Ca-2+ is not necessary for zygote RVD; consistent with this, inhibitors of Ca-2+-activated K+ channels had little or no effect on RVD. RVD in zygotes was also completely inhibited by millimolar amounts of extracellular ATP. ATP has been shown to inhibit current passed by the volume-sensitive organic osmolyte-Cl- channel in other cells, and thus zygotes may have such a channel participating in RVD.