Grosso A, Jaquet P, Brawand P, De Sousa R C
Department of Physiology, Centre Médical Universitaire, Geneva, Switzerland.
Am J Physiol. 1994 Jun;266(6 Pt 1):C1577-85. doi: 10.1152/ajpcell.1994.266.6.C1577.
We showed recently that, in toad skins preexposed to Hg, water permeability is high in SO4-Ringer and low in Cl-Ringer. This anion effect was further investigated in Hg-treated skins and bladders of toads (Bufo marinus) in a variety of experimental conditions, including glutaraldehyde fixation and stimulation by vasopressin (VP) or isoproterenol (IP). In fixed bladders either unstimulated or stimulated with VP, net water flow (Jw) in SO4-Ringer [Jw (SO4)] was always significantly higher than Jw in Cl [Jw (Cl)]; the same applies to fixed toad skins, either unstimulated or stimulated with IP. In unfixed isolated toad epidermis challenged with IP before Hg exposure, Jw(SO4)/Jw(Cl) >> 1 approaching the ratio Jw (maximally stimulated)/Jw (basal). Therefore, anion-induced Jw changes were present whether Hg acted on epithelial water channels exocytosed by Hg itself or by hydrosomotic agents and suggest a switching between open and closed configurations of the channel protein. This anion effect was not abolished by glutaraldehyde and might be correlated with changes in intracellular chloride.
我们最近发现，在预先暴露于汞的蟾蜍皮肤中，硫酸根林格液中的水渗透性高，而氯离子林格液中的水渗透性低。在多种实验条件下，包括戊二醛固定以及血管加压素（VP）或异丙肾上腺素（IP）刺激，对汞处理过的蟾蜍（海蟾蜍）皮肤和膀胱中的这种阴离子效应进行了进一步研究。在未受刺激或经VP刺激的固定膀胱中，硫酸根林格液中的净水流（Jw）[Jw(SO4)]总是显著高于氯离子林格液中的Jw[Jw(Cl)]；对于未受刺激或经IP刺激的固定蟾蜍皮肤也是如此。在汞暴露前用IP刺激的未固定离体蟾蜍表皮中，Jw(SO4)/Jw(Cl) >> 1，接近Jw（最大刺激）/Jw（基础）的比值。因此，无论汞是作用于由汞自身或渗透利尿剂胞吐的上皮水通道，阴离子诱导的Jw变化都存在，这表明通道蛋白的开放和关闭构型之间存在转换。这种阴离子效应未被戊二醛消除，可能与细胞内氯离子的变化有关。
