Piermarini P M, Evans D H
Department of Zoology, University of Florida, Gainesville, FL 32611, USA.
J Exp Biol. 2000 Oct;203(Pt 19):2957-66. doi: 10.1242/jeb.203.19.2957.
Changes in Na(+)/K(+)-ATPase activity and abundance associated with environmental salinity were investigated in the gills and rectal gland of the Atlantic stingray Dasyatis sabina. Using a ouabain-specific ATPase assay and western blotting, we found that stingrays from fresh water had the highest activity and highest relative abundance of Na(+)/K(+)-ATPase in the gills. Using immunohistochemistry, we also found that gills from freshwater stingrays had the greatest number of Na(+)/K(+)-ATPase-rich cells. When freshwater stingrays were acclimated to sea water for 1 week, the activity and abundance of Na(+)/K(+)-ATPase and the number of Na(+)/K(+)-ATPase-rich cells decreased in the gills. In seawater stingrays, the branchial activity and abundance of Na(+)/K(+)-ATPase and the number of Na(+)/K(+)-ATPase-rich cells were further reduced. In rectal glands, the activity and abundance of Na(+)/K(+)-ATPase were lower in freshwater animals than in seawater-acclimated and seawater stingrays, both of which had equivalent levels. These findings suggest that salinity-associated changes in gill and rectal gland Na(+)/K(+)-ATPase activity are due to changes in the abundance of Na(+)/K(+)-ATPase. We conclude that the gills may be important for active ion uptake in fresh water, while the rectal gland is important for active NaCl excretion in sea water. The results from this study are the first to demonstrate an effect of environmental salinity on Na(+)/K(+)-ATPase expression in the gills and rectal gland of an elasmobranch.
研究了与环境盐度相关的钠钾ATP酶活性和丰度变化，该研究以大西洋黄貂鱼（Dasyatis sabina）的鳃和直肠腺为对象。通过哇巴因特异性ATP酶测定和蛋白质免疫印迹法，我们发现来自淡水的黄貂鱼鳃中钠钾ATP酶的活性和相对丰度最高。通过免疫组织化学方法，我们还发现淡水黄貂鱼的鳃中富含钠钾ATP酶的细胞数量最多。当淡水黄貂鱼适应海水1周后，鳃中钠钾ATP酶的活性、丰度以及富含钠钾ATP酶的细胞数量均减少。在海水黄貂鱼中，鳃中钠钾ATP酶的活性、丰度以及富含钠钾ATP酶的细胞数量进一步减少。在直肠腺中，淡水动物的钠钾ATP酶活性和丰度低于适应海水的动物和海水黄貂鱼，而后两者的水平相当。这些发现表明，鳃和直肠腺中与盐度相关的钠钾ATP酶活性变化是由于钠钾ATP酶丰度的改变。我们得出结论，鳃对于淡水环境中的主动离子摄取可能很重要，而直肠腺对于海水中的主动氯化钠排泄很重要。这项研究的结果首次证明了环境盐度对板鳃亚类动物鳃和直肠腺中钠钾ATP酶表达的影响。
