Piermarini Peter M, Verlander Jill W, Royaux Ines E, Evans David H
Department of Zoology, University of Florida, Gainesville, Florida 32611, USA.
Am J Physiol Regul Integr Comp Physiol. 2002 Oct;283(4):R983-92. doi: 10.1152/ajpregu.00178.2002.
Pendrin is an anion exchanger in the cortical collecting duct of the mammalian nephron that appears to mediate apical Cl(-)/HCO3(-) exchange in bicarbonate-secreting intercalated cells. The goals of this study were to determine 1) if pendrin immunoreactivity was present in the gills of a euryhaline elasmobranch (Atlantic stingray, Dasyatis sabina), and 2) if branchial pendrin immunoreactivity was influenced by environmental salinity. Immunoblots detected pendrin immunoreactivity in Atlantic stingray gills; pendrin immunoreactivity was greatest in freshwater stingrays compared with freshwater stingrays acclimated to seawater (seawater acclimated) and marine stingrays. Using immunohistochemistry, pendrin-positive cells were detected on both gill lamellae and interlamellar regions of freshwater stingrays but were more restricted to interlamellar regions in seawater-acclimated and marine stingray gills. Pendrin immunolabeling in freshwater stingray gills was more apical, discrete, and intense compared with seawater-acclimated and marine stingrays. Regardless of salinity, pendrin immunoreactivity occurred on the apical region of cells rich with basolateral vacuolar-proton-ATPase, and not in Na(+)-K(+)-ATPase-rich cells. We suggest that a pendrin-like transporter may contribute to apical Cl(-)/HCO3(-) exchange in gills of Atlantic stingrays from both freshwater and marine environments.
Pendrin是哺乳动物肾单位皮质集合管中的一种阴离子交换蛋白，似乎在分泌碳酸氢盐的闰细胞中介导顶端Cl⁻/HCO₃⁻交换。本研究的目的是确定：1）广盐性板鳃亚纲动物（大西洋黄貂鱼，Dasyatis sabina）的鳃中是否存在pendrin免疫反应性；2）鳃中pendrin免疫反应性是否受环境盐度影响。免疫印迹法在大西洋黄貂鱼的鳃中检测到了pendrin免疫反应性；与适应海水的淡水黄貂鱼（海水适应型）和海洋黄貂鱼相比，淡水黄貂鱼中的pendrin免疫反应性最强。利用免疫组织化学方法，在淡水黄貂鱼的鳃小片和片间区域均检测到了pendrin阳性细胞，但在海水适应型和海洋黄貂鱼的鳃中，pendrin阳性细胞更多地局限于片间区域。与海水适应型和海洋黄貂鱼相比，淡水黄貂鱼鳃中的pendrin免疫标记更靠近顶端、更离散且更强。无论盐度如何，pendrin免疫反应性均出现在富含基底外侧液泡质子ATP酶的细胞顶端区域，而不出现在富含Na⁺-K⁺-ATP酶的细胞中。我们认为，一种类似pendrin的转运蛋白可能有助于淡水和海洋环境中的大西洋黄貂鱼鳃进行顶端Cl⁻/HCO₃⁻交换。
