Kleyman T R, Smith P R, Benos D J
Department of Medicine, University of Pennsylvania, Philadelphia.
Am J Physiol. 1994 Apr;266(4 Pt 1):C1105-11. doi: 10.1152/ajpcell.1994.266.4.C1105.
The toad urinary bladder and epithelial cell lines derived from the urinary bladder, including TBM, serve as model systems for the study of transepithelial Na+ transport. We examined biochemical characteristics of epithelial Na+ channels in toad urinary bladder and TBM cells and their cellular localization in the urinary bladder. The radiolabeled amiloride analogue [3H]benzamil bound to a single class of high-affinity binding sites in membrane vesicles from toad urinary bladder with a dissociation constant (Kd) of 10 nM. Photoactive benzamil analogues specifically labeled a 135,000-Da polypeptide in toad urinary bladder and TBM cells. A monoclonal anti-Na+ channel antibody directed against the amiloride-binding component of the channel specifically recognized a 135,000-Da polypeptide in TBM cells. Polyclonal anti-Na+ channel antibodies generated against purified bovine epithelial Na+ channel specifically recognized a 235,000-Da polypeptide in toad urinary bladder and localized Na+ channels to the apical plasma membrane of urinary bladder epithelial cells. The biochemical characteristics and the cellular localization of epithelial Na+ channels in toad urinary bladder are similar to those previously described in mammalian kidney and in the A6 cell line.
蟾蜍膀胱以及源自膀胱的上皮细胞系，包括TBM细胞系，可作为研究跨上皮Na⁺转运的模型系统。我们研究了蟾蜍膀胱和TBM细胞中上皮Na⁺通道的生化特性及其在膀胱中的细胞定位。放射性标记的氨氯地平类似物[³H]苯甲酰咪与蟾蜍膀胱膜囊泡中一类单一的高亲和力结合位点结合，解离常数（Kd）为10 nM。光活性苯甲酰咪类似物在蟾蜍膀胱和TBM细胞中特异性标记了一条135,000道尔顿的多肽。一种针对通道氨氯地平结合成分的单克隆抗Na⁺通道抗体在TBM细胞中特异性识别一条135,000道尔顿的多肽。针对纯化的牛上皮Na⁺通道产生的多克隆抗Na⁺通道抗体在蟾蜍膀胱中特异性识别一条235,000道尔顿的多肽，并将Na⁺通道定位到膀胱上皮细胞的顶端质膜。蟾蜍膀胱中上皮Na⁺通道的生化特性和细胞定位与先前在哺乳动物肾脏和A6细胞系中描述的相似。
