Sands J M, Knepper M A, Spring K R
Am J Physiol. 1986 Sep;251(3 Pt 2):F475-84. doi: 10.1152/ajprenal.1986.251.3.F475.
The renal papillary surface epithelium is exposed to pelvic urine on its apical surface and to inner medullary interstitium on its basolateral surface. To investigate transport in this epithelium, we dissected it free from the renal papilla of rabbits and mounted it in a chamber that allowed both sides to be bathed independently. Cell volume was measured at 25 degrees C utilizing computerized quantitative microscopy. Addition of ouabain (10(-4) M) to the basolateral solution induced a 20% volume increase. This volume increase was completely inhibited by the removal of apical bath NaCl, Na+, K+, or Cl- but not by the removal of urea. Bumetanide, down to 10(-9) M in the apical bath, completely inhibited the ouabain-induced swelling. Changes in apical bath osmolality, resulting from addition or removal of NaCl, caused cell volume changes that were greater than could be accounted for by osmotic water flow alone. This hyperresponse was blocked by bumetanide and was stimulated by vasopressin (10(-8) M). These observations are consistent with the presence of Na-K-ATPase in the basolateral membrane and a bumetanide-sensitive, vasopressin-responsive Na-K-Cl co-transporter in the apical membrane.
肾乳头表面上皮细胞的顶端表面暴露于肾盂尿液中，基底外侧表面暴露于内髓质间质中。为了研究该上皮细胞的转运情况，我们将其从兔肾乳头分离出来，并将其置于一个能使两侧独立进行灌流的小室中。在25摄氏度下利用计算机定量显微镜测量细胞体积。向基底外侧溶液中添加哇巴因（10^(-4) M）会导致细胞体积增加20%。去除顶端灌流液中的NaCl、Na⁺、K⁺或Cl⁻可完全抑制这种体积增加，但去除尿素则无此作用。顶端灌流液中布美他尼浓度低至10^(-9) M时，可完全抑制哇巴因诱导的肿胀。添加或去除NaCl导致顶端灌流液渗透压改变，引起的细胞体积变化大于仅由渗透水流所解释的变化。这种高反应性被布美他尼阻断，并被血管加压素（10^(-8) M）刺激。这些观察结果与基底外侧膜中存在钠钾ATP酶以及顶端膜中存在对布美他尼敏感、对血管加压素反应的钠钾氯共转运体一致。
