Farman N, Vandewalle A, Bonvalet J P
Am J Physiol. 1982 Jan;242(1):F63-8. doi: 10.1152/ajprenal.1982.242.1.F63.
Microbiochemical methods were applied to proximal tubules (PCT) and a mixture of distal and cortical collecting tubules (D + C) of rabbit kidney in order to define aldosterone binding sites. For each experiment, after incubation of kidney pyramids with [3H]aldosterone ([3H]A), either alone or in the presence of an excess unlabeled A, 100-150 mm of both categories of tubules were microdissected using collagenase. Specific binding was determined on the nuclear fraction of each sample. Aldosterone concentrations ranged from 2 X 10(-9) to 4.5 X 10(-8) M. No specific binding was detectable in PCT. Specific binding in D + C increased rapidly as a function of [3H]A concentration up to 5 X 10(-9) M and then more slowly. No plateau was reached. Both the absence of saturation of the binding curve and the curvilinear aspect of the Scatchard plot suggested the presence of two binding sites, one of high affinity, presumably a mineralocorticoid site, and the other of lower affinity, possibly a glucocorticoid site. These experiments suggest that the distal structures of the nephron, located in the cortex, are the main sites of binding of aldosterone and contain a high number of specific binding sites for this hormone.
为了确定醛固酮结合位点，运用微生物化学方法对兔肾近端小管（PCT）以及远端和皮质集合小管的混合物（D + C）进行研究。在每个实验中，用[3H]醛固酮（[3H]A）孵育肾锥体，[3H]A单独使用或在过量未标记的A存在的情况下，使用胶原酶显微解剖出两类小管各100 - 150毫米。在每个样本的核部分测定特异性结合。醛固酮浓度范围为2×10^(-9)至4.5×10^(-8)M。在PCT中未检测到特异性结合。在D + C中的特异性结合随着[3H]A浓度增加至5×10^(-9)M时迅速增加，然后增加得更慢。未达到平台期。结合曲线缺乏饱和度以及Scatchard图的曲线特征均表明存在两个结合位点，一个具有高亲和力，推测为盐皮质激素位点，另一个具有较低亲和力，可能为糖皮质激素位点。这些实验表明，位于皮质的肾单位远端结构是醛固酮的主要结合位点，并且含有大量该激素的特异性结合位点。
