RENAL SODIUM-CHANNELS - REGULATION AND SINGLE-CHANNEL PROPERTIES
RENAL SODIUM-CHANNELS - REGULATION AND SINGLE-CHANNEL PROPERTIES
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DOI：
10.1038/ki.1995.375
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发表时间：
1995-10-01
影响因子：
19.6
通讯作者：
LING, BN
中科院分区：
文献类型：
--
作者：
EATON, DC;BECCHETTI, A;LING, BN
虽然野餐或露营的人可能会觉得大自然在使动物生活（特别是节肢动物生活）适应陆地环境方面取得了太大的成功，但与海洋动物的物种数量和普查相比，陆地物种的数量和这些物种的普查是很小的。如果只考虑相对较大的生物，情况尤其如此：在陆地上，这些生物大多是脊椎动物。陆地物种相对稀少有几个原因。首先，在进化的背景下，动物入侵陆地相对较晚，因此有较少的时间来发展;但第二，陆地环境对生物体的要求与海洋环境明显不同。一个区别是，对于海洋生物来说，盐和水的摄入是相互关联的，但对于陆地动物来说，显然不是这样。因此，盐和水的平衡必须分开调节。在脊椎动物中，需要独立于水来调节盐，这导致了几种独特的适应性进化，其中之一是阿米洛利可阻断的Na+通道。阿米洛利可阻断的Na+通道是许多脊椎动物中调节Na+重吸收的主要位点。这种矢量运输的经典例子是跨青蛙皮肤的Na+吸收，但在哺乳动物中，Na+重吸收的自由控制的主要部位是远端肾单位。在远端肾单位的主要细胞中，Na+转运是一个两步过程：首先，Na+通过顶端Na+通道从管腔被动进入细胞，然后通过基底外侧Na+，K+-ATP酶从细胞向浆膜室的ATP依赖性挤出。虽然Na+转运的一些调节可能通过控制Na+，K+-ATP酶活性在基底外侧出口步骤发生，但几乎所有的Na+转运调节显然是通过控制顶端进入步骤，即阿米洛利可阻断的Na+通道。
While anyone on a picnic or campout may feel that nature has succeeded only too well in adapting animal life (particularly arthropodan life) to a terrestrial environment, the number of terrestrial species and the census of those species is small by comparison with the number of species and the census of marine animals. This is particularly true if one considers only relatively large organisms: on land, these are mostly vertebrates. There are several reasons for this relative scarcity of terrestrial species. First, in an evolutionary context, animals invaded land relatively late and consequently have had less time to develop; but second, a terrestrial environment places significantly different demands on an organism than a marine environment. One difference is that, for a marine organism, salt and water intake is coupled, yet in terrestrial animals it decidedly is not. Thus, salt and water balance must be regulated separately. In vertebrates, the necessity to regulate salt independently of water has lead to the evolution of several unique adaptations, one of which is the amiloride-block-able Na+channel. The amiloride-blockable Na+channel is the primary site for the regulation of Na+reabsorption in many vertebrates. The classical example of such vectorial transport is the uptake of Na+across frog skin, but in mammals the primary site for discretionary control of Na+reabsorption is the distal nephron. In principal cells of the distal nephron, Na+transport is a two step process: first, passive entry of Na+from the lumen into the cell through apical Na+channels followed by ATP-dependent extrusion from the cell to the serosal compartment via the basolateral Na+,K+-ATPase. While some regulation of Na+transport may take place at the basolateral exit step by controlling Na+,K+-ATPase activity, almost all regulation of Na+transport is, apparently, via control of the apical entry step, namely the amiloride-blockable Na+channel.