Beck J S, Laprade R, Lapointe J Y
Am J Physiol. 1994 Apr;266(4 Pt 2):F517-27. doi: 10.1152/ajprenal.1994.266.4.F517.
A common feature of sodium-reabsorbing epithelia is their ability to match salt entry to salt exit. It is recognized that a key strategy to perform this feat involves the coupling between basolateral sodium pump and potassium conductance (pump-leak coupling). In the renal proximal tubule this coupling is of major importance, as regions of this nephron segment are faced with ever-changing reabsorptive loads. An understanding of this coupling can be facilitated by critically examining those studies that have looked at the problem from the point of view of the whole cell (macroscopic studies) and of single channels (microscopic studies). An overview of such work suggests that the transduction mechanisms which are likely to effect pump-leak coupling in the renal proximal tubule involve cell volume, ATP, and pH (but not calcium). Although the relationship between ATP and potassium conductance may be relatively straightforward, the involvement of pH is likely to be only transient and that of volume remains controversial, occurring either directly though stretch-activated channels in amphibian preparations or indirectly through an as yet unidentified second messenger system in mammalian preparations.
重吸收钠的上皮细胞的一个共同特征是它们能够使盐的进入与盐的排出相匹配。人们认识到，实现这一功能的关键策略涉及基底外侧钠泵与钾电导之间的耦合（泵-漏耦合）。在肾近端小管中，这种耦合至关重要，因为该肾单位节段的各个区域面临着不断变化的重吸收负荷。通过批判性地审视那些从全细胞角度（宏观研究）和单通道角度（微观研究）研究该问题的研究，可以促进对这种耦合的理解。此类工作的概述表明，可能影响肾近端小管泵-漏耦合的转导机制涉及细胞体积、ATP和pH（但不涉及钙）。尽管ATP与钾电导之间的关系可能相对直接，但pH的参与可能只是短暂的，而细胞体积的参与仍存在争议，在两栖类制剂中可能直接通过牵张激活通道发生，在哺乳类制剂中则可能间接通过尚未确定的第二信使系统发生。
