Wall S M
Division of Renal Diseases and Hypertension, University of Texas, Medical School at Houston 77030, USA.
Miner Electrolyte Metab. 1996;22(5-6):311-7.
Ammonium (NH4+) excretion varies appropriately with changes in acid-base balance and represents the major regulatable component of net acid excretion. The transport of ammonium can occur by 'diffusion trapping', or active H+ secretion in parallel with passive NH3 diffusion. In addition, direct NH4+ transport is important in many nephron segments. Since NH4+ and K+ have a similar hydrated radius, these ions share common transport pathways in many renal and nonrenal cell types. For example, these ions compete for a common binding site on the Na,K-ATPase. In addition to Na+ pump-mediated NH4+ transport, the Na,K-ATPase generates an electrochemical gradient across the cell membrane which affects other H+ and NH4+ transport pathways. In this review, the role of the Na+ pump on each of these renal ammonium transport mechanisms will be reviewed.
铵（NH4+）排泄会随着酸碱平衡的变化而适当地改变，并且是净酸排泄的主要可调节成分。铵的转运可通过“扩散捕获”发生，或者通过主动分泌H+并伴随NH3的被动扩散进行。此外，直接的NH4+转运在许多肾单位节段中都很重要。由于NH4+和K+具有相似的水合半径，这些离子在许多肾和非肾细胞类型中共享共同的转运途径。例如，这些离子竞争Na，K-ATP酶上的一个共同结合位点。除了Na+泵介导的NH4+转运外，Na，K-ATP酶还会在细胞膜上产生一个电化学梯度，这会影响其他H+和NH4+的转运途径。在这篇综述中，我们将探讨Na+泵在这些肾铵转运机制中的作用。
