SEGMENTAL ANALYSIS OF THE RENAL TUBULE IN BUFFER PRODUCTION AND NET ACID FORMATION
SEGMENTAL ANALYSIS OF THE RENAL TUBULE IN BUFFER PRODUCTION AND NET ACID FORMATION
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DOI：
10.1152/ajprenal.1983.244.4.f442
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发表时间：
1983-01-01
影响因子：
--
通讯作者：
TRIGG, D
中科院分区：
文献类型：
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作者：
BUERKERT, J;MARTIN, D;TRIGG, D
在Munich-Wistar大鼠的乳头和表面微穿刺被用来评估的作用，近段的浅表和髓质（JM）肾单位，远端小管浅表肾单位，和终端收集管在酸排泄。这些部分在铵生产，HCO 3-回收，和净酸形成的相对作用进行了评估，根据hydropenic条件和慢性酸负荷后。在这两种情况下，两种肾单位的近端段是氨产生和HCO 3回收的主要部位。该片段对净酸形成的贡献仅在酸中毒期间显著。远曲小管以外的节段似乎是酸形成的主要部位。原位pH值测量值较低，在这些肾单位段，甚至下降后，诱导酸中毒。氨似乎进入远端小管末端和集合管底部之间的液体。JM肾单位的Henle袢弯曲附近的体内pH测量值比浅表肾单位的近端小管末端附近的pH值更碱性。这种pH值的差异可能会使铵解离，从而使氨移出小管腔并进入集合管流体，在那里它被质子化并重新捕获。这一过程通过摄入慢性酸负荷而增强。
Papillary and surface micropuncture in Munich-Wistar rats was used to assess the role of proximal segments of superficial and juxtamedullary (JM) nephrons, the distal tubule of superficial nephrons, and the terminal collecting duct in acid excretion. The relative role of these segments in ammonium production, HCO3- reclamation, and net acid formation was assessed under hydropenic conditions and after a chronic acid load. In these 2 settings the proximal segment of both kinds of nephrons is the major site of ammonium production and HCO3- reclamation. This segment''s contribution to net acid formation was only significant during acidosis. Segments beyond the distal tubule appear to be the major site of acid formation. In situ pH measurements were lower in these nephron segments and fell even more after the induction of an acidosis. Ammonia appears to enter fluid between the end of the distal tubule and the base of the collecting duct. In vivo pH measurements made near the bend of Henle''s loop of JM nephrons were more alkaline than near the end of the proximal tubule of superficial nephrons. This difference in pH may allow ammonium to dissociate, permitting the movement of ammonia out of the tubule lumen and into collecting duct fluid where it is protonated and reentrapped. This process is enhanced by the ingestion of a chronic acid load.