Gougoux A, Vinay P, Lemieux G, Goldstein M, Stinebaugh B, Halperin M
Can J Physiol Pharmacol. 1983 Jan;61(1):35-42. doi: 10.1139/y83-004.
The renal medulla can play an important role in acid excretion by modulating both hydrogen ion secretion in the medullary collecting duct and the medullary PNH3. The purpose of these experiments was to characterize the intrarenal events associated with ammonium excretion in acute acidosis. Cortical events were monitored in two ways: first, the rates of glutamine extraction and ammoniagenesis were assessed by measuring arteriovenous differences and the rate of renal blood flow; second, the biochemical response of the ammoniagenesis pathway was examined by measuring glutamate and 2-oxoglutarate, key renal cortical metabolites in this pathway. There were no significant differences noted in any of these cortical parameters between acute respiratory and metabolic acidosis. Despite a comparable twofold rise in ammonium excretion in both cases, the urine pH, PNH3, and the urine minus blood PCO2 difference (U-B PCO2) were lower during acute hypercapnia. In these experiments, the urine PCO2 was 34 mmHg (1 mmHg = 133.322 Pa) lower than that of the blood during acute respiratory acidosis while the U-B PCO2 was 5 +/- 3 mmHg in acute metabolic acidosis. Thus there were significant differences in medullary events during these two conditions. Although the urine pH is critical in determining ammonium excretion in certain circumstances, these results suggest that regional variations in the medullary PNH3 can modify this relationship.
肾髓质可通过调节髓质集合管中的氢离子分泌以及髓质中的PNH3，在酸排泄中发挥重要作用。这些实验的目的是描述急性酸中毒时与铵排泄相关的肾内事件。通过两种方式监测皮质事件：第一，通过测量动静脉差异和肾血流量来评估谷氨酰胺提取率和氨生成率；第二，通过测量谷氨酸和2-氧代戊二酸（该途径中的关键肾皮质代谢物）来检查氨生成途径的生化反应。在急性呼吸性酸中毒和代谢性酸中毒之间，这些皮质参数均未发现显著差异。尽管在这两种情况下铵排泄均有类似的两倍增长，但在急性高碳酸血症期间，尿液pH值、PNH3以及尿液与血液的PCO2差值（U-B PCO2）较低。在这些实验中，急性呼吸性酸中毒期间尿液PCO2比血液低34 mmHg（1 mmHg = 133.322 Pa），而急性代谢性酸中毒时U-B PCO2为5±3 mmHg。因此，在这两种情况下髓质事件存在显著差异。虽然在某些情况下尿液pH值对确定铵排泄至关重要，但这些结果表明髓质PNH3的区域差异可改变这种关系。
