Effects of pH and medullary blood flow on oxygen transport and sodium reabsorption in the rat outer medulla
Effects of pH and medullary blood flow on oxygen transport and sodium reabsorption in the rat outer medulla
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DOI：
10.1152/ajprenal.00572.2009
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发表时间：
2010-06-01
影响因子：
4.2
通讯作者：
Layton, Anita T.
中科院分区：
文献类型：
--
作者：
Chen, Jing;Edwards, Aurelie;Layton, Anita T.
Chen J，Edwards A，莱顿AT. pH和延髓血流量对大鼠外延髓氧转运和钠重吸收的影响。美国肾脏生理学杂志298：F1369-F1383，2010年。首次发表于2010年3月24日; doi：10.1152/ajprenal.00572.2009。我们使用了一个数学模型的O-2运输和尿浓缩机制的外髓质的大鼠肾脏的血液pH值和髓质血流量对O-2的可用性和Na+重吸收的影响进行了研究。该模型预测，在体内的细胞旁Na+通量在髓厚升支（mTAL）是小的相对于跨细胞Na+通量和细胞旁通量有利于Na+重吸收从管腔沿着大多数mTAL段。此外，模型结果表明，血液pH值有一个显着的影响O-2运输和Na+重吸收由于玻尔效应，根据较低的pH值降低了O-2的血红蛋白的结合亲和力。因此，我们的模型预测，假定更大的酸度的血液中的束间区域，mTAL的位置，相对于在血管束，有利于提供O-2，以支持高代谢的mTAL的要求，并提高外髓质的浓缩能力。模型结果还表明，血管和肾小管流速的增加导致活性O-2消耗和mTAL活性Na+转运的不成比例的较小增加，尽管O-2和Na+的输送较高。也就是说，在足够高的髓质O-2供应，O-2的需求在外部髓质不精确地调整O-2输送的变化。
Chen J, Edwards A, Layton AT. Effects of pH and medullary blood flow on oxygen transport and sodium reabsorption in the rat outer medulla. Am J Physiol Renal Physiol 298: F1369-F1383, 2010. First published March 24, 2010; doi: 10.1152/ajprenal.00572.2009.-We used a mathematical model of O-2 transport and the urine concentrating mechanism of the outer medulla of the rat kidney to study the effects of blood pH and medullary blood flow on O-2 availability and Na+ reabsorption. The model predicts that in vivo paracellular Na+ fluxes across medullary thick ascending limbs (mTALs) are small relative to transcellular Na+ fluxes and that paracellular fluxes favor Na+ reabsorption from the lumen along most of the mTAL segments. In addition, model results suggest that blood pH has a significant impact on O-2 transport and Na+ reabsorption owing to the Bohr effect, according to which a lower pH reduces the binding affinity of hemoglobin for O-2. Thus our model predicts that the presumed greater acidity of blood in the interbundle regions, where mTALs are located, relative to that in the vascular bundles, facilitates the delivery of O-2 to support the high metabolic requirements of the mTALs and raises the concentrating capability of the outer medulla. Model results also suggest that increases in vascular and tubular flow rates result in disproportional, smaller increases in active O-2 consumption and mTAL active Na+ transport, despite the higher delivery of O-2 and Na+. That is, at a sufficiently high medullary O-2 supply, O-2 demand in the outer medulla does not adjust precisely to changes in O-2 delivery.