A mathematical model of O2 transport in the rat outer medulla. II. Impact of outer medullary architecture
A mathematical model of O2 transport in the rat outer medulla. II. Impact of outer medullary architecture
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DOI：
10.1152/ajprenal.90497.2008
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发表时间：
2009-08-01
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.
陈杰，edward A, Layton AT。大鼠外髓质O-2转运的数学模型。2。外髓结构的影响。[J] .中国生物医学工程学报，2009,31(5):537- 548。首次发表于2009年4月29日；doi: 10.1152 / ajprenal.90497.2008。在伴随研究中（Am J Physiol肾生理学）。首次发表于2009年4月29日；doi: 10.1152/ajprenal.90496.2008)，我们扩展了Layton和Layton （Am J Physiol Renal Physiol 289: F1346-F1366, 2005）开发的基于区域的大鼠外髓质（OM）尿浓缩机制的数学模型，以研究OM复杂的结构组织对O-2运输和分布的影响。在本研究中，我们研究了预测PO2剖面对几个参数的敏感性，这些参数表征了OM区域化程度、边界条件、结构尺寸、跨壁运输性质以及小管和血管的相对位置和分布。我们的研究结果表明，由于长段直血管在维管束中被隔离，提供给直血管降血管（DVR）到达内髓质的O-2的比例，即OM中轴向PO2梯度的测量，对参数变化不敏感。相比之下，血管核心周围区域的O-2分布强烈依赖于髓质厚升肢相对于血管核心的径向位置、区区化程度和短DVR沿皮质-髓轴的分布。此外，如果假设当金属tal PO2低于临界水平时，金属tal活性Na+输运率降低，则金属tal的O-2可用性对模型OM的浓缩能力有显著影响。该模型还预测，当心肌肥大时，其浓缩能力只有在无氧代谢支持相当部分的金属离子活性Na+运输时才会显著增加，否则，在肥大的心肌中，由于间质和金属离子腔内PO2的降低，其浓缩能力会严重降低。
Chen J, Edwards A, Layton AT. A mathematical model of O-2 transport in the rat outer medulla. II. Impact of outer medullary architecture. Am J Physiol Renal Physiol 297: F537-F548, 2009. First published April 29, 2009; doi:10.1152/ajprenal.90497.2008.-In the companion study (Am J Physiol Renal Physiol. First published April 29, 2009; doi: 10.1152/ajprenal.90496.2008), we extended the region-based mathematical model of the urine-concentrating mechanism in the rat outer medulla (OM) developed by Layton and Layton (Am J Physiol Renal Physiol 289: F1346-F1366, 2005) to examine the impact of the complex structural organization of the OM on O-2 transport and distribution. In the present study, we investigated the sensitivity of predicted PO2 profiles to several parameters that characterize the degree of OM regionalization, boundary conditions, structural dimensions, transmural transport properties, and relative positions and distributions of tubules and vessels. Our results suggest that the fraction of O-2 supplied to descending vasa recta (DVR) that reaches the inner medulla, i.e., a measure of the axial PO2 gradient in the OM, is insensitive to parameter variations as a result of the sequestration of long DVR in the vascular bundles. In contrast, O-2 distribution among the regions surrounding the vascular core strongly depends on the radial positions of medullary thick ascending limbs (mTALs) relative to the vascular core, the degree of regionalization, and the distribution of short DVR along the corticomedullary axis. Moreover, if it is assumed that the mTAL active Na+ transport rate decreases when mTAL PO2 falls below a critical level, O-2 availability to mTALs has a significant impact on the concentrating capability of the model OM. The model also predicts that when the OM undergoes hypertrophy, its concentrating capability increases significantly only when anaerobic metabolism supports a substantial fraction of the mTAL active Na+ transport and is otherwise critically reduced by low interstitial and mTAL luminal PO2 in a hypertrophied OM.