Role of topology in bioenergetics of sodium transport in complex epithelia.
Role of topology in bioenergetics of sodium transport in complex epithelia.
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拓扑结构在复杂上皮细胞钠转运生物能学中的作用。
DOI：
10.1152/ajprenal.1986.250.6.f1107
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
Mikulecky,DC
中科院分区：
文献类型：
--
作者：
Huf,EG;Mikulecky,DC
关于钠转运上皮细胞中是否存在一些争议（例如，蛙皮、蟾蜍膀胱）的Na-O 2比与钠跨上皮转运的净速率无关或在很宽的转运速率范围内保持恒定。这一计算机模拟研究表明，这两种观点都是站得住脚的，这取决于人们是否希望在计算中排除或包括“静压头”能量。这种能量来自膜内钠再循环，如图所示，当应用多室上皮膜模型时。假设合理的动力学参数的传输模型，其钠的传输速率是在一个很宽的范围内变化的逐步模拟阿米洛利的行动，计算表明如下。当从计算中排除静压头能量（O2消耗）时，Na-O2比在跨上皮钠通量的宽范围内是恒定的，高达20 neq X cm-2 X min-1的测试值，这是在青蛙皮肤中发现的“正常”值。在低钠和高钠模型中，Na-O2比值分别为19.4和28.7。如果计算中包括静压头能量，则Na-O2比随着从零值到高达15.7的值的运输速率的增加而增加。这些数据与实验室的结果是一致的，因为是派生的唯象系数和热力学耦合系数的数据（LNa = 80，128; LNa，r = 4.4; Lr = 0.27，0.58; q = 0.50，0.90，取决于所选择的模型参数）。
There has been some controversy as to whether in sodium-transporting epithelia (e.g., frog skin, toad urinary bladder) the Na-O2 ratio is independent of the net rate of transepithelial sodium transport or remains constant over a wide range of transport rates. This computer simulation study shows that both views are defensible, depending on whether one wishes to exclude or include “static head” energy in the calculations. This energy arises from intramembrane sodium recirculation, as shown here when applying a multicompartment epithelial membrane model. Assuming reasonable kinetic parameters of a transport model whose sodium transport rate is varied over a wide range by a step-by-step simulated amiloride action, the computations have shown the following. When static head energy (O2 consumption) is excluded from the calculations, the Na-O2 ratio is constant over a wide range of transepithelial sodium flux, up to the tested value of 20 neq X cm-2 X min-1, a “normal” value found in frog skin. The Na-O2 ratios were 19.4 and 28.7 in low- and high-sodium models, respectively. If the static head energy is included in the calculations, the Na-O2 ratios increase with increasing transport rate from zero values to values up to 15.7. These data are in good agreement with laboratory results, as are derived data on phenomenological coefficients and thermodynamic coupling coefficients (LNa = 80, 128; LNa,r = 4.4; Lr = 0.27, 0.58; q = 0.50, 0.90, depending on the chosen model parameters).