Evaluation of chloride/bicarbonate. Exchange in the human colon in vivo.
Evaluation of chloride/bicarbonate. Exchange in the human colon in vivo.
复制标题
氯化物/碳酸氢盐的评估。
DOI：
10.1172/jci110760
复制
发表时间：
1983
期刊：
影响因子：
--
通讯作者：
Fordtran,JS
中科院分区：
文献类型：
--
作者：
Davis,GR;Morawski,SG;SantaAna,CA;Fordtran,JS
在血浆样溶液灌流过程中，氯化物的结肠吸收速率远高于碳酸氢盐的分泌速率(分别为34meq/h和3.5meq/h)。这可能表明阴离子交换(Cl/HCO3)只占总氯离子吸收的一小部分。然而，如果结肠吸收和分泌碳酸氢盐，这种推理将低估阴离子交换的大小。为了了解结肠是否吸收碳酸氢盐，我们灌流了无氯溶液(这将通过(Cl/HCO3交换)消除碳酸氢盐的分泌)，发现结肠以5.1meq/h的速度吸收碳酸氢盐。电化学梯度的计算和腔液PCO2的测量表明，这种碳酸氢盐的吸收是通过电梯度的被动调节的，而不是通过反向的氯/HCO3交换或酸分泌。类血浆和无氯灌流实验的综合结果表明，Cl/HCO3交换速率为8.6meq/h(两个实验中观察到的碳酸氢盐运动之和，分别为3.5meq/h和5.1meq/h)。为了在不同的实验条件下获得二次估计，灌流氯化胆碱-胆碱重碳酸盐(无钠)溶液，用该溶液应消除或显著减少依赖于主动钠转运的氯和重碳酸盐的吸收，并揭示氯/碳酸氢交换的大小。本实验提出的Cl/HCO3交换速率为9.3meq/h，与第一次估算的结果相似。由于在等离子体状溶液的灌流过程中，氯以34meq/h的速率被吸收，氯/HCO3交换约占总氯吸收的四分之一。
During perfusion of a plasma-like solution, colonic absorption rate of chloride was much higher than the secretion rate of bicarbonate (34 vs. 3.5 meq/h, respectively). This might suggest that anion exchange (Cl/HCO3) accounts for only a small fraction of total chloride absorption. However, if the colon absorbs as well as secretes bicarbonate, this reasoning would underestimate the magnitude of the anion exchange. To see if the colon absorbs bicarbonate, we perfused a chloride-free solution (which would eliminate bicarbonate secretion via (Cl/HCO3 exchange) and found that the colon absorbed bicarbonate at a rate of 5.1 meq/h. Calculation of electrochemical gradients and measurement of luminal fluid PCO2 indicated that this bicarbonate absorption was mediated passively in response to electrical gradients, rather than via reversed Cl/HCO3 exchange or acid secretion. The combined results of the plasma-like and chloride-free perfusion experiments suggest Cl/HCO3 exchange at a rate of 8.6 meq/h (the sum of bicarbonate movements, 3.5 and 5.1 meq/h, observed in the two experiments). To obtain a second estimate under different experimental conditions, a choline chloride-choline bicarbonate (sodium-free) solution was perfused; with this solution, chloride and bicarbonate absorption dependent on active sodium transport should be eliminated or markedly reduced, and the magnitude of Cl/HCO3 exchange should be revealed. This experiment suggested a Cl/HCO3 exchange rate of 9.3 meq/h, similar to the first estimate. As chloride was absorbed at a rate of 34 meq/h during perfusion of the plasma-like solution, the Cl/HCO3 exchange provides for approximately one-fourth of total chloride absorption.
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