Finn A L, Rockoff M L
J Gen Physiol. 1971 Mar;57(3):326-48. doi: 10.1085/jgp.57.3.326.
A compartmental model of toad bladder sodium content has been developed, whereby it is possible to measure the four unidirectional fluxes across the opposite faces of the transport compartment, as well as the amount of sodium in the compartment. (24)Na is added to the mucosal medium of a short-circuited bladder mounted between halves of a chamber in which the fluid is stirred by rotating impellers. After a steady state is reached, nonradioactive medium is flushed through both sides of the chamber, collected, and counted. The data from each chamber are fitted to sums of exponentials and interpreted in terms of conventional compartmental analysis. Three exponentials are required, with half-times of 0.2, 2.2, and 14.0 min. It is shown that the first of these represents chamber washout, the second the transport pool, and the third a tissue compartment which is not involved in active sodium transport and which does not communicate with the transport pool. The second compartment contains 10.5 microEq of sodium per 100 mg dry weight, an amount equal to approximately 30% of total tissue sodium. The results also indicate, as expected from electrophysiological data, that the mucosal-facing side of the transport compartment is over 10 times as permeable to sodium as the serosal, or pump, side.
已建立蟾蜍膀胱钠含量的房室模型，据此可以测量跨转运房室相对面的四种单向通量以及房室内的钠含量。将（24）Na添加到安装在腔室两半之间的短路膀胱的粘膜介质中，该腔室中的液体由旋转叶轮搅拌。达到稳态后，用非放射性介质冲洗腔室两侧，收集并计数。每个腔室的数据拟合成指数和，并根据传统的房室分析进行解释。需要三个指数，半衰期分别为0.2、2.2和14.0分钟。结果表明，其中第一个代表腔室冲洗，第二个代表转运池，第三个代表不参与主动钠转运且不与转运池相通的组织房室。第二个房室每100毫克干重含有10.5微当量的钠，该量约占总组织钠的30%。结果还表明，正如从电生理数据所预期的那样，转运房室面向粘膜的一侧对钠的通透性比浆膜侧（即泵侧）高10倍以上。
