Active transport of potassium and oxygen consumption in the isolated midgut of Hyalophora cecropia.
Active transport of potassium and oxygen consumption in the isolated midgut of Hyalophora cecropia.
复制标题
天蚕离体中肠中钾和耗氧量的主动运输。
DOI：
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发表时间：
1967
影响因子：
2.8
通讯作者：
K. Zerahn
中科院分区：
文献类型：
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作者：
W. Harvey;J. A. Haskell;K. Zerahn
1.流量测量与42 K显示，在透明蝇cecropia的中肠的90至100%的短路电流进行的主动运输钾从血液侧的内腔。2.当钾转运被强烈抑制时，无论是通过从血液侧扣留钾还是通过在管腔上施加大的正电位，离体肠道的氧摄取几乎保持不变。如果钾转运被可忽略的氧摄取增加所激励，则约40 µ当量。每一个人，都要有一个属于自己的归宿。额外的氧气。这种钾转运与氧摄取的比率在物理学上是不可能的。3.在25° C和15° C的温度下，当中肠两侧都浸有32 mM钾时，钾转运量与总耗氧量的比率约为1.3。在较低的钾浓度下，该比值一定较小，在73.5 mM-K时为2.0，可能接近最大值。4.虽然氧摄取与钾转运无关，但反之则不然。钾转运与氧消耗密切相关。5.钾运输的中肠与钠运输的青蛙皮肤，因为钠运输刺激氧化代谢，而钾运输没有。显然，在这两个系统中，运输与能源供应的耦合是不同的。
1. Flux measurements with 42 K reveal that in the isolated midgut of Hyalophora cecropia 90 to 100 % of the short-circuit current is carried by the active transport of potassium from the blood-side to the lumen. 2. When K-transport is strongly depressed, either by withholding potassium from the blood side or by imposing a large positive potential on the lumen, the oxygen uptake of the isolated gut remains virtually unchanged. If the K-transport were to be energized by the negligible increase in oxygen uptake about 40 µ -equiv. of potassium would have to be transported for every µ -equiv. of extra oxygen taken up. This ratio of K-transport to oxygen uptake is thermodynamically impossible. 3. The ratio of potassium transported to total oxygen consumed when the midgut is bathed with 32 mM potassium on both sides is about 1.3 at temperatures of 25° and 15° C. The ratio must be smaller at lower potassium concentrations and is 2.0 at 73.5 mM-K, which may be approaching the maximum value. 4. Although the oxygen uptake is independent of the K-transport, the reverse is not true. There is a close dependency of K-transport on oxygen consumption. 5. K-transport by the midgut contrasts with Na-transport by the frog skin because Na-transport stimulates oxidative metabolism whereas K-transport does not. Evidently the coupling of transport to energy supply is different in the two systems.