豚鼠结肠带平滑肌中28镁与钙和钾的相互作用。

Interaction of 28Mg with Ca and K in the smooth muscle of guinea-pig taenia coli.

Sparrow M P

J Physiol. 1969 Nov;205(1):19-38. doi: 10.1113/jphysiol.1969.sp008948.

Abstract

The uptake of (28)Mg, and the total tissue content of Mg, Ca, Na and K have been determined in the smooth muscle of the guinea-pig taenia coli. The Mg content was 6.56 m-mole/kg fresh wt. immediately after dissection, falling slowly to 5.11 after 6 hr immersion in Krebs solution at 37 degrees C.2. The Mg content rose to 15.4 m-mole/kg fresh wt. during immersion in isotonic sucrose containing only MgCl(2). It was independent of the Mg(2+) concentration in this solution, but was depressed when K(+) or Ca(2+) ions were added.3. (28)Mg uptake showed three separate phases, extracellular, intermediate and slow. The size of the extracellular phase was proportional to the Mg(2+) concentration in the solution, but the size of the slow phase was constant. The size of the intermediate phase, exchanging with a half-time of a few minutes, was depressed when K(+) or Ca(2+) ions were added.4. The results are compatible with a competition between Mg in the intermediate phase of tracer exchange, and K(+) or Ca(2+) ions for fixed anionic sites in the tissue.

摘要

已测定豚鼠结肠带平滑肌中（28）镁的摄取量以及镁、钙、钠和钾的组织总含量。刚解剖后镁含量为6.56毫摩尔/千克鲜重，在37℃的克雷布斯溶液中浸泡6小时后缓慢降至5.11。
在仅含氯化镁的等渗蔗糖溶液浸泡过程中，镁含量升至15.4毫摩尔/千克鲜重。它与该溶液中镁离子浓度无关，但当加入钾离子或钙离子时会降低。
（28）镁的摄取呈现三个不同阶段，即细胞外阶段、中间阶段和缓慢阶段。细胞外阶段的大小与溶液中镁离子浓度成正比，但缓慢阶段的大小恒定。中间阶段以几分钟的半衰期进行交换，当加入钾离子或钙离子时其大小会降低。
这些结果与示踪剂交换中间阶段的镁与钾离子或钙离子在组织中争夺固定阴离子位点的竞争情况相符。