Orlov S N, Kolosova I A, Cragoe E J, Gurlo T G, Mongin A A, Aksentsev S L, Konev S V
Laboratory of Physical Chemistry of Biomembranes, School of Biology, Moscow State University, Russia.
Biochim Biophys Acta. 1993 Sep 19;1151(2):186-92. doi: 10.1016/0005-2736(93)90103-7.
The kinetics of the volume-dependent activation of Na+/H+ exchange, Na+,K+,2Cl(-)-cotransport and K+,Cl(-)-cotransport in rat erythrocytes was studied. The significant increase in the rate of Na+/H+ exchange is observed within 15 min after hypertonic shrinkage while the maximum transport rate is reached by 20 min. A delay of about 5 min was found in activation of Na+,K+,2Cl(-)-cotransport, the maximum transport rate being reached 10 min after shrinkage. Activation of K+,Cl(-)-cotransport by hypotonic swelling was registered within 10 min after cell swelling, with a simultaneous achievement of the constant transport rate. Preincubation of cells at 49 degrees C has no effect on the basal Na+/H+ exchange and Na+,K+,2Cl(-)-cotransport but suppresses the activation of these systems by osmotic shrinkage. On the contrary, the rate of K+,Cl(-)-cotransport in isosmotic medium is raised 10-fold after preincubation at 49 degrees C. The thermal treatment at 49 degrees C blocks the activation of K+,Cl(-)-cotransport by swelling. On the basis of the data on thermal denaturation of spectrin at the same temperature it was suggested that the cytoskeleton of erythrocyte membrane is involved in volume regulation of the ion-transporting systems and that the molecular mechanisms which underlie the activation of Na+/H+ exchange, Na+,K+,2Cl(-)-cotransport and K+,Cl(-)-cotransport are essentially different.
研究了大鼠红细胞中钠/氢交换、钠钾氯协同转运和钾氯协同转运的体积依赖性激活动力学。高渗收缩后15分钟内观察到钠/氢交换速率显著增加，而在20分钟时达到最大转运速率。发现钠钾氯协同转运的激活延迟约5分钟，收缩后10分钟达到最大转运速率。低渗肿胀激活钾氯协同转运在细胞肿胀后10分钟内即可记录到，同时达到恒定转运速率。细胞在49℃预孵育对基础钠/氢交换和钠钾氯协同转运没有影响，但抑制了这些系统因渗透收缩而产生的激活。相反，在49℃预孵育后，等渗介质中钾氯协同转运的速率提高了10倍。49℃的热处理阻止了肿胀对钾氯协同转运的激活。基于在相同温度下血影蛋白热变性的数据，有人提出红细胞膜的细胞骨架参与离子转运系统的体积调节，并且钠/氢交换、钠钾氯协同转运和钾氯协同转运激活的分子机制本质上是不同的。
