Mikkelsen R B, Asher C R
Department of Radiation Oncology, New England Medical Center, Boston, Massachusetts 02111.
J Cell Physiol. 1990 Aug;144(2):216-21. doi: 10.1002/jcp.1041440206.
The effects of hyperthermia (41-43 degrees C) on the membrane potential (calculated from the transmembrane distribution of [3H]tetraphenylphosphonium) and Na+ transport of Chinese hamster V79 fibroblasts were studied. At 41 degrees C, hyperthermia induced a membrane hyperpolarization of log phase cells (5 to 26 mV) that was reversible upon returning to 37 degrees C. The hyperpolarization was inhibited 50% by 1 mM ouabain or 0.25 mM amiloride, an inhibitor of Na+:H+ exchange. Shifting temperature to 41 degrees C increased ouabain-sensitive Rb+ uptake indicating activation of the electrogenic Na+ pump. At 43 degrees C for 60 min, the membrane potential of log phase cells depolarized (20-35 mV). Parallel studies demonstrated enhanced Na+ uptake at 41 degrees C only in the presence of ouabain. At 43 degrees C, Na+ uptake was increased relative to controls with or without ouabain present. At both 41 and 43 degrees C, 0.25 mM amiloride inhibited heat-stimulated Na+ uptake. Na+ efflux was enhanced at 41 degrees C in a process inhibited by ouabain. Thus, one consequence of heat treatment at 41 degrees C is activation of Na+:H+ exchange with the resultant increase in cytosolic [Na+] activating the electrogenic Na+ pump. At temperatures greater than or equal to 43 degrees C, the Na+ pump is inhibited.
研究了热疗（41 - 43摄氏度）对中国仓鼠V79成纤维细胞膜电位（由[3H]四苯基鏻的跨膜分布计算得出）和Na +转运的影响。在41摄氏度时，热疗诱导对数期细胞出现膜超极化（5至26毫伏），回到37摄氏度后可逆转。1毫摩尔哇巴因或0.25毫摩尔氨氯吡脒（一种Na +:H +交换抑制剂）可抑制50%的超极化。将温度升至41摄氏度会增加哇巴因敏感的Rb +摄取，表明电生性Na +泵被激活。在43摄氏度处理60分钟时，对数期细胞的膜电位去极化（20 - 35毫伏）。平行研究表明，仅在存在哇巴因的情况下，41摄氏度时Na +摄取增加。在43摄氏度时，无论有无哇巴因，Na +摄取相对于对照组均增加。在41和43摄氏度时，0.25毫摩尔氨氯吡脒均抑制热刺激的Na +摄取。在41摄氏度时，哇巴因抑制的过程中Na +外流增强。因此，41摄氏度热处理的一个结果是激活Na +:H +交换，导致胞质[Na +]增加，进而激活电生性Na +泵。在温度大于或等于43摄氏度时，Na +泵被抑制。
