The effect of hyperthermia on the sodium-potassium pump in Chinese hamster ovary cells.
The effect of hyperthermia on the Na+-K+ pump was determined by measuring influx and efflux of 86Rb+ in Chinese hamster ovary cells from 31 to 50 degrees C. The maximum initial rate of ouabain-sensitive influx increased with temperature between 31 and 45 degrees C although Km increased significantly above 37 degrees C, implying a diminished affinity of the transport protein for its substrate. The changes in the kinetics of influx at temperatures up to 45 degrees C were rapidly reversible on return to 37 degrees C. Above 45 degrees C an irreversible decrease in 86Rb+ uptake was observed. Efflux of 86Rb+ increased from 31 to 40 degrees C but above 43 degrees C showed a small but significant decrease. The study of 86Rb+ influx after varying times of exposure to elevated temperatures showed that the Na+-K+ pump remains functional in cells which are reproductively dead. We have shown that although the kinetics of K+ transport are sensitive to temperature changes in the range used in clinical hyperthermia, the inactivation of the Na+-K+ pump is not a primary event in cell killing.
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Mackillop
D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D006358:Hot Temperature; D066298:In Vitro Techniques; D007473:Ion Channels / Q000378:metabolism*; D010053:Ovary
D007473:Ion Channels