Roberts E L, Feng Z C
Department of Neurology, University of Miami School of Medicine, FL 33136, USA.
Brain Res. 1996 Feb 5;708(1-2):16-20. doi: 10.1016/0006-8993(95)01254-0.
We examined the hypotheses that aging alters the capacity of brain tissue to regulate extracellular K+ activity (K+o), and that age-related decreases in glucose metabolism may underlie these alterations. Hippocampal slices from young adult (6-9 months old), middle-aged (16-19 months old), and aged (26-29 months old) Fischer 344 rats were exposed to physiological solutions containing 5-20 mM glucose maintained at 36-37 degrees C. Schaffer collaterals in each slice were stimulated at 40 Hz for 2 s, and the resulting changes in K+o were recorded with K+o-sensitive microelectrodes placed in stratum pyramidale of hippocampal subfield CA1. We found that K+ clearance from the extracellular space of hippocampal slices was significantly slowed in the middle-aged group compared with the young adult group in physiological solutions containing 5 and 10 mM glucose. Age-related differences in K+o clearance disappeared in 20 mM glucose. Also, the rate of K+o clearance was modified by glucose concentration. These results suggest that K+ transport rates are modified by age, and that age-related alterations in glucose metabolism may be involved.
衰老会改变脑组织调节细胞外钾离子活性（K+o）的能力，且与年龄相关的葡萄糖代谢降低可能是这些改变的基础。将年轻成年（6 - 9个月大）、中年（16 - 19个月大）和老年（26 - 29个月大）的Fischer 344大鼠的海马切片暴露于含5 - 20 mM葡萄糖且维持在36 - 37摄氏度的生理溶液中。对每片海马切片中的Schaffer侧支以40 Hz刺激2 s，并使用置于海马亚区CA1锥体层的K+o敏感微电极记录由此产生的K+o变化。我们发现，在含5 mM和10 mM葡萄糖的生理溶液中，中年组海马切片细胞外空间的钾离子清除速度与年轻成年组相比显著减慢。在20 mM葡萄糖溶液中，与年龄相关的K+o清除差异消失。此外，K+o清除速率受葡萄糖浓度影响。这些结果表明，钾离子转运速率受年龄影响，且可能涉及与年龄相关的葡萄糖代谢改变。
