Miller D L, Olson J C, Parce J W, Owicki J C
Molecular Devices Corporation, Menlo Park, California 94025.
Biophys J. 1993 Mar;64(3):813-23. doi: 10.1016/S0006-3495(93)81442-5.
The activation of a wide range of cellular receptors has been detected previously using a novel instrument, the microphysiometer. In this study microphysiometry was used to monitor the basal and cholinergic-stimulated activity of the Na+/K+ adenosine triphosphatase (ATPase) (the Na+/K+ pump) in the human rhabdomyosarcoma cell line TE671. Manipulations of Na+/K+ ATPase activity with ouabain or removal of extracellular K+ revealed that this ion pump was responsible for 8.8 +/- 0.7% of the total cellular energy utilization by those cells as monitored by the production of acid metabolites. Activation of the pump after a period of inhibition transiently increased the acidification rate above baseline, corresponding to increases in intracellular [Na+] ([Na+]i) occurring while the pump was off. The amplitude of this transient was a function of the total [Na+]i excursion in the absence of pump activity, which in turn depended on the duration of pump inhibition and the Na+ influx rate. Manipulations of the mode of energy metabolism in these cells by changes of the carbon substrate and use of metabolic inhibitors revealed that, unlike some other cells studied, the Na+/K+ ATPase in TE671 cells does not depend on any one mode of metabolism for its adenosine triphosphate source. Stimulation of cholinergic receptors in these cells with carbachol activated the Na+/K+ ATPase via an increase in [Na+]i rather than a direct activation of the ATPase.
此前已使用一种新型仪器——微生理计检测到多种细胞受体的激活情况。在本研究中，微生理测定法用于监测人横纹肌肉瘤细胞系TE671中Na⁺/K⁺ 三磷酸腺苷酶（ATP酶）（Na⁺/K⁺ 泵）的基础活性和胆碱能刺激活性。用哇巴因处理Na⁺/K⁺ ATP酶活性或去除细胞外K⁺ 后发现，通过酸性代谢产物的产生监测，该离子泵占这些细胞总能量利用的8.8±0.7%。在一段时间的抑制后泵的激活会使酸化速率短暂高于基线，这与泵关闭时细胞内[Na⁺]（[Na⁺]i）的增加相对应。这种短暂变化的幅度是泵无活性时[Na⁺]i总变化量的函数，而[Na⁺]i总变化量又取决于泵抑制的持续时间和Na⁺ 流入速率。通过改变碳底物和使用代谢抑制剂来改变这些细胞的能量代谢模式，结果显示，与其他一些研究的细胞不同，TE671细胞中的Na⁺/K⁺ ATP酶的三磷酸腺苷来源不依赖于任何一种代谢模式。用卡巴胆碱刺激这些细胞中的胆碱能受体，通过增加[Na⁺]i而非直接激活ATP酶来激活Na⁺/K⁺ ATP酶。
