Gubitz R H, Akera T, Brody T M
Biochim Biophys Acta. 1977 Feb 7;459(2):263-77. doi: 10.1016/0005-2728(77)90027-5.
The involvement of membrane (Na+ + K+)-ATPase (Mg2+-dependent, (Na+ + K+)-activated ATP phosphohydrolase, E.C. 3.6.1.3) in the oxygen consumption of rat brain cortical slices was studied in order to determine whether (Na+ + K+)-ATPase activity in intact cells can be estimated from oxygen consumption. The stimulation of brain slice respiration with K+ required the simultaneous presence of Na+. Ouabain, a specific inhibitor of (Na+ + K+)-ATPase, significantly inhibited the (Na+ + K+)-stimulation of respiration. These observations suggest that the (Na+ + K+)-stimulation of brain slice respiration is related to ADP production as a result of (Na+ + K+)-ATPase activity. However, ouabain also inhibited non-K+ -stimulated respiration. Additionally, ouabain markedly reduced the stimulation of respiration by 2,4-dinitrophenol in a high (Na+ + K+)-medium. Thus, ouabain depresses brain slice respiration by reducing the availability of ADP through (Na+ + K+)-ATPase inhibition and acts additionally by increasing the intracellular Na+ concentration. These studies indicate that the use of ouabain results in an over-estimation of the respiration related to (Na+ + K+)-ATPase activity. This fraction of the respiration can be estimated more precisely from the difference between slice respiration in high Na+ and K+ media and that in choline, K+ media. Studies were performed with two (Na+ + K+)-ATPase inhibitors to determine whether administration of these agents to intact rats would produce changes in brain respiration and (Na+ + K+)-ATPase activity. The intraperitoneal injection of digitoxin in rats caused an inhibition of brain (Na+ + K+)-ATPase and related respiration, but chlorpromazine failed to alter either (Na+ + K+)-ATPase activity or related respiration.
为了确定完整细胞中的（钠+钾）-ATP酶活性是否可以通过氧消耗来估计，研究了膜（钠+钾）-ATP酶（镁依赖性、（钠+钾）激活的ATP磷酸水解酶，E.C. 3.6.1.3）与大鼠脑皮质切片氧消耗的关系。钾对脑切片呼吸的刺激需要同时存在钠。哇巴因，一种（钠+钾）-ATP酶的特异性抑制剂，显著抑制了（钠+钾）对呼吸的刺激。这些观察结果表明，（钠+钾）对脑切片呼吸的刺激与（钠+钾）-ATP酶活性导致的ADP产生有关。然而，哇巴因也抑制了非钾刺激的呼吸。此外，在高（钠+钾）培养基中，哇巴因显著降低了2,4-二硝基苯酚对呼吸的刺激。因此，哇巴因通过抑制（钠+钾）-ATP酶来减少ADP的可用性，从而降低脑切片呼吸，并且还通过增加细胞内钠浓度起作用。这些研究表明，使用哇巴因会导致对与（钠+钾）-ATP酶活性相关的呼吸的高估。这部分呼吸可以通过高钠和钾培养基中切片呼吸与胆碱、钾培养基中切片呼吸的差异更精确地估计。使用两种（钠+钾）-ATP酶抑制剂进行了研究，以确定将这些药物给予完整大鼠是否会引起脑呼吸和（钠+钾）-ATP酶活性的变化。给大鼠腹腔注射洋地黄毒苷会抑制脑（钠+钾）-ATP酶和相关呼吸，但氯丙嗪未能改变（钠+钾）-ATP酶活性或相关呼吸。
