Balaban R S, Mandel L J, Soltoff S P, Storey J M
Proc Natl Acad Sci U S A. 1980 Jan;77(1):447-51. doi: 10.1073/pnas.77.1.447.
We report the results of studies in which the cytoplasmic coupling between Na+,K+-ATPase activity (presumably a measure of active transport) and the mitochondrial respiratory rate was investigated in a tubule suspension from the rabbit kidney cortex. Simultaneous measurements of the redox state of mitochondrial nicotinamide adenine dinucleotide (NAD) (performed fluorometrically), the cellular ATP and ADP concentrations, and the oxygen consumption rate (QO2) were made under conditions known to alter the Na+,K+-ATPase turnover. Ouabain (25 microM) caused: (i) a 54% inhibition of QO2, (ii) a net reduction of NAD, and (iii) a 30% increase in the ATP/ADP ratio. The addition of K+ (5 ?M) to K+-depleted tubules caused: (i) an initial 127% stimulation of QO2 followed by a new steady-state QO2 50% above control, (ii) an initial large oxidation of NAD followed by a new steady state more oxidized than the control level, and (iii) a 47% decrease in the cellular ATP/ADP ratio. These data indicate that the cellular ATP and ADP concentrations or the ATP/ADP ratio may be part of the coupling mechanism linking Na+,K+-ATPase turnover and the aerobic metabolic rate in kidney.
我们报告了相关研究结果，这些研究对兔肾皮质肾小管悬浮液中Na⁺,K⁺-ATP酶活性（大概是主动转运的一种度量）与线粒体呼吸速率之间的细胞质偶联进行了研究。在已知会改变Na⁺,K⁺-ATP酶周转的条件下，同时测定了线粒体烟酰胺腺嘌呤二核苷酸（NAD）的氧化还原状态（通过荧光法进行）、细胞内ATP和ADP浓度以及耗氧率（QO₂）。哇巴因（25微摩尔）导致：（i）QO₂ 受到54% 的抑制，（ii）NAD净减少，以及（iii）ATP/ADP比值增加30%。向低钾的肾小管中添加K⁺（5微摩尔）导致：（i）QO₂ 最初受到127% 的刺激，随后新的稳态QO₂ 比对照高50%，（ii）NAD最初大量氧化，随后新的稳态比对照水平氧化程度更高，以及（iii）细胞内ATP/ADP比值降低47%。这些数据表明，细胞内ATP和ADP浓度或ATP/ADP比值可能是连接兔肾中Na⁺,K⁺-ATP酶周转与有氧代谢率的偶联机制的一部分。
