Owen A, Caplan S R, Essig A
Biochim Biophys Acta. 1975 Jul 3;394(3):438-48. doi: 10.1016/0005-2736(75)90295-3.
Previous studies support the validity of a linear thermodynamic formalism relating the rates of active Na-+ transport and oxygen consumption Jr to the electrical potential difference delta-psi and the affinity A (negative free energy) of the metabolic driving reaction. The formulation was further tested in paired control and experimental hemiskins by the use of two inhibitors of Na-+ transport. Ouabain, a specific inhibitor of the Na-+ pump, might be expected to diminish the dependence of Jr on delta-psi without affecting A, whereas 2-deoxy-D-glucose, a competitive inhibitor of glucose metabolism should be expected to diminish A. Both inhibitors were used at concentrations adequate to depress Na-+ transport (i.e. short-circuit current Io) to some 50% of control level. Measurements were made of Io and dJr/d(delat-psi), and the apparent value of the affinity Aapp was calculated according to the thermodynamic formulation. Ouabain depressed minus dJr/d(delta-psi) without affecting Aapp whereas 2-deoxy-D-glucose depressed Aapp without affecting minus dJr/d(delta-psi). The demonstration of these effects indicated the utility of the formalism.
先前的研究支持一种线性热力学形式体系的有效性，该体系将主动钠转运速率和氧消耗速率Jr与电势差δψ以及代谢驱动反应的亲和力A（负自由能）联系起来。通过使用两种钠转运抑制剂，在配对的对照和实验性半皮肤中对该公式进行了进一步测试。哇巴因是钠泵的特异性抑制剂，预计它会降低Jr对δψ的依赖性而不影响A，而2-脱氧-D-葡萄糖是葡萄糖代谢的竞争性抑制剂，预计它会降低A。两种抑制剂均以足以将钠转运（即短路电流Io）降低至对照水平约50%的浓度使用。测量了Io和dJr/d(δψ)，并根据热力学公式计算了亲和力Aapp的表观值。哇巴因降低了-dJr/d(δψ)而不影响Aapp，而2-脱氧-D-葡萄糖降低了Aapp而不影响-dJr/d(δψ)。这些效应的证明表明了该形式体系的实用性。
