Haupert G T, Carilli C T, Cantley L C
Am J Physiol. 1984 Dec;247(6 Pt 2):F919-24. doi: 10.1152/ajprenal.1984.247.6.F919.
Bovine hypothalamus contains a stable, low molecular weight substance with ouabain-like properties. To further study its mechanism of action and potential physiological importance we examined its effects on purified Na+-K+-ATPase in a kinetic coupled-enzyme assay. Under optimal conditions up to 95% of Na+-K+-ATPase activity could be inhibited by the factor. Mg2+ is required for maximal inhibitory activity, but ligand requirements for optimal activity are otherwise distinct from those of both ouabain and vanadate. Inhibition is reversed by high concentrations of sodium chloride plus EDTA. Kinetic analysis yielded a Ki = 1.4 nM. The hypothalamic factor is a high-affinity reversible inhibitor of Na+-K+-ATPase, being at least as potent as the cardiac glycoside ouabain and may be a circulating inhibitor of sodium transport, which appears to be associated with experimental volume-expanded hypertension and human essential hypertension.
牛下丘脑含有一种具有哇巴因样特性的稳定的低分子量物质。为了进一步研究其作用机制和潜在的生理重要性，我们在动力学偶联酶测定中检测了它对纯化的Na⁺-K⁺-ATP酶的影响。在最佳条件下，该因子可抑制高达95%的Na⁺-K⁺-ATP酶活性。最大抑制活性需要Mg²⁺，但最佳活性的配体需求在其他方面与哇巴因和钒酸盐不同。高浓度的氯化钠加EDTA可逆转抑制作用。动力学分析得出Ki = 1.4 nM。下丘脑因子是Na⁺-K⁺-ATP酶的一种高亲和力可逆抑制剂，其效力至少与强心苷哇巴因相当，可能是钠转运的循环抑制剂，这似乎与实验性容量扩张性高血压和人类原发性高血压有关。
