Zager G, Burtis W J, Luetscher J A, Dowdy A J, Sood S
J Clin Endocrinol Metab. 1976 Feb;42(2):207-14. doi: 10.1210/jcem-42-2-207.
During ACTH or cortisol infusion in ten recumbent normal men taking dexamethasone, the metabolic clearance rate of aldosterone increased by 50% as plasma cortisol was raised from low (2 mug/dl) to high concentration (50 mug/dl). Since splanchnic blood flow did not change, a greater efficiency of removal of aldosterone must have occurred, by means of displacement of aldosterone from high-affinity sites on plasma protein. At 37 C, equilibrium dialysis of low-cortisol plasma showed one-third of plasma aldosterone bound to albumin, and 24 to 28% bound to higher-affinity sites on other protein. As plasma cortisol increased, a progressively smaller fraction was tightly bound, approaching zero as transcortin was saturated with cortisol. The addition of large amounts of aldosterone to low-cortisol plasma displaced 14C-cortisol from transcortin binding sites. The results support earlier evidence that a significant fraction of plasma aldosterone is bound to transcortin, from which it is readily displaced by cortisol, resulting in an increased metabolic clearance rate of aldosterone by making a larger fraction available for removal from plasma.
在给十名正在服用地塞米松的仰卧位正常男性输注促肾上腺皮质激素（ACTH）或皮质醇期间，随着血浆皮质醇浓度从低水平（2微克/分升）升至高水平（50微克/分升），醛固酮的代谢清除率增加了50%。由于内脏血流量未发生变化，醛固酮的清除效率必然更高，这是通过醛固酮从血浆蛋白上的高亲和力位点被置换实现的。在37℃时，低皮质醇血浆的平衡透析显示，三分之一的血浆醛固酮与白蛋白结合，24%至28%与其他蛋白上的高亲和力位点结合。随着血浆皮质醇增加，紧密结合的部分逐渐减少，当皮质素结合球蛋白被皮质醇饱和时接近零。向低皮质醇血浆中加入大量醛固酮会使14C-皮质醇从皮质素结合位点被置换出来。这些结果支持了早期的证据，即相当一部分血浆醛固酮与皮质素结合球蛋白结合，皮质醇很容易将其从该蛋白上置换下来，通过使更大比例的醛固酮可用于从血浆中清除，从而导致醛固酮的代谢清除率增加。
