BINDING OF CORTISOL, FLUOCORTOLONE AND DIFLUOROCORTOLONE TO HUMAN-PLASMA PROTEINS

  • 1 January 1977
    • journal article
    • research article
    • Vol. 15  (10) , 545-548
Abstract
Binding properties of 3H-cortisol, 3H-fluocortolone and 3H-difluocortolone by human plasma, human albumin, human-.beta.- and .gamma.-globulins were studied by equilibrium dialysis. Cortisol in physiological concentrations (0.4 .mu.mol/l) is 98% bound in human plasma at 25.degree. C, while fluocortolone and difluocortolone are 96% and 85% bound, respectively. Under physiological conditions cortisol is mainly bound to the corticosteroid binding globulin (transcortin). Some 2/3 of fluocortolone is bound to transcortin and 1/3 to albumin and globulins, whereas difluocortolone is mainly bound to albumin and to globulins but not to transcortin. Binding affinities of .beta.- and .gamma.-globulins are very low for corticoids investigated, but they are higher for fluocortolone and difluocortolone than for cortisol.