A Procedure for Measuring Plasma Binding of Adrenal Corticoids;Effect of Acute and Chronic Stress. ∗

Summary

A method is described utilizing zinc sulfate precipitation of plasma proteins which, when used in conjunction with standard fluorometric measurements of corticos-terone and cortisol, will eliminate residual fluorescence and demonstrate apparent differences in the relative amount of unbound and protein-bound corticoids in plasma of rats and guinea pigs subjected to several different physiological situations. Under basal, non-stressed conditions the corticoids are almost entirely protein-bound. Acute stress of ether or pentobarbital anesthesia and chronic stress of cold exposure increase markedly peripheral plasma corticoid levels; the increment in corticoids during acute stress is predominately unbound, while the increment during chronic cold is associated with protein precipitated by zinc sulfate.