Increased Corticosteroid Binding ("Transcortin") Activity in Adrenalectomized and Hypophysectomized Rats

Abstract

Equilibrium dialysis experiments with pooled sera of rats demonstrate that the binding activity of the specific corti-costeroid-binding protein ("transcortin") is higher in adrenalectomized and hypophysectomized animals than in normal controls. Rat serum at both 4[degree]C and 37[degree]C has a higher binding affinity for corticosterone than for cortisol, whereas in human serum at 4[degree]C, cortisol appears to be bound more firmly than corticosterone. The "transcortin" systems of man and rat, therefore, show distinct species differences, providing highest binding affinity for the principal corticosteroid of the particular species.