Binding of testosterone in mouse plasma.

The binding of testosterone (T) in the plasma of adult male mice was examined using florisil absorption. The binding decreased as the temperature of incubation increased, and was substantially reduced by preheating the plasma at 75 degrees C. The addition of an excess of cold T did not displace 3H-T, and the binding did not depend on the concentration of endogenous T in the plasma. It appears that, under physiological conditions, approximately 60% of the T present in the peripheral circulation of male mice is bound to plasma components, probably mostly to albumin.