Activitiesin Vitroof Glucocorticoids and Related Steroids on Glucose Uptake by Rat Thymus Cell Suspensions

Relative activities in vitro with respect to inhibition of net glucose uptake by rat thymus cell suspensions have been measured for a number of steroids over the concentration range from 10-2 to 10-3M. With cortisol =1.0, the activities found were as follows: cortisone <0.01; testosterone <0.01; corticosterone =0.4; prednisolone =1.2; 9α-fluoro-prednisolone =17.6. When the absence of metabolic transformations in the thymus cell system is taken into account, these activities are found to be in good agreement with activities in vivo. The results provide direct evidence for a number of inferences that have been made before regarding the role of metabolic transformations and of steroid-target tissue interactions in determining glucocorticoid activities of steroids with 11-keto, 1,2-dehydro and 9α-fluoro groups. (Endocrinology79: 387, 1966)