Depression of 3H‐Glucose Uptake into Rabbit Polymorphonuclear Leukocytes by Glucocorticoids in Concentrations Partly Saturating the Specific Glucocorticoid Uptake. Evidence for a Glucocorticoid Receptor

Rabbit polymorphonuclear leukocytes have a specific glucocorticoid uptake in vitro, half saturated by cortisol at a probably physiological concentration (about 3 × 10‐9 M). These cells in vitro accumulate 3H‐d‐glucose and 3H‐2‐deoxy‐d‐glucose, possibly by a common uptake step. Cortisol, dexamethasone, 9αF‐prednisolone, prednisolone, triamcinolone and triamcinolone acetonide, all in the low concentrations sufficient to partly saturate the specific glucocorticoid uptake, depress the uptake of 3H‐glucose by these cells. Corticosterone acted as a partial agonist. 11‐epicortisol, tetrahydrocortisone and progesterone, which have no glucocorticoid activity, had a very low activity on 3H‐d‐glucose uptake. For 11‐epicortisol and tetrahydrocortisone this corresponded to a low affinity to the specific glucocorticoid uptake process, while progesterone had a relatively high affinity. Progesterone in high concentrations was shown to block the depressing effect on 3H‐d‐glucose uptake by cortisol, probably by keeping it away from the specific glucocorticoid uptake process. Rabbit polymorphonuclear leukocytes thus seem to have a specific glucocorticoid receptor.