Arterial glucocorticoid receptors: the binding of tritiated dexamethasone in rabbit aorta

Current concepts of the mechanism of the physiological action of both mineralocorticoids and glucocorticoids include an initial step in interaction between the steroid and specific receptors in the cytoplasm of target tissue cells. Using cells from rabbit aorta as a model system, we have studied the cytoplasmic binding of 3H-dexamethasone and 3H-aldosterone. Aorta cells appear to contain binding sites with a high affinity (Kd 4 degrees C approximately 1.3 X 10(-8) mol) for dexamethasone, and with specificity appropriate for glucocorticoid receptors. Under similar experimental conditions, mineralocorticoid receptors could not be demonstrated.