[Activation of glucocorticoid cytoreceptors in rat heart]

Accumulation of 3H-dexamethasone by the nuclei in a cell-free system was studied. The increase in temperature from 0 degrees to 20 degrees C and treatment of cytosol by KCl (0.4 M) or theophylline (10mM) significantly increased the absorption the bound hormone by the nuclear fraction. Activation of the steroid-protein complex induced by temperature and addition of theophylline did not change its size. The increase in the ionic strength decreased the Stokes radius from 53 A down to 39.5 A and the sedimentation coefficient value from 7S down to 4S. It is concluded that the heart tissue cytoplasm contains a glucocorticoid receptor.