[Attempts to characterize dexamethasone receptors present in rat kidney cytosol]

Density gradient centrifugation analysis has been used to study rat kidney receptors for dexamethasone. Density gradients performed with cytosol incubated with 3H-dexamethasone in a Tris 10 mM, EDTA 1.5 mM, glycerol 5%, monothioglycerol 12 mM (pH 7.5) buffer never gave any good evidence of a 85 radioactivity peak probably due to instability of the complex. The stability of the complex for at least 30 h was achieved by homogenizing the tissue and incubating cytosol in a distilled water, glycerol 5% monothioglycerol 12 mM solution. Density gradient centrifugation analysis in this way showed radioactivity peak at the bottom of the tube probably due to the aggregation of the complex. Since this drawback is inherent in the technique it must be concluded that density gradient centrifugation analysis cannot be used to study the dexamethasone-receptor complex of the kidney.