Inhibition of the activation of the rat liver cytosolic glucocorticoid receptor by Li +

Abstract

By the use of aqueous two-phase partitioning and DNA-Sepharose chromatography, Li + has been found to cause a partial inhibition of the activation of the rat liver glucocorticoid receptor in vitro. During incubations of cytosol with 0.4 M Kcl at 0°C, the LiCl-concentration giving half-maximal effect is approx. 1 mM; at higher temperatures, the receptor is less susceptible to the effect of LiCl. Na + counteracts the effect of Li +, the LiCl-concentration giving half-maximal effect in 0.4 M NaCl being at least 20-fold higher than that in 0.4 M KCl. These findings are best explained by an ion-binding mechanism, Li + and Na + competing for binding, but only the binding of Li + leading to activation inhibition.