Dose-dependent down-regulation of ß-adrenoceptors by isoproterenol in rat C 6 glioma cells

Abstract

Nano- and micromolar isoproterenol concentrations were compared by studying cyclic AMP, ß-adrenoceptor density and ß 1-adrenoceptor mRNA in rat C 6 glioma cells. 1 μM isoproterenol significantly changed all parameters at 15–30 min. The ß 1-antagonist metoprolol attenuated the response. No effects of nanomolar isoproterenol on these early changes were observed, although the density of ß-adrenoceptors was significantly reduced beginning at 12 h. The results indicate a different process for ß-adrenoceptor desensitization in C 6 cells following physiologically low agonist concentrations.