Beta-adrenoceptor and post-receptor components show different rates of desensitization to desipramine

Both 3-day and 15-day desipramine treatments (10 mg/kg, once daily) significantly reduced beta 1- but not beta 2-adrenoceptor and isoproterenol-stimulated adenylyl cyclase activities in rat cortical, hippocampal and amygdaloid membrane preparations. In contrast, 15-day but not 3-day desipramine treatment resulted in a significant reduction in NaF-, GppNHp- and forskolin-stimulated adenylyl cyclase activity. The results suggest that post-beta-adrenoceptor component desensitization occurs more slowly than receptor downregulation in response to desipramine.