Effect of norepinephrine on in vitro histamine release from rat mast cells

The effect of norepinephrine on compound 48/80-induced histamine release from rat peritoneal mast cells, was studied in an in vitro system. It was found that norepinephrine, within the concentration range 10(-5)--10(-3) M, exerts a significant, dose-related, repressive effect. This effect is greatly potentiated by the beta-antagonist practolol (10(-3) M), throughout the concentration range of 10(-11)--10(-3) M norepinephrine. Methoxyamine, a selective alpha-adrenergic agonist, also represses histamine release in a dose-dependent manner; however, it is not as potent as norepinephrine. The present results would seem to suggest that the repressive effect on histamine release, observed within a low concentration range of norepinephrine, may be due to alpha-adrenoceptor mechanisms.