THE ACTION OF THE PSYCHOACTIVE DRUG 2C-B ON ISOLATED RAT THORACIC AORTA

1. 2C-B [2-(4-bromo-2,5-dimethoxyphenyl)ethylamine] elicits concentration-dependent contraction of the mt thoracic aorta (apparent pD2 = 4.55). The maximal contraction (E(max)) attained with 2C-B is less than that produced by either norepinephrine (NE) or serotonin (5-HT). 2. Pretreatment with either prazosin (5 x 10(-9)-10(-8)M) or ketanserin (5 x 10(-9)-10(-8)M) leads to decreased slopes and E(max) in the 2C-B dose-response curves. 3. 2.82 x 10(-5)M 2C-B potentiates the response to low concentrations of NE; 5 x 10(-5)M 2C-B shows similar behaviour, but with reduced E(max). At 10(-6) M 2C-B acts as a competitive 5-HT antagonist; at 2.8 x 10(-5) M, however, it behaves like a non-competitive 5-HT antagonist. 4. Removal of the endothelial lining from the aortal rings only shifts the 2C-B dose-response curve to the left. 5. These results suggest that 2C-B behaves as a partial agonist toward both alpha1-adrenergic and 5-HT2 serotonergic receptors. The endothelium only seems to act as a diffusional barrier to the drug.