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

Abstract

1. 2C-B [2-(4-bromo-2,5-dimethoxyphenyl)ethylamine] elicits concentration-dependent contraetion of the rat thoracic aorta (apparent pD2 = 4.55). The maximal contraction (Emax) attained wíth 2C-B is less than that produced by either norepinephrine (NE) or serotonin (5-HT). 2. Pretreatment wíth either prazosin (5 x 10-9-10-8 M) or ketanserin (5 x 10-9_10-8 M) leads to decreased slopes and Emax in the 2C-B dose-response curves. 3. 2.82 x 10-5M 2C-B potentiates the response to low concentrations of NE; 5 x 10-5M 2C-B shows similar behaviour, but wíth reduced Emax• 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 endotheliallining from the aortal rings on1y shifts the 2C-B dose-response curve to the left. 5. These results suggest that 2C-B behaves as a partial agonist toward both cxl-adrenergíc and 5-HT2 serotonergíc receptors. The endothelium only seems to act as a diffusional barrier to the drug.