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 rat thoracic aorta (apparent pD2 = 4.55). The maximal contraction (Emax) 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 Emax 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 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 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 alpha 1-adrenergic and 5-HT2 serotonergic receptors. The endothelium only seems to act as a diffusional barrier to the drug.
Lobos
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M
Departamento de Química Farmacológica y Toxicológica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago.
Borges
Y
Y
Gonzalez
E
E
Cassels
B K
BK
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D004118:Dimethoxyphenylethylamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects; D066298:In Vitro Techniques; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011619:Psychotropic Drugs / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D004118:Dimethoxyphenylethylamine; D011619:Psychotropic Drugs; D012701:Serotonin; D007650:Ketanserin; C079321:2-(4-bromo-2,5-dimethoxyphenyl)ethylamine; D009638:Norepinephrine; D011224:Prazosin