Influence of dopamine and noradrenaline on isolated cerebral arteries of the dog.
1 Effects of dopamine and noradrenaline were compared in helically-cut strips of canine cerebral arteries. 2 Dopamine caused a greater maximal contraction than noradrenaline, although the ED50 for noradrenaline was appreciably less. The contraction induced by these amines was reversed to a relaxation by treatment with phenoxybenzamine. 3 Relaxation induced by dopamine in phenoxybenzamine-treated and prostaglandin-contracted cerebral arteries was not influenced by 1 muM propranolol, while relaxation induced by noradrenaline at low concentrations (2 muM and 10 muM) was significantly attenuated. Neither aminophylline nor atropine affected the relaxant effect of dopamine. 4 A mechanism other than beta-adrenergic, cholinergic or adenosine-related appears to be involved in the relaxation elicited by dopamine in cerebral arterial strips.
D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D002536:Cerebral Arteries / Q000187:drug effects*; D004285:Dogs; D004298:Dopamine / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology*; D010643:Phenoxybenzamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011453:Prostaglandins / Q000494:pharmacology
D011453:Prostaglandins; D010643:Phenoxybenzamine; D011433:Propranolol; D000241:Adenosine; D004298:Dopamine; D009638:Norepinephrine