Dissociation between sympathetic purinergic response and ATP response in the mesenteric artery of the dog.

In the presence of prazosin and propranolol, electrical transmural stimulation of isolated dog mesenteric artery produced a sympathetic purinergic contraction, which was followed by a relaxation in PGF2 alpha-contracted arteries. Such purinergic responses were mimicked by brief exposure to alpha, beta-methylene ATP (alpha, beta-Me ATP) and were completely inhibited after desensitization of P2x-purinergic receptors. However, exogenous ATP predominantly evoked a relaxation in PGF2 alpha-contracted artery. These results suggest that the sympathetic purinergic response may be caused by a P2x-purinergic receptor-selective mechanism or substance, rather than ATP.