Evidence against purines being neurotransmitters of non-adrenergic, non-cholinergic nerves in rat duodenum.
The possible involvement of purines in the non-adrenergic non-cholinergic (NANC) relaxation of rat duodenum was studied using an isometric-isovolumic preparation. Purines (adenosine, AMP, ADP, ATP) induced a concentration-dependent, tetrodotoxin (TTX)-insensitive, fall in both endoluminal pressure and isometric tension. The relaxation induced by adenosine and by 2-chloroadenosine was selectively antagonized by 8-phenyltheophylline (1, 10 nM, 0.5 microM) and the ATP-induced relaxation was opposed by alpha, beta-methylene ATP (10 microM) and by reactive blue 2 (10 microM). Electrical field stimulation (EFS) caused TTX-sensitive inhibitory effects similar to those induced by ATP. None of the purinergic antagonists used were capable of affecting the EFS-induced relaxation. Our results indicate that both P1 and P2 purinoreceptors are present in muscle of the rat duodenum and are not involved in the NANC relaxation.
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Dipartimento di Biologia cellulare e dello Sviluppo, Università di Palermo, Italy.
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D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000244:Adenosine Diphosphate / Q000494:pharmacology; D000249:Adenosine Monophosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001341:Autonomic Nervous System / Q000502:physiology*; D004386:Duodenum / Q000294:innervation* / Q000502:physiology; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D018377:Neurotransmitter Agents / Q000502:physiology*; D011687:Purines / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013779:Tetrodotoxin / Q000494:pharmacology; D013806:Theophylline / Q000031:analogs & derivatives / Q000494:pharmacology
D018377:Neurotransmitter Agents; D011687:Purines; D000249:Adenosine Monophosphate; D013779:Tetrodotoxin; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D013806:Theophylline; C028322:8-phenyltheophylline; D000241:Adenosine