Inhibitory effects of alpha, beta-methylene ATP on nerve-mediated contractions of the nictitating membrane in reserpinised cats.
Residual responses of the cat nictitating membrane to nerve stimulation were obtained after reserpine pretreatment (40% of controls), in spite of a pronounced reduction in noradrenaline content. The putative ATP-receptor desensitising agent alpha, beta-methylene ATP (alpha, beta-MATP), administered intraarterially through the lingual artery produced a contraction of the nictitating membrane and subsequently inhibited the residual responses evoked by sympathetic nerve stimulation in reserpinised cats. These doses of alpha, beta-MATP did not modify the contractions evoked by exogenous noradrenaline (i.a.) but antagonized the contractions of the nictitating membrane elicited by beta, gamma-methylene ATP, which is an agonist at P2 receptors. These results are compatible with a co-transmitter role for ATP in the neurally mediated contractile responses of the nictitating membrane following depletion of endogenous noradrenaline stores by pretreatment with reserpine.
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002415:Cats; D004558:Electric Stimulation; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009474:Neurons / Q000502:physiology*; D009541:Nictitating Membrane / Q000187:drug effects / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D012110:Reserpine / Q000494:pharmacology; D013564:Sympathetic Nervous System / Q000187:drug effects
C005147:5'-adenylyl (beta,gamma-methylene)diphosphonate; D001285:Atropine; D012110:Reserpine; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D009638:Norepinephrine; D011224:Prazosin