title: Effects of alpha,beta-methylene ATP on biphasic responses of rat vas deferens.
abstract: The epididymal region of isolated vas deferens of the rat was stimulated locally with field electrodes. Continuous perfusion with alpha,beta-methylene-adenosine-5'-triphosphate (mATP, 10(-5) M) desensitized the P2-purinoceptors and the effect of this on the two components of tetanic responses and the 'non-adrenergic' and adrenergic phases of single shock responses were examined. Exposure to mATP selectively prevented the contractions to adenosine-5'-triphosphate (ATP, 10(-4)-5 X 10(-4) M) but not noradrenaline (NA, 10(-5) M) and preferentially blocked the secondary but not the primary tetanic component. It also depressed markedly the non-adrenergic phase of single shocks and either reduced or abolished the adrenergic phase. Thus the secondary tension development depends in the rat vas deferens on both the activation of alpha 1-adrenoceptors and the non-adrenergic twitch mechanism. The action of mATP involves more processes than the desensitization of the P2-purinoceptors so does not positively identify purinergic transmission. Direct NA-induced contraction contributes more to the primary than to the secondary tetanic component.
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D004146:Dioxanes / Q000494:pharmacology; D019329:Idazoxan; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D011941:Receptors, Adrenergic / Q000187:drug effects; D011983:Receptors, Purinergic / Q000187:drug effects; D013806:Theophylline / Q000031:analogs & derivatives / Q000494:pharmacology; D014649:Vas Deferens / Q000187:drug effects* / Q000294:innervation
chemical_list: D004146:Dioxanes; D011941:Receptors, Adrenergic; D011983:Receptors, Purinergic; D000255:Adenosine Triphosphate; D013806:Theophylline; C028322:8-phenyltheophylline; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D009638:Norepinephrine; D019329:Idazoxan