title: Effects of reserpine and 6-hydroxydopamine on the adrenergic and purinergic components of sympathetic nerve responses of the rabbit saphenous artery.
abstract: 1 The effects of reserpine and of 6-hydroxydopamine on the contractions of the rabbit isolated saphenous artery produced by stimulation of the sympathetic nerves were studied. 2 In vessels exposed to reserpine, substantial contractions to nerve stimulation were recorded despite a 95.7% reduction in the noradrenaline content of the tissue. These responses of the vessel were not significantly affected by the alpha 1-antagonist, prazosin, whereas after desensitization of the P2-purinoceptor with alpha, beta-methylene ATP, no response to nerve stimulation remained. 3 In vessels exposed to 6-hydroxydopamine, no nerve-mediated responses were observed. 4 Noradrenaline-containing nerves were observed by fluorescence histochemistry in control tissues, but were not observed in tissues treated with reserpine or 6-hydroxydopamine. 5 The potencies of ATP and histamine were not significantly affected by reserpine or 6-hydroxydopamine treatment. However, there was a slight supersensitivity to noradrenaline in reserpine-treated and 6-hydroxydopamine-treated vessels compared with that of control vessels. Prazosin was selective for alpha-adrenoceptors, while alpha, beta-methylene ATP was selective for P2-purinoceptors. 6 These results substantiate the finding that ATP and noradrenaline are sympathetic cotransmitters in the rabbit isolated saphenous artery, and demonstrate that ATP can act as a transmitter independently of noradrenaline in this vessel.
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology; D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000294:innervation; D005453:Fluorescence; D006651:Histocytochemistry; D006892:Hydroxydopamines / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000294:innervation*; D009638:Norepinephrine / Q000378:metabolism / Q000502:physiology; D016627:Oxidopamine; D011224:Prazosin / Q000494:pharmacology; D011687:Purines / Q000502:physiology*; D011817:Rabbits; D012110:Reserpine / Q000494:pharmacology*; D013564:Sympathetic Nervous System / Q000187:drug effects*
chemical_list: D006892:Hydroxydopamines; D011687:Purines; D012110:Reserpine; D016627:Oxidopamine; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D009638:Norepinephrine; D011224:Prazosin