title: Site of adrenaline blockade in the superior cervical ganglion of the rabbit.
abstract: 1. The blocking action of adrenaline on the superior cervical ganglion of the rabbit was investigated with intracellular recording techniques.2. Adrenaline (10(-5)M) blocked initiation of post-synaptic action potentials and decreased the amplitude of excitatory post-synaptic potentials (e.p.s.p.s), but did not hyperpolarize the post-synaptic membrane.3. The depressant action of adrenaline was antagonized by phenoxy-benzamine and dihydroergotamine.4. Acetylcholine depolarizations from iontophoretic ACh were not affected by adrenaline.5. Adrenaline decreased the frequency of miniature excitatory post-synaptic potentials (m.e.p.s.p.s) and decreased the quantal content of e.p.s.p.s in a low [Ca(2+)]: [Mg(2+)] media.6. It was concluded that adrenaline blocks ganglionic transmission by acting at an alpha-adrenoceptive site in the presynaptic nerve terminals.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004837:Epinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004878:Ergotamine / Q000494:pharmacology; D005725:Ganglia, Autonomic / Q000187:drug effects*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009333:Neck; D009411:Nerve Endings; D010643:Phenoxybenzamine / Q000494:pharmacology; D011817:Rabbits; D011955:Receptors, Drug; D013564:Sympathetic Nervous System; D009435:Synaptic Transmission / Q000187:drug effects
chemical_list: D011955:Receptors, Drug; D010643:Phenoxybenzamine; D000109:Acetylcholine; D004878:Ergotamine; D004837:Epinephrine