title: Are the prejunctional histamine receptors on sympathetic nerve terminals in guinea-pig isolated atria activated during anaphylaxis in vitro?
abstract: In isolated atria from sensitized guinea-pigs, antigenic challenge with ovalbumin induces an anaphylactic reaction in which there is an increased rate and force of contraction. At the same time, stimulation-induced release of [3H] noradrenaline is inhibited by 40%. Cimetidine decreased the tachycardia occurring during anaphylaxis but no effect on the inhibition of stimulation-induced transmitter release. It is known that antigenic challenge of sensitized guinea-pig atria release histamine from mast cells; this histamine acts postjunctionally to increase heart rate. However, the inhibition of noradrenergic transmitter release is not due to the stimulation of prejunctional inhibitory histamine receptors.
mesh_terms: D000707:Anaphylaxis / Q000503:physiopathology*; D000818:Animals; D002927:Cimetidine / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D006321:Heart / Q000294:innervation*; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009411:Nerve Endings / Q000378:metabolism; D009638:Norepinephrine / Q000502:physiology; D010047:Ovalbumin / Q000276:immunology; D011968:Receptors, Histamine / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000378:metabolism*
chemical_list: D011968:Receptors, Histamine; D002927:Cimetidine; D010047:Ovalbumin; D009638:Norepinephrine