title: Corynanthine inhibits, while idazoxan potentiates, cardiotoxic effects of ouabain.
abstract: 1. Ouabain, infused intravenously to anaesthetized guinea-pigs induced ventricular premature beats, ventricular tachyarrhythmias and lethality. 2. Corynanthine (1, 2 and 4 mg kg-1), an alpha 1-adrenoceptor antagonist and idazoxan (100, 200 and 400 micrograms kg-1), an alpha 2-adrenoceptor antagonist were administered 10 min prior to ouabain. Corynanthine (2 and 4 micrograms kg-1) showed significant increase in the amount of ouabain required to cause arrhythmia and lethality, whereas idazoxan (200 and 400 micrograms kg-1) decreased it. 3. Corynanthine inhibited the ouabain-induced pressor response while idazoxan potentiated it. 4. Effects of these agents on the sympathetic nervous system appear to have played a significant role in its anti- and proarrhythmic actions.
authors.affiliation: Department of Pharmacology, IDPL Research Centre, Hyderabad, India.
authors.forename: G P
authors.initials: GP
authors.lastname: Thomas
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced* / Q000503:physiopathology; D001794:Blood Pressure / Q000187:drug effects; D004146:Dioxanes / Q000494:pharmacology*; D004347:Drug Interactions; D005260:Female; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects; D006352:Heart Ventricles / Q000503:physiopathology; D006439:Hemodynamics / Q000187:drug effects; D019329:Idazoxan; D008297:Male; D010042:Ouabain / Q000037:antagonists & inhibitors / Q000633:toxicity*; D015016:Yohimbine / Q000494:pharmacology*
chemical_list: D000317:Adrenergic alpha-Antagonists; D004146:Dioxanes; D015016:Yohimbine; D010042:Ouabain; D019329:Idazoxan