Key result
Corynanthine significantly increased the amount of ouabain required to cause arrhythmia and lethality in guinea-pigs, whereas idazoxan decreased it.
Why the study?
Does corynanthine or idazoxan alter ouabain-induced cardiotoxicity in anaesthetized guinea-pigs?
Does corynanthine or idazoxan alter ouabain-induced cardiotoxicity in anaesthetized guinea-pigs?
Answers are grounded in this paper and cite their sources.
Alpha 1-adrenoceptor antagonism with corynanthine protects against ouabain-induced cardiotoxicity, while alpha 2-adrenoceptor antagonism with idazoxan exacerbates it, highlighting the role of the sympathetic nervous system in ouabain arrhythmogenesis.
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.
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George Thomas (1995) studied Ouabain-induced cardiotoxicity. Corynanthine and idazoxan vs. Ouabain alone was evaluated on Amount of ouabain required to cause arrhythmia and lethality. Corynanthine significantly increased the amount of ouabain required to cause arrhythmia and lethality in guinea-pigs, whereas idazoxan decreased it.
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