Brunsting J R, Bennekers J H, Schuil H A, Zijlstra W G
Pflugers Arch. 1979 Sep;381(3):293-5. doi: 10.1007/BF00583263.
In dogs in neurolept-anesthesia the successive administration of alpha- and beta-adrenergic blocking agents and atropine, which should cause the functional equivalent of surgical denervation of the heart, always results in a marked tachycardia. The same is observed in conscious dogs, but not during methoxyflurane anesthesia. Bilateral vagotomy and administration of hexamethonium abolish the tachycardia. These observations demonstrate the presence of a vagally mediated chronotropic effect which becomes manifest when the inhibitory vagal effect is eliminated through blockade of the muscarinic receptors with atropine.
