Attenuation of vagal noradrenergic tachycardia by naloxone.
Electrical stimulation of the transected right vagus nerve in anesthetized and atropinized dogs produced tachycardia that was not attenuated by beta-adrenoceptor blockade. Naloxone in intravenous doses of 1 and 4 mg/kg antagonized the tachycardia evoked by nerve stimulation in a dose-dependent manner. However, the attenuation was maximal at approximately 55% of the control response. These results suggest that an endogenous opiate peptide(s) may have a mediator or modulator role in nonadrenergic tachycardia evoked by vagal nerve stimulation in anesthetized and atropinized dogs.
D000262:Adenylyl Cyclases / Q000378:metabolism; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D004285:Dogs; D004558:Electric Stimulation; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D009638:Norepinephrine / Q000502:physiology*; D011433:Propranolol / Q000494:pharmacology; D014630:Vagus Nerve / Q000502:physiology*
D000319:Adrenergic beta-Antagonists; D009270:Naloxone; D001285:Atropine; D011433:Propranolol; D000262:Adenylyl Cyclases; D009638:Norepinephrine