title: Alpha-adrenergic responsiveness correlates with epinephrine dose for arrhythmias during halothane anesthesia in dogs.
abstract: The dose of epinephrine required to elicit ventricular arrhythmias during halothane anesthesia may depend on end-organ sensitivity. We determined whether the arrhythmogenic dose for epinephrine (ADE) could be correlated with either alpha- or beta-adrenergic responsiveness. After ADE was determined in 26 dogs anesthetized with 1.2 MAC halothane, an in vivo assessment of adrenergic responsiveness was made. The alpha-adrenergic responsiveness was defined as the dose of phenylephrine required to increase mean arterial pressure by 75% (alpha 75), while the dose of isoproterenol causing a 75% increase in heart rate was a measure of beta-adrenergic responsiveness (beta 75). The correlation coefficients for alpha 75 and beta 75 vs ADE then were determined by multiple linear regression analysis. There was a highly significant correlation with the alpha 75 (F = 9.06; P less than 0.01), while no relationship existed with beta 75 (F = 0.52; P greater than 0.05). Thus the alpha-adrenergic responsiveness in individual patients may be used to predict the threshold for epinephrine-induced arrhythmias during halothane anesthesia.
mesh_terms: D000768:Anesthesia, General; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced* / Q000503:physiopathology; D001794:Blood Pressure / Q000187:drug effects; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000009:adverse effects*; D005260:Female; D006221:Halothane; D006339:Heart Rate / Q000187:drug effects; D006352:Heart Ventricles; D007545:Isoproterenol / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D011943:Receptors, Adrenergic, beta / Q000502:physiology
chemical_list: D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D010656:Phenylephrine; D007545:Isoproterenol; D006221:Halothane; D004837:Epinephrine