Responses to Fasting and Lipid Infusion of Epinephrine-induced Arrhythmias during Halothane Anesthesia

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Abstract
Sensitivities to epinephrine in fasted and non-fasted rats anesthetized with halothane or pentobarbital were determined. The arrhythmic threshold for epinephrine (the dose which upon injection produced 4 or more premature ventricular contractions) was significantly lower for 12 h (5.5 .+-. 3.2 .mu.g/kg), 24 h (2.2 .+-. 1.3 .mu.g/kg) and 48 h (2.25 .+-. 0.6 .mu.g/kg) fasted rats than for non-fasted rats (10.9 .+-. 3.4 .mu.g/kg) at the same dose of halothane (2.0%). Fasting had no effect on arrhythmic threshold for epinephrine in rats anesthetized with pentobarbital (35 mg/kg). Infusion of 10% fatty acid emulsion significantly lowered arrhythmic threshold for epinephrine of fed rats, while infusion of acetoacetic acid had no effect on arrhythmic threshold. Apparently the combination of fasting and halothane anesthesia rendered the heart more sensitive to epinephrine than halothane anesthesia alone.