PMID: 7527620Dec 1, 1994Paper

Effects of isoflurane on ouabain toxicity in canine Purkinje fibers. Comparison with halothane

Anesthesiology
J D Gallagher

Abstract

Although halothane reduces digitalis toxicity, other anesthetics, notably cyclopropane, increase toxicity. This study determined the effects of isoflurane on digitalis toxicity in isolated cardiac tissue and compared these effects with those of halothane. Standard microelectrode techniques were used to record action potentials from excised canine Purkinje fibers. Fibers were paced at cycle lengths between 1,000 and 250 ms for 20 beats to induce delayed afterdepolarizations, which are membrane potential oscillations indicative of intracellular Na+ and Ca2+ overload, produced in these experiments by digitalis toxicity. The digitalis glycoside ouabain, 2 x 10(-7) M, was added to the Tyrode's solution superfusate to induce delayed after-depolarizations. Action potential variables and the coupling interval and amplitude of afterdepolarizations were then measured. Isoflurane (0.5%, 1%, or 2%) was added with a calibrated vaporizer (n = 8). In a second set of experiments (n = 10), isoflurane 1.25% or halothane 0.75% was added to the superfusate. After measurements had been made, the other agent was substituted. Ouabain produced primary and secondary delayed afterdepolarizations, which were reduced in amplitude by isoflurane in a dose-r...Continue Reading

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