Key result
Repeated injections of adrenaline in dogs under 20% cyclopropane anesthesia led to tachyphylaxis to its arrhythmic effects, while higher cyclopropane concentrations showed an independent adrenolytic effect.
Tachyphylaxis to adrenaline arrhythmias may develop under cyclopropane without adrenolytic protection; leaves open relevance to modern anesthetics.
Long-continued maintenance of anaesthesia with cyclopropane has been reported to inhibit the induction of arrhythmias by adrenaline through an "adrenolytic effect". This effect is not observed in dogs in which anaesthesia is maintained with 20% cyclopropane, although a tachyphylaxis to the arrhythmic effect of adrenaline develops with repeated injections of the amine. Tachyphylaxis to the induction of multifocal and fibrillatory ventricular rhythms by adrenaline occurs less readily in the thiopental-treated animal. An "adrenolytic effect", independent of the number of injections of adrenaline, is apparent at higher concentrations of cyclopropane. The latter observation may explain in part the finding that cardiac arrhythmias are demonstrable within a limited range of cyclopropane concentrations.
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MacCannell et al. (1964) studied Cardiac arrhythmias. Cyclopropane anesthesia and adrenaline injections vs. Thiopental anesthesia was evaluated on Induction of cardiac arrhythmias (multifocal and fibrillatory ventricular rhythms). Repeated injections of adrenaline in dogs under 20% cyclopropane anesthesia led to tachyphylaxis to its arrhythmic effects, while higher cyclopropane concentrations showed an independent adrenolytic effect.
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