A laboratory animal model for malignant hyperpyrexia.

Strandard laboratory rabbits which are not genetically susceptible to malignant hyperpyrexia were anesthetized with either halothane or pentobarbital. Administration of caffeine in 125 mg increments produced a syndrome strongly resembling malignant hyperpyrexia in rabbits anesthetized with halothane. All these animals became rigid, hyperpyrexic, acidotic and hyperkalemic, whereas caffeine-treated, pentobarbital-anesthetized animals developed only mild acidosis. Pentobarbital alone and halothane alone caused no changes in measured variables. This model for malignant hyperpyrexia resembles the naturally occurring disease more closely than several preceding pharmacologic models.