Development of a cardiac antiarrhythmic screening test utilizing theophylline in the rat.

Cardiac arrhythmias were produced in Sprague-Dawley-derived rats by chloroform challenge. The incidence of cardiac arrhythmias so induced increased with age and as a function of dose after pretreatment with theophylline. The dose-response and time-action parameters of theophylline's predisposing action to chloroform-hypoxia-induced cardiac arrhythmias were determined. This information has been utilized to develop a cardiac antiarrhythmic screening test in unanesthetized rats which is presented in the following paper.