Purkinje fibres play an important role in cardiac conduction and have been implicated in arrhythmia in presence of diseased states, genetic mutations, or adverse side effects of drugs. For these reasons, the Purkinje assay is commonly used in pre-clinical in vitro drug assessment of arrhythmic risk. Several investigators have pointed out that rabbit Purkinje cells, compared to other species, have a better sensitivity in detecting arrhythmic risk.