A simple method for recording electrocardiograms in conscious, unrestrained rats

Electrocardiogram recording gives much information about cardiac activity and is often required for pharmacological studies. To obtain long-term recordings from laboratory rodents, with neither anesthesia nor stress for the animals, a simple technique was developed. Electrodes were implanted in rats subcutaneously 2 days before experiments. Electrocardiograms could then be recorded for several days without disturbing the rats. Signal quality allowed detection of arrhythmias. The effects of the administration of an organophosphorus compound are presented.