Instrumentation of the awake unrestrained rat for ECG and respiration

Our goal was to record electrocardiogram (ECG) and respiration data from an awake, freely moving rat. The technique presented here requires simple surgery in which two electrodes and a ground wire are placed subcutaneously across the chest, which is externalized via a connector on the top of the subjects head. From these leads it is possible to collect ECG in a standard two lead configuration, and respiration with impedance pneumography. Utilizing electrode placement and signal filtering we were able to obtain ECG from anaesthetized, and awake rats without the effects of motion artifact. Respiration was collected with little effect of motion in all but one subject which displayed excessive movement.