Mouse ECG Acquisition and Isoproterenol Stimulation

Mouse surface electrocardiogram (ECG) tracings were acquired as described^{48 (link)}. Prior to the ECG acquisition 6–8 week female and male mice were pre-anesthetized with 2% isoflurane in 1l oxygen/min (Isotec100 Series, Isoflurane Vaporizer, Harvard Apparatus, Holliston, USA). Mice were placed in a supine position on a heated ECG pad (Mousepad, THM 100, Indus Intruments, Webster, USA), and the limbs were attached to the pad electrodes using a tape to obtain ECG lead II. Anesthesia was maintained via facemask by continuous isoflurane ventilation as described above. The body temperature was continuously monitored using a rectal probe and sustained within 36–37°C. To obtain a baseline ECG, animals were allowed to rest for 5 min after being positioned on the pad. Thereafter Isoproterenol (10 μg/kg) was injected i.p. ECG acquisition was performed continuously using a multichannel amplifier and data acquisition system (Powerlab 16/30, AD Instruments, Colorado Springs, USA) converting the signal into digital for a further data analysis (Labchart Pro software, version 7, AD Instruments, Colorado Springs, USA).