2918 rodent chow

Animal protocols were approved by the Institutional Animal Care and Use Committee of the Children’s Research Institute and followed the National Institutes of Health’s Guide for the Care and Use of Laboratory Animals. Experiments were conducted using adult, male Sprague-Dawley rats (>8 weeks old, >280 g, Taconic Biosciences). Animals were housed in conventional rat cages in the Research Animal Facility under standard environmental conditions (12:12 hour light:dark cycle, 64°C–78°C, 30%–70% humidity, free access to reverse osmosis water, corn cob bedding, and food [2918 rodent chow; Envigo]). Animals were anesthetized with 3% to 5% isoflurane; the heart was excised and then transferred to a temperature-controlled (37°C) constant-pressure (70 mm Hg) Langendorff perfusion system for electrophysiology and optical mapping experiments. Excised hearts were perfused with Krebs-Henseleit buffer bubbled with carbogen throughout the duration of the experiment, as previously described (≈1 hour).^{43 (link)}

Experiments were conducted using adult, female Sprague‐Dawley rats (>8 weeks old, >200 g, Taconic Biosciences). Animals were housed in conventional rat cages in the Research Animal Facility under standard environmental conditions (12:12 hour light:dark cycle, 64–78°F, 30–70% humidity, free access to reverse osmosis water, corncob bedding, and food [2918 rodent chow, Envigo]). Animals were anesthetized with 3% to 5% isoflurane; the heart was then excised and transferred to a temperature‐controlled (37°C), constant‐pressure (70 mm Hg) Langendorff‐perfusion system for electrophysiology experiments (Figure 1). After isolating and transferring the heart to the perfusion system, excised hearts were perfused with Krebs‐Henseleit buffer bubbled with carbogen (95% oxygen, 5% CO₂) throughout the duration of the experiment.⁶¹ Pseudo‐ECGs were continuously recorded in lead II configuration during sinus rhythm; ECG signals were analyzed to quantitate heart rate, atrioventricular conduction (PR interval), ventricular depolarization time (QRS width), ventricular repolarization (QTc),⁶² and arrhythmia incidence.⁶³, ⁶⁴, ⁶⁵ Biosignals were acquired in iox2 and ECG parameters were analyzed in ecgAUTO (emka Technologies).