Langendorff-perfused rabbit hearts

Explanted hearts from normal, healthy New Zealand White rabbits (male; 3.0–3.5 kg; Charles River Canada, Inc, Sherbrooke, Quebec, Canada) were used in these experiments. Following anesthesia with isoflurane, hearts were explanted through a midline thoracotomy. Each excised heart was then cannulated and mounted to a Langendorff setup, and perfused with a buffer solution consisting of (in mM) NaCl 130, CaCl₂ 2.2, KCl 4.4, MgSO₄ 0.3, NaHCO₃ 24, NaH₂PO₄ 1.2, and glucose 12, and bubbled with 95% oxygen and 5% CO₂. The perfusion pressure of ∼70 mm Hg and temperature of 37°C were maintained. Two silver electrodes on a plastic seat for the perfused heart were used for recording pseudo-surface electrocardiograph throughout the entire experimental period. An additional pair of electrodes were used for electrical stimulation/pacing.