To begin, place an anesthetized rat in a supine position. Secure the limbs of the animal with tape. Then fix a nose cone over the animal to administer oxygen.
Soak sterile gauze in a container with Krebs-Henseleit buffer. Place the soaked gauze on ice. After making a lateral incision across the abdomen, move the stomach and intestines to allow access to the left renal vein.
Inject heparin and apply pressure to the injection site until the bleeding stops. After letting the heparin circulate for a couple of minutes, cut through the rib cage on either side and across the diaphragm to completely open the chest cavity. Carefully lift the heart-lung block, and cut along the descending aorta, keeping the aortic arch intact.
Transfer the heart-lung block to the Krebs-Henseleit buffer ice slush to arrest the heart.
