Factors modifying ischemic injury in the isolated rat heart.

The extent of ischemic injury has been studied in the isolated working rat heart utilizing an aortic ball valve that reduces the coronary flow. A number of factors were tested including high heart rate, noradrenaline, acidosis, alkalosis, high afterload, beta-blockade, glucose-insulin-potassium (GIK), palmitate and methylprednisolone. Mechanical performance, myocardial contents of ATP, creatine phosphate, glycogen and lactate and the leakage of creatine phosphokinase (CK) from the myocardium to the perfusion buffer were measured and used for determination of the ischemic injury. Tachycardia, noradrenaline and palmitate are factors that markedly increase the ischemic injury in this preparation. GIK and probably metoprolol decrease the release of CK compared with the controls.