Beneficial effects of hypothermic reperfusion on metabolic and functional recovery after cold storage of the rat heart.

With an isolated rat heart preparation, we evaluated the effects of hypothermic reperfusion on myocardial metabolic and functional recovery after cold storage. Hearts in group 1 were reperfused at normothermia (35 degrees C) after 3 hours of cold (5 degrees C) storage, and hearts in group 2 were reperfused at 20 degrees C and gradually rewarmed to 35 degrees C during 20 minutes of Langendorff (nonworking) perfusion. Coronary vascular resistance in group 1 increased progressively, whereas that in group 2 tended to decrease during the early period of reperfusion. Total creatine kinase leakage during the initial 20 minutes of reperfusion was less in group 2 (0.87 +/- 0.13 IU/heart) than in group 1 (2.48 +/- 0.32 IU/heart, p less than 0.01). Hearts in group 2 showed a better recovery of energy charge (0.850 +/- 0.020) than did those in group 1 (0.787 +/- 0.013, p less than 0.05) at 5 minutes of reperfusion. Adenosine triphosphate (ATP) and total adenine nucleotide contents in group 2 exceeded those in group 1 (ATP, 18.0 +/- 1.8 and 13.4 +/- 0.8 mumol/gm dry weight; total adenine nucleotide, 22.7 +/- 1.5 and 17.8 +/- 1.0 mumol/gm dry weight, respectively, both p less than 0.05) at 20 minutes of reperfusion. Functional recovery at 60 minutes of reperfusion was better in group 2 than in group 1 (50.3 +/- 5.8% and 30.6 +/- 4.2%, respectively, p less than 0.01). These findings indicate that hypothermic reperfusion reduces the extent of myocardial damage and improves the oxygen supply and demand balance during the early period of reperfusion; hence there is a better recovery of heart function.