PRESERVATION of mammalian organs by hypothermia requires methods of cooling and warming that will maintain uniform temperature distribution throughout the tissues, yet permit changes in temperature at a sufficiently rapid rate to equalize physical stress and minimize variations in biochemical reaction rates.3 The freezing of cells has been most successful when performed relatively slowly (in the range of 1 to 10 C per minute) in the temperature range from 0 to 20 C with rapid freezing thereafter. This present work has sought the limits of freezing of organs with best available techniques and protective agents.
Albino rats averaging 200 gm received 25 mg pentobarbital (Nembutal) and 5 mg sodium heparin intraperitoneally. The aorta was severed and an aortic cannula was lodged just above the coronary arteries. The heart and lungs were removed in toto and placed on a modified Langendorff perfusion column (Fig 1). After perfusion commenced the