Assessment of ischemic injury and protective interventions: the Langendorff versus the working rat heart preparation.

The isolated rat heart is widely used for investigating ischemia and evaluating protective interventions, particularly with global ischemia, in which Langendorff and working preparations have formed the cornerstone of much of the developmental work on cardioplegic solutions. The objective of the present study was to compare the vulnerability of the two preparations to global ischemia and their responsiveness to protection with the St Thomas' Hospital cardioplegic solution. Langendorff preparations (n = 6) were subjected to 15, 30, 45, 60, 75, 90, 105 or 120 mins of global ischemia, and working preparations (n = 6) to 10, 15, 20, 25, 30, 35, 40 or 45 mins of global ischemia; post ischemic recovery of cardiac function, creatine kinase leakage, tissue ATP and creatine phosphate content were measured. With 30 mins of global ischemia, the impairment of cardiac function was similar in both preparations. With reperfusion in the Langendorff, the left ventricular developed pressure (LVDP), maximum rate of pressure development (dP/dt), heart rate and coronary flow recovered to 54.7 +/- 5.7, 53.7 +/- 7.1, 88.9 +/- 3.0 and 67.2 +/- 1.8%, respectively, of their pre-ischemic control value. In working hearts, cardiac output, heart rate and coronary flow recovered to 17.9 +/- 2.5, 95.6 +/- 4.2 and 73.8 +/- 8.2%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)