THE BENEFICIAL-EFFECTS OF HEAT-SHOCK FOR PROLONGED HYPOTHERMIC STORAGE

Heat-shock. has been reported to induce tolerance for subsequent ische mia. We wished to determine whether thermal stress is protective for h ypothermic storage. Three groups of Sprague-Dawley rats were studied ( n = 8 per group). Control animals received routine care (CONT) while a naesthetized rats were either warmed to 42 degrees C for 20 min (HEAT) or maintained at room temperature (SHAM). Twenty-four hours later, he arts were mounted on a Langendorff apparatus with an intraventricular balloon. Hearts were then flushed and stored in UW solution for 8 hr a t 0 degrees C and reperfused for 45 min. Data are reported as a percen tage of the prestorage results or as the absolute value (mean +/- SD). Recovery of developed pressure was significantly greater (P < 0.05) i n the heat-shocked animals (79.5 +/- 10.2%) than in the SHAM (63.6 +/- 17.2%) or CONT groups (59.0 +/- 10.8%). Coronary how was similarly en hanced (P < 0.05) in the HEAT group (86.8 +/- 5.5%) vs the CONT (77.0 +/- 12.3%) or SHAM hearts (74.5 +/- 10.2%). Diastolic compliance as as sessed by evaluation of the end-diastolic pressure-volume curves was r educed in all groups (P < 0.0001) but not different among groups. Card iac creatine kinase release during reperfusion was greater in the CONT and SHAM groups (CONT: 726.9 +/- 297.8 IU/g; SHAM: 548.9 +/- 420.9 IU /g) than in the heat-shocked rodents (282.3 +/- 175.5 IU/g, P < 0.05 H EAT vs CONT). Cardiac biopsies were performed sequentially in separate animals (n = 6 per group). Tissue levels of ATP and total adenine nuc leotides were greater in the heat-shacked or SHAM hearts following rep erfusion compared with controls (P < 0.05). Thermal stress provides ad ditional protection for prolonged hypothermic storage. (C) 1996 Academ ic Press, Inc.