PRESERVATION/REPERFUSION INJURY IN THE RAT CARDIAC TRANSPLANT MODEL. I. HTK VERSUS UW IN PROLONGED ISCHEMIA

Abstract

444 Background: Cold ischemia/reperfusion (CIR) injury limiting cold storage time of cardiac allografts is influenced by various combinations of protective agents in organ preservation solutions. Preservation efficiencies were compared of histidine-tryptophan-ketoglutarate (HTK) and University of Wisconsin (UW) solutions in a syngeneic heterotopic heart transplant model with prolonged cold ischemia time prior to reperfusion. Methods: After retrograde transaortal perfusion, hearts were stored in either HTK (group 1, N=10) or UW (group 2, N=9) on ice at 4 °C for 10 hours. Reduced glutathione was added to both preservation solutions in 5 cases of each group. A second period of ischemia during rewarming was deliberately kept at 60 min, during which organs were cooled topically, aiming at comparability with the clinical setting. After 24 h reperfusion, graft function was scored by palpation and microscopic inspection upon laparotomy. (0) no contractions, (1) no contraction at palpation and minimal contractions at microscopic inspection, (2) weak or partial contractions detectable by palpation, (3) homogenous contraction of the ventricle at low intensity (frequency or amplitude), to (4) normal atrial and ventricular contraction intensity. Mitochondrial function was quantified in small samples of permeabilized cardiac muscle fibers by high-resolution respirometry (OROBOROS Oxygraph). Results: Average heart scores were 2.3 ± 0.7 and 2.9 ± 1.2 after 10 h cold preservation in HTK and UW solution (±SD; P>0.05). Freshly added glutathione did not significantly change the outcome with either preservation solution. Heart scores between 1 and 4 of individual grafts were tightly correlated with damage of mitochondrial respiratory capacities, amounting up to 90 % reduction of ADP-stimulated complex I respiration. Conclusion: The model applied is suitable for the quantitative assessment of preservation solutions. For up to 10 hours, HTK and UW yield similar results which are not significantly improved by the addition of reduced glutathione.