Effects of pH on the cold preservation of the isolated rat heart

Storage solutions of varying pH have been used for the simple cold preservation of the heart for transplantation. However, few studies have focused on the optimal pH for a storage solution. In the present study, we investigated the effects of storage solutions with 5 different pHs (6.60, 7.00, 7.40, 7.80, and 8.20 at 4 degrees C) on cardiac function, the leakage of cytosolic enzymes, and the myocardial metabolites content. We used the isolated perfused working rat heart model and a 6-hour preservation period in the different storage solutions. We found that cardiac function was best preserved at a pH of 7.00 or 7.80. In the hearts preserved at a pH of 7.00 or 7.80, the leakage of creatine kinase and lactate dehydrogenase was significantly less than at a pH of 7.40 (p less than 0.01). ATP was maintained at a significantly higher concentration in the pH 7.00 solution as compared with the other solutions (p less than 0.01). No significant differences were observed in the creatine phosphate and lactate levels among the five different pH groups. The results showed that the cardiac function and other parameters of cold-preserved hearts were relatively well maintained at both a pH of 7.00 and 7.80, suggesting the possible existence of a biphasic optimum pH for cold preservation.