CARDIAC STORAGE WITH UNIVERSITY-OF-WISCONSIN SOLUTION, CALCIUM, AND MAGNESIUM

Background: Previous investigations from this institution and others s upport the role of University of Wisconsin solution for prolonged hypo thermic cardiac storage. Modification of the divalent cation concentra tions has been beneficial for cardioplegic investigations and may enha nce cardiac recovery after extended preservation. Methods: To investig ate this hypothesis, isolated rodent hearts were obtained from Sprague -Dawley rats and mounted on a Langendorff apparatus. Rat hearts were f lushed (15 ml/kg) and stored (30 ml) for 8 hours at 0 degrees C in unm odified University of Wisconsin solution (n = 16/group) or University of Wisconsin solution with calcium concentrations of 0.025 to 10 mmol/ L or magnesium concentrations of 10 to 20 mmol/L (six to eight hearts/ group). Finally, combinations of calcium and magnesium were examined. Rat hearts were studied before storage and after 45 minutes of reperfu sion with an intraventricular balloon. Results: Developed pressure (me an +/- standard deviation) was increased with calcium 0.1 mmol/L (Univ ersity of Wisconsin solution: 69.2% +/- 7.0%; Ca++ 0.1 mmol/L: 78.9% /- 6.1%, p < 0.05), whereas only the addition of the highest calcium c oncentration (10 mmol/L) was significantly harmful (developed pressure : 58.3% +/- 8.4%, p < 0.05; creatine kinase release: 408 +/- 200 versu s 170 +/- 104 IU/gm, p < 0.05; lactate dehydrogenase release: 103 +/- 43 versus 37 +/- 26 IU/gm, p < 0.05). Coronary flow recovered to contr ol values with magnesium 15 mmol/L, which was significantly greater th an that achieved with unmodified University of Wisconsin solution (97. 1% +/- 14.6% versus 72.1% +/- 8.4%, p < 0.05). Of the calcium-magnesiu m combinations tested, developed pressure was increased compared with unmodified University of Wisconsin solution with calcium 0.1 and magne sium 20 mmol/L (76.8% +/- 6.4%, p < 0.05). Diastolic function was redu ced in all groups (p < 0.0001) and not significantly different between groups. Conclusions: The experiments indicated that recovery after st orage with University of Wisconsin solution is enhanced with the addit ion of calcium and magnesium. The addition of high concentrations of c alcium (greater than or equal to 2.5 mmol/L) appears harmful.