Cardiac storage with University of Wisconsin solution, calcium, and magnesium

Previous investigations from this institution and others support the role of University of Wisconsin solution for prolonged hypothermic cardiac storage. Modification of the divalent cation concentrations has been beneficial for cardioplegic investigations and may enhance cardiac recovery after extended preservation.

To investigate this hypothesis, isolated rodent hearts were obtained from Sprague-Dawley rats and mounted on a Langendorff apparatus. Rat hearts were flushed (15 ml/kg) and stored (30 ml) for 8 hours at 0 degree C in unmodified 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 reperfusion with an intraventricular balloon.

Developed pressure (mean +/- standard deviation) was increased with calcium 0.1 mmol/L (University 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 concentration (10 mmol/L) was significantly harmful (developed pressure: 58.3% +/- 8.4%, p < 0.05; creatine kinase release: 408 +/- 200 versus 170 +/- 104 IU/gm, p < 0.05; lactate dehydrogenase release: 103 +/- 43 versus 37 +/- 26 IU/gm, p < 0.05). Coronary flow recovered to control values with magnesium 15 mmol/L, which was significantly greater than that achieved with unmodified University of Wisconsin solution (97.1% +/- 14.6% versus 72.1% +/- 8.4%, p < 0.05). Of the calcium-magnesium combinations tested, developed pressure was increased compared with unmodified University of Wisconsin solution with calcium 0.1 and magnesium 20 mmol/L (76.8% +/- 6.4%, p < 0.05). Diastolic function was reduced in all groups (p < 0.0001) and not significantly different between groups.

The experiments indicated that recovery after storage with University of Wisconsin solution is enhanced with the addition of calcium and magnesium. The addition of high concentrations of calcium (> or = 2.5 mmol/L) appears harmful.