Effect of glutamate-aspartate reperfusion on postischemic neonatal myocardium

We postulated that L-glutamate- and L-aspartate-enriched perfusate would improve functional recovery of postischemic neonatal rabbit hearts.

Isolated working neonatal rabbit hearts were perfused with Krebs-Henseleit buffer and then subjected to 1 hour of hypothermic cardioplegic arrest with St. Thomas' Hospital solution. Hearts were then reperfused with L-glutamate- and L-aspartate-enriched (20 mmol/L) Krebs-Henseleit buffer (AA-enriched Krebs-Henseleit buffer). Hearts reperfused with Krebs-Henseleit buffer alone acted as controls (experiment A). Another group of hearts underwent a similar protocol but were reperfused with the AA-enriched Krebs-Henseleit buffer with correction of the sodium content (experiment B).

Hearts reperfused with AA-enriched Krebs-Henseleit buffer showed a significant decrease in aortic flow at both 15 (p = 0.04) and 30 (p = 0.025) minutes compared with controls. Arrhythmias were frequent. Sodium content of the AA-enriched Krebs-Henseleit buffer was 174 +/- 0.5 mmol/L. In experiment B, hearts reperfused with the AA-enriched Krebs-Henseleit buffer with correction of the sodium content exhibited no difference in aortic flow and cardiac output at either 15 or 30 minutes (p = 0.95 and 0.5 and 0.48 and 0.78, respectively) compared with controls. No arrhythmias were observed. The sodium content of the AA-enriched Krebs-Henseleit buffer was 146 +/- 0.7 mmol/L.

A beneficial effect on functional recovery of neonatal hearts reperfused with AA-enriched Krebs-Henseleit buffer was not demonstrated.