The protective effect of enriched branched chain amino acid formulation in the ischemic heart: A phosphorous-31 nuclear magnetic resonance study

Branched chain amino acids (BCAA) have been found to have a protective effect on the ischemic myocardium. Isolated rat hearts were perfused with phosphate-free Krebs-Henseleit (KH) solution with or without BCAA. A Latex balloon-tipped catheter was inserted into the left ventricle to measure intracavitary pressures. Hearts were subjected to 18 minutes of ‘no flow’ global ischemia and then reperfused for 30 mins at 37°C. Metabolism of high energy phosphates during ischemia and recovery was studied by P-31 NMR. Intracellular pH was calculated from the chemical shift of P i. Pressure recovery was better with KH+BCAA (89±16%) than with KH (41±26%) ( P=0.0001); d P/d t recovery was also improved with BCAA (84±19% vs 27±27% for KH) ( P=0.0003). After 18 mins of ischemia, ATP levels in the BCAA group were higher than in the KH perfused hearts (33±20 vs 17±10% of pre-ischemic value) ( P=0.02). No significant difference was found in the intracellular pH at the end of the ischemic period. Following reperfusion the recovery of pH was better in the BCAA group (7.09±0.06 vs 7.04±0.06) ( P=0.03). These results show that BCAA protect the heart from myocardial ischemic injury, decrease depletion of ATP during ischemia, and enhance post-ischemic hemodynamic function.