Effects of volatile anesthetics on cardiac metabolism in the low-pressure perfused rat heart.

Effects of halothane, enflurane and isoflurane on the myocardial metabolism were studied in the rat heart-lung preparation. Hearts were perfused at a low perfusion pressure (SBP 50 mmHg, DBP 30 mmHg) with succinate or glutamate as substrates. Thirty minutes after the perfusion, intramyocardial ATP, pyruvate, lactate and glycogen were measured enzymatically. Although there was no significant difference in ATP levels of hearts with either substrate, and whether or not volatile anesthetics were present, 1% halothane and 1.5% isoflurane reduced the L/P ratio when succinate was substrate (24.46 +/- 4.81, 17.68 +/- 9.10 vs 39.82 +/- 10.83), and 2% enflurane decreased it when glutamate was substrate (22.25 +/- 10.99 vs 38.44 +/- 6.55). The glycogen levels in volatile anesthetics groups were lower than control when succinate was substrate. The improvement of energy demand-supply balance by inhalation anesthetics may be stronger than their inhibition of electron transport in mitochondria under certain ischemic conditions.