Understanding heart metabolism during preservation is crucial to develop new effective cardioplegic solutions. We aim to investigate metabolic alterations during heart preservation in the clinically used Celsior (Cs) and histidine buffer solution (HBS). We also focused in gender-specific metabolic adaptations during ischemia. We followed energy metabolism in hearts from men and women preserved during 6 hours in Cs and HBS. Hearts were subjected to cold ischemia (4°C) in Cs or HBS, and aliquots of the cardioplegic solution were collected throughout preservation for nuclear magnetic resonance analysis. HBS-preserved hearts from men consumed glucose mostly between 240 and 360 minutes, whereas HBS-preserved hearts from women consumed glucose throughout the 6 hours of ischemia. Lactate production rates followed approximately the glucose consumption rates in HBS-preserved hearts. The lactate to alanine ratio, an indicator of the redox state, was increased in HBS-preserved hearts when compared with Cs-preserved hearts. Hearts from men presented a higher redox state than those from women preserved in Cs after 300 minutes. Both Cs and HBS were capable of preventing acidification in hearts from women but not in hearts from men, which decreased the extracellular pH. HBS-preserved hearts from men and women produced 0.1 ± 0.01 and 0.15 ± 0.03 μmol·min(-1)·gdw(-1) of lactate, respectively. Those rates were significantly higher than in Cs-preserved hearts. Thus, Cs was more effective in preventing lactate production. We conclude that glycolysis and lactate production are stimulated in HBS-preserved hearts. HBS shows better overall results particularly in hearts from women, which presented less extracellular acidification and were more effective in recycling the metabolic subproducts.