Citrate Transport in Guinea Pig Heart Mitochondria

Guinea pig heart mitochondria loaded with [14C]citrate show exchanges of radioactivity at 30 °C with added citrate, L-malate and phosphoenolpyruvate. These exchanges are inhibited by benzene-1,2,3-tricarboxylate.Measurements of rates of citrate transport indicate that the activity of this transporting system is low in heart mitochondria compared to that observed in liver mitochondria. The Km values obtained indicate a similarity to those obtained in liver. Citrate oxidation by coupled mitochondria was also found to be slow at 30 °C but was inhibited by benzene-1,2,3-tricarboxylate. The role of mitochondrial citrate transport in control of glycolytic flux in the heart is discussed.