Effect of phosphoenolpyruvate on liver mitochondrial calcium retention from fed and fasted rats

Rat liver mitochondria from fed and 4-day-fasted rats are able to accumulate calcium supported by ATP (energy-driven calcium uptake) or by succinate (respiration-driven calcium uptake). Phosphoenolpyruvate decreases the amount of calcium accumulated in both ways, whether the rats were fasted or fed ad libitum. Phosphoenolpyruvate induces a net calcium efflux from mitochondria. The effect of phosphoenolpyruvate is partially reversed by ADP. Phosphoenolpyruvate is also able to inhibit the ATP-driven calcium accumulation in the absence of exogenously added respiratory substrates.