Effects of Carbon Dioxide on Activity of Apple Mitochondria

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Abstract
Effects of CO(2) on mitochondrial activity of apple (Malus pumila Mill. var. Richared Delicious) were studied in two ways. Immediate effects were determined by imposing 3 to 18% CO(2)-bicarbonate mixtures on isolated apple mitochondria, and long term effects were determined by extracting mitochondria from apples that had been stored for intervals in atmospheres containing 6 or 12% CO(2) plus 3% O(2). The CO(2)-bicarbonate systems had immediate and broad effects on mitochondrial oxidations: 18% CO(2) stimulated malate oxidation about 10%; suppressed alpha-ketoglutarate, citrate, and NADH oxidations about 10%; and suppressed fumarate, pyruvate, and succinate oxidations about 32%. The effects of lower CO(2) concentrations varied with substrates. Mitochondria isolated from fruit stored in 6 or 12% CO(2) possessed a reduced capacity to oxidize added succinate or NADH, but retained a marked sensitivity to CO(2)-bicarbonate mixtures. Respiratory control in these mitochondria was somewhat reduced, but CO(2) had not acted as a strong uncoupling agent.