MITOCHONDRIAL PYRUVATE METABOLISM IN LIVER AND KIDNEY DURING ACIDOSIS

Pyruvate transport and carboxylation have been determined in mitochond ria from liver and kidney cortex isolated from Wistar rats with acidos is produced by three different treatments: fasting, exercise and inges tion of ammonium chloride. Fasting for 48 h or swimming for 2 h result ed in an increased rate of CO2 fixation by mitochondria from both orga ns incubated with pyruvate. This increase was accompanied by a rise in the rate of pyruvate transport in all cases except in mitochondria de rived from the kidney of the fasted animals. Acute acidosis produced b y the ingestion of ammonium chloride resulted in increases in pyruvate transport and carboxylation in kidney mitochondria, but a drop in pyr uvate carboxylation was observed in mitochondria from the liver. The r esults are discussed in terms of the differential regulation of the mi tochondria steps for gluconeogenesis from three carbon precursors in l iver and kidney, taking into consideration the hormonal status of the animals and the prevailing available substrates in each condition.