Relationship between the rate of citrulline synthesis and bulk changes in the intramitochondrial ATP/ADP ratio in rat-liver mitochondria.
1. The relationship between intramitochondrial and extramitochondrial ATP-utilizing systems and the intramitochondrial ATP/ADP ratio was studied in isolated rat-liver mitochondria. Citrulline synthesis was used as an intramitochondrial ATP-utilizing system, and glucose-6-phosphate synthesis as an extramitochondrial ATP-utilizing system. The intramitochondrial ATP/ADP ratio was manipulated in three ways: with succinate and different concentrations of malonate and/or hexokinase; with 2-oxoglutarate (plus oligomycin) and different concentrations of hexokinase; and with added ATP in uncoupled mitochondria (oligomycin present). 2. Under all conditions used, citrulline synthesis was strictly correlated with the bulk intramitochondrial ATP/ADP ratio. 3. The curve relating citrulline synthesis and intramitochondrial ATP/ADP was shifted towards lower ATP/ADP ratios when the activity of carbamoyl-phosphate synthetase was enhanced by increasing the mitochondrial content of N-acetylglutamate. 4. It is concluded that under the experimental conditions used the intramitochondrial adenine nucleotides behave as a homogeneous pool.
D000244:Adenosine Diphosphate / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002956:Citrulline / Q000096:biosynthesis*; D005971:Glutamates / Q000378:metabolism; D008297:Male; D008314:Malonates / Q000378:metabolism; D008930:Mitochondria, Liver / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D013386:Succinates / Q000378:metabolism
D005971:Glutamates; D008314:Malonates; D013386:Succinates; D002956:Citrulline; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; C016195:N-acetylglutamic acid