Metabolomic and mass isotopomer analysis of liver gluconeogenesis and citric acid cycle. I. Interrelation between gluconeogenesis and cataplerosis; formation of methoxamates from aminooxyacetate and ketoacids.
We conducted a study coupling metabolomics and mass isotopomer analysis of liver gluconeogenesis and citric acid cycle. Rat livers were perfused with lactate or pyruvate +/- aminooxyacetate or mercaptopicolinate in the presence of 40% enriched NaH(13)CO(3). Other livers were perfused with dimethyl [1,4-(13)C(2)]succinate +/- mercaptopicolinate. In this first of two companion articles, we show that a substantial fraction of gluconeogenic carbon leaves the liver as citric acid cycle intermediates, mostly alpha-ketoglutarate. The efflux of gluconeogenic carbon ranges from 10 to 200% of the rate of liver gluconeogenesis. This cataplerotic efflux of gluconeogenic carbon may contribute to renal gluconeogenesis in vivo. Multiple crossover analyses of concentrations of gluconeogenic intermediates and redox measurements expand previous reports on the regulation of gluconeogenesis and the effects of inhibitors. We also demonstrate the formation of adducts from the condensation, in the liver, of (i) aminooxyacetate with pyruvate, alpha-ketoglutarate, and oxaloacetate and (ii) mercaptopicolinate and pyruvate. These adducts may exert metabolic effects unrelated to their effect on gluconeogenesis.
Yang
Lili
L
Department of Nutrition, Case Western Reserve University, Cleveland, Ohio 44106, USA.
Kombu
Rajan S
RS
Kasumov
Takhar
T
Zhu
Shu-Han
SH
Cendrowski
Andrea V
AV
David
France
F
Anderson
Vernon E
VE
Kelleher
Joanne K
JK
Brunengraber
Henri
H
D000625:Aminooxyacetic Acid / Q000378:metabolism*; D000818:Animals; D002247:Carbon Isotopes / Q000378:metabolism; D002952:Citric Acid Cycle; D005943:Gluconeogenesis; D007651:Keto Acids / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D010084:Oxidation-Reduction; D019289:Pyruvic Acid / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013386:Succinates / Q000378:metabolism
D002247:Carbon Isotopes; D007651:Keto Acids; D013386:Succinates; D000625:Aminooxyacetic Acid; D019344:Lactic Acid; D019289:Pyruvic Acid; C056451:dimethyl succinate