Hepatic metabolites and amino acid levels during adaptation of rats to a high protein, carbohydrate-free diet.

Changes in hepatic levels of lactate, pyruvate, phosphoenolpyruvate (PEP), alpha-ketoglutarate, malate, oxaloacetate, ketone bodies, alanine, serine, glycine, aspartate, glutamate, glutamine, valine, urea, adenine nucleotides and inorganic phosphate were examined in rats consuming a high protein, carbohydrate-free diet for up to 40 days. While some components showed transient changes, others (pyruvate, malate, oxaloacetate, PEP, ketone bodies, alanine, glycine, glutamine, valine, urea, adenine nucleotides and inorganic phosphate) were permanently altered. The cytoplasmic and mitochondrial redox states were only transiently affected and by day 24 were not different from control values. In contrast, the cytoplasmic phosphorylation state was affected from day 1 on; this suggests a role for the latter in permanently reorienting metabolism toward gluconeogenesis and ureogenesis.