Related Experiment Videos
Interrelationships between ureogenesis and gluconeogenesis in perfused rat liver
A Martín-Requero1, G Ciprés, C González-Manchón
1Endocrine Physiology Unit, Centro de Investigaciones Biológicas, C.S.I.C. Madrid, Spain.
Biochimica Et Biophysica Acta
|October 3, 1993
Summary
Ornithine and ammonium chloride inhibit glucose production from lactate in rats by altering pyruvate metabolism. This shift favors urea production over gluconeogenesis, impacting energy balance.
Area of Science:
- Biochemistry
- Metabolic Regulation
Background:
- Ureogenesis and gluconeogenesis are critical metabolic pathways.
- Ornithine and ammonium chloride are key regulators of urea synthesis.
Purpose of the Study:
- To investigate the mechanism by which ornithine and NH4Cl affect gluconeogenesis from lactate and pyruvate.
- To elucidate the role of pyruvate dehydrogenase in this metabolic interplay.
Main Methods:
- Perfused rat liver model.
- Substrate manipulation (lactate, pyruvate, ornithine, NH4Cl).
- Enzyme activity assays (pyruvate dehydrogenase).
Main Results:
- Ornithine/NH4Cl inhibited lactate-derived gluconeogenesis but not pyruvate-derived gluconeogenesis.
- This inhibition was linked to enhanced pyruvate dehydrogenase flux.
- Activation or inhibition of pyruvate dehydrogenase directly impacted ureogenesis and glucose production.
- Ornithine uptake did not correlate with ureogenesis rates.
Conclusions:
- Ornithine and NH4Cl inhibit lactate to glucose flux by promoting pyruvate decarboxylation over carboxylation.
- This metabolic shift favors ureogenesis at the expense of gluconeogenesis.
- Ornithine transport may involve H+ exchange.