Inhibition of gluconeogenesis by extracellular ATP in isolated rat hepatocytes.
The aim of this study was to determine the effect of externally added ATP on gluconeogenesis by isolated hepatocytes from starved rats. High concentrations of extracellular ATP inhibited gluconeogenesis from lactate and pyruvate but not from glycerol or fructose. This inhibition was associated with an increase in intracellular adenosine contents. ADP, AMP, or adenosine but not guanosine 5'triphosphate, inosine 5' triphosphate, or adenine also inhibited gluconeogenesis. alpha, beta-Methylene-ATP, a nonmetabolizable structural analogue of ATP, did not affect the rate of gluconeogenesis. Intracellular ATP levels were increased by externally added ATP or adenosine, but ATP-to-ADP ratios in the cytosolic and mitochondrial compartments were diminished. Malate and phosphoenolpyruvate contents were decreased by extracellular ATP or adenosine. Our results show that inhibition of gluconeogenesis by high levels of extracellular ATP may be mediated by adenosine derived from ATP catabolism at the plasma membrane.
Asensi
M
M
Departamento de Fisiología, Universitat de Valencia, Spain.
Lopez-Rodas
A
A
Sastre
J
J
Viña
J
J
Estrela
J M
JM
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D005632:Fructose / Q000378:metabolism; D005943:Gluconeogenesis / Q000187:drug effects*; D005990:Glycerol / Q000378:metabolism; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid; D051381:Rats; D011919:Rats, Inbred Strains
D007773:Lactates; D011773:Pyruvates; D005632:Fructose; D019344:Lactic Acid; D000244:Adenosine Diphosphate; D019289:Pyruvic Acid; D000255:Adenosine Triphosphate; D005990:Glycerol