In vivo 14C isotopic evaluation of amino acid oxidative catabolism in the growing chick. I. Fast respiratory 14CO2 and acetyl-CoA renewal.
A single dose of [1-14C] or [U-14C]glycine or L-[1-14C] or [U-14C]valine was injected intraperitoneally into 1- and 3-week-old chicks. Continuous automatic determination of respiratory 14CO2 and determination of 14C in excreta and uric acid were carried out for 8 h. Computer-aided analysis of the kinetics of respiratory 14CO2 demonstrated two exponentially decreasing components, 'fast 14CO2' and slow 14CO2'. Fast 14CO2 production represents the immediate oxidation and/or decarboxylation of the 14C-labeled amino acid. The half-lives differed according to the nature of the 14C-labeled amino acid but not to the age of the chick. The size of the acetyl-CoA pool labeled by [14C]glycine was between 10 and 15 mmol/100 g of chick. Metabolic partition of a circulating plasma free amino acid between oxidation and retention could be quantified by an isotopic index.
Simonnet
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Institut National des Sciences et Techniques Nucléaires, CEN Saclay, Gif-sur-Yvette, France.
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Auliac
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Jacob
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Pascaud
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D000105:Acetyl Coenzyme A / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D002245:Carbon Dioxide; D002250:Carbon Radioisotopes; D002645:Chickens; D005998:Glycine / Q000378:metabolism; D010084:Oxidation-Reduction; D012119:Respiration; D014527:Uric Acid / Q000378:metabolism; D014633:Valine / Q000378:metabolism
D000596:Amino Acids; D002250:Carbon Radioisotopes; D002245:Carbon Dioxide; D014527:Uric Acid; D000105:Acetyl Coenzyme A; D014633:Valine; D005998:Glycine