ARS | Publication request: Precursors for the synthesis of citrulline in mice fed arginine free diets

Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: February 1, 2010
Publication Date: April 6, 2010
Citation: Marini, J.C., Didelija, I.C., Castillo, L., Brendan, L. 2010. Precursors for the synthesis of citrulline in mice fed arginine free diets [abstract]. Journal of Federation of American Societies for Experimental Biology. 24:740.26.

Technical Abstract: Dietary arginine (Arg) is the main dietary precursor for citrulline (Cit) synthesis. To test the hypothesis that the contribution of dietary proline (Pro) and glutamine (Gln) increases during the feeding of an Arg free diet, rates of appearance (Ra) and precursor-intermediate-product relationships were established by the infusion of tracers in conscious mice. There was no difference in RaCit or RaArg due to the lack of Arg in the diet (152 and 564 µmol/kg–1/ h–1, resp.); however, Ra ornithine (Orn) was greater in the Arg sufficient diet (332 vs. 180 µmol/kg–1/ h–1). There was an increase in the utilization of plasma Orn for the synthesis of Cit (47 vs. 34 µmol/kg–1/ h–1) in the Arg free diet. There was no difference in the utilization of plasma Arg between the two diets for Cit synthesis, either through plasma Orn (26 µmol/kg–1/ h–1) or at the site of citrulline synthesis (13 µmol/kg–1/ h–1). The contribution of dietary Pro to the synthesis of Cit was mainly at the site of Cit production rather than through plasma Orn (16.7 and 4.6 µmol/kg–1/ h–1, resp.). Dietary Gln was utilized only at the site of Cit synthesis (4 µmol/kg–1/ h–1). Dietary Gln and Pro increased their contribution to the synthesis of Cit during Arg free feeding, but still remained a minor source, despite the absence of Arg in the diet. Endogenous Arg and Orn are able to support Cit synthesis during Arg free feeding.