Arginine metabolism in rat enterocytes.
Rat enterocytes exposed to L-arginine in the absence of any other exogenous substrate were found to actively metabolize this cationic amino acid. L-Arginine was converted to L-citrulline either directly in a NADPH-sensitive manner thought to be coupled with the generation of NO, or indirectly through the sequence of reactions catalyzed by arginase and ornithine transcarbamylase. A large fraction of L-citrulline and L-ornithine generated from exogenous L-arginine was released in the incubation medium. The production of CO2 and (poly)amines from L-arginine occurred at rates 2 to 3 orders of magnitude lower than that characterizing the net uptake of the cationic amino acid, and this despite the fact that enterocytes were equipped to allow the interconversion of L-ornithine and L-glutamate. It is concluded that the oxidative catabolism of L-arginine in enterocytes is quantitatively negligible relative to its conversion to L-citrulline and L-ornithine.
Blachier
F
F
Laboratory of Experimental Medicine, Brussels Free University, Belgium.
Darcy-Vrillon
B
B
Sener
A
A
Duée
P H
PH
Malaisse
W J
WJ
D000818:Animals; D001120:Arginine / Q000378:metabolism*; D002956:Citrulline / Q000378:metabolism; D005260:Female; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D009952:Ornithine / Q000378:metabolism; D010084:Oxidation-Reduction; D011700:Putrescine / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013095:Spermidine / Q000378:metabolism; D013096:Spermine / Q000378:metabolism; D014508:Urea / Q000378:metabolism
D002956:Citrulline; D013096:Spermine; D014508:Urea; D001120:Arginine; D009952:Ornithine; D013095:Spermidine; D011700:Putrescine