Dietary citrulline but not ornithine counteracts dietary arginine deficiency in rats by increasing splanchnic release of citrulline.
Ornithine and citrulline have different arginine-sparing capabilities when provided in an arginine-deficient diet. Rats were fed arginine-deficient diets containing ornithine or citrulline to see the effect on net fluxes of free arginine, ornithine and citrulline across the portal-drained viscera (PDV) and liver. The diets contained either 10 g arginine/kg diet (+Arg) or no arginine: the -Arg/+Ala diet contained additional alanine and the -Arg/+Orn and -Arg/+Cit diets contained ornithine and citrulline, respectively, in amounts isomolar to the amount of arginine in the control (+Arg) diet. Blood arginine concentrations were 50% lower than control values (P < 0.001) in rats fed the -Arg/+Ala or the -Arg/+Orn diet. However, addition of citrulline to the arginine-deficient diet restored blood arginine concentrations. The source of the circulating arginine in the rats fed the -Arg/+Cit diet was neither the PDV nor the liver; net splanchnic uptake of arginine was 0.3 mumol/min. Net citrulline release was substantial from the PDV (0.65 mumol/min) as well as from the splanchnic bed (0.67 mumol/min) of rats fed the -Arg/+Cit diet, such that blood citrulline concentrations were more than double (P < 0.001) those in rats fed the +Arg or -Arg/+Orn diet. Splanchnic release of citrulline in rats fed the -Arg/+Cit diet but not in rats fed the -Arg/+Orn diet supported the production of arginine in non-splanchnic organs such as, presumably, the kidney.
Hartman
W J
WJ
U.S. Department of Agriculture, Tufts University, Boston, MA 02111.
Torre
P M
PM
Prior
R L
RL
D000409:Alanine / Q000097:blood; D000596:Amino Acids / Q000097:blood; D000641:Ammonia / Q000097:blood / Q000652:urine; D000818:Animals; D001120:Arginine / Q000172:deficiency*; D001783:Blood Flow Velocity; D001835:Body Weight; D002956:Citrulline / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology*; D003404:Creatinine / Q000652:urine; D004032:Diet; D005502:Food; D018698:Glutamic Acid / Q000097:blood; D005973:Glutamine / Q000097:blood; D008297:Male; D009952:Ornithine / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D009963:Orotic Acid / Q000652:urine; D011392:Proline / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D013152:Splanchnic Circulation; D014508:Urea / Q000097:blood / Q000652:urine
D000596:Amino Acids; D005973:Glutamine; D002956:Citrulline; D018698:Glutamic Acid; D009963:Orotic Acid; D000641:Ammonia; D014508:Urea; D001120:Arginine; D011392:Proline; D003404:Creatinine; D009952:Ornithine; D000409:Alanine