TABLE 5.

Utilization of dietary proline and glutamine for the synthesis of citrulline in mice infused with Arg(–) diet for 4 h¹

	Dietary proline	Dietary glutamine
Dietary tracer recovery, μmol tracer·kg−1·h−1
Citrulline	6.7 ± 0.49	1.2 ± 0.07*
Ornithine	7.4 ± 0.53	ND2
Dietary tracer recovery, % of tracer infused
Citrulline	2.9 ± 0.22	0.6 ± 0.04*
Ornithine	3.2 ± 0.22	ND
Dietary contribution, μmol·kg−1·h−1
Citrulline	22.2 ± 1.64	4.0 ± 0.23*
Ornithine	24.7 ± 1.76	ND
Dietary contribution, % of Ra
Citrulline	14.4 ± 0.52	2.9 ± 0.12*
Ornithine	16.5 ± 1.00	ND
Labeled plasma Orn (from dietary tracer) to Cit, μmol tracer·kg−1·h−1	1.56 ± 0.14	ND
Plasma citrulline enrichments, mpe
Due to Orn tracer	1.00 ± 0.05	ND
Measured Cit enrichment	4.32 ± 0.17	0.87 ± 0.04*
Dietary precursor utilization for the synthesis of citrulline, %
At the site of Cit synthesis	23.1 ± 0.56	ND
At the site of Cit synthesis	76.9 ± 0.56	100.0*
Dietary precursor utilization for the synthesis of citrulline, μmol·kg−1·h−1
Through plasma ornithine	5.2 ± 0.45	ND
At the site of Cit synthesis	17.0 ± 1.20	4.0 ± 0.23*

¹Values are means ± SEM, n = 10. *Different from proline, P < 0.001.

²ND, not detectable