TABLE 3.
Glutamine and citrulline fluxes and contribution of glutamine to citrulline synthesis in humans, pigs, rats, and mice1
| Species |
|||||
| Humans (n = 4) | Pigs (n = 5) | Rats (n = 6) | Mice (n = 5) | P | |
| Flux,2 μmol ⋅ kg−1 ⋅ h−1 | |||||
| Glutamine ([2H5] tracer) | 423 ± 252,d | 882 ± 39c | 3789 ± 162a | 3228 ± 89b | <0.001 |
| Glutamine (2-[15N] tracer) | 320 ± 13d | 663 ± 31c | 2565 ± 109a | 1989 ± 54b | <0.001 |
| Citrulline | 10.6 ± 2.3d | 46.5 ± 3.1c | 197.5 ± 11a | 81.1 ± 4.7b | <0.001 |
| Glutamine contribution to citrulline synthesis,3 % of citrulline flux | |||||
| Glutamine M+1 to citrulline M+1 | 87.7 ± 8.4a | 46.3 ± 3.3b | 56.5 ± 3.0b | 59.6 ± 3.7b | <0.001 |
| 2-[15N]-glutamine to 2-[15N] | 48.3 ± 5.0a | 28.0 ± 2.3b | 35.0 ± 2.9a,b | 28.9 ± 4.0b | <0.001 |
| [2H5] glutamine to [2H5]-citrulline | 9.7 ± 0.9b | 3.4 ± 0.4c | 16.7 ± 0.8a | 14.4 ± 0.8a | <0.001 |
1
Values are means ± SEMs. Means in the same row with different superscript letters differ, P < 0.05.
2
Glutamine flux determined with the [2H5] tracer was greater (P < 0.001) than that calculated by using the [2-15N] tracer.
3
The contribution of glutamine to citrulline synthesis differed (P < 0.001) depending on the tracer and fragment used to determine isotope enrichment.