TABLE 6.
Methionine kinetics (in μmol · kg−1 · h−1) during pregnancy1
| Nonpregnant | First trimester | Second trimester | Third trimester | P2 | |
| Ra | |||||
| m1 Tracer | |||||
| Fasted | 21.12 ± 4.90 (8) | 18.25 ± 2.73 (10) | 20.53 ± 4.36 (5) | 22.66 ± 4.96 (10) | NS |
| Fed | 35.15 ± 5.47 (8) | 28.99 ± 3.34 (10) | 32.85 ± 9.39 (5) | 34.11 ± 4.74 (5) | NS |
| Ra | |||||
| m3 Tracer | |||||
| Fasted | 24.68 ± 6.38 (8) | 21.34 ± 7.53 (10) | 24.68 ± 8.28 (5)3 | 39.70 ± 6.75 (10)4 | <0.001 |
| Fed | 47.69 ± 17.52 (8) | 36.88 ± 15.41 (10) | 43.88 ± 20.60 (5) | 61.61 ± 15.26 (5) | NS |
| Transsulfuration | |||||
| Fasted | 2.16 ± 0.61 (8) | 3.45 ± 0.76 (10)34 | 2.92 ± 0.49 (4) | 2.56 ± 0.91 (9) | 0.004 |
| Fed | 8.38 ± 1.93 (8) | 11.52 ± 2.12 (10)4 | 9.45 ± 3.05 (4) | 9.13 ± 1.89 (4) | 0.036 |
| Remethylation | |||||
| Fasted | 6.16 ± 6.82 (7) | 5.68 ± 6.09 (8)3 | 8.06 ± 9.92 (4) | 17.04 ± 8.65 (10)4 | 0.021 |
| Fed | 17.04 ± 16.96 (7) | 12.10 ± 12.21 (8) | 17.47 ± 21.46 (4) | 27.51 ± 15.69 (5) | NS |
| Transmethylation | |||||
| Fasted | 8.18 ± 6.84 (7) | 9.04 ± 5.70 (8)3 | 10.98 ± 9.44 (4) | 19.21 ± 9.58 (9)4 | 0.067 |
| Fed | 25.18 ± 17.33 (7) | 23.80 ± 11.76 (8) | 26.92 ± 19.96 (4) | 35.48 ± 19.31 (4) | NS |
1
All values are means ± SDs; n in parentheses. Ra, rate of appearance; m1 tracer, [1-13C]methionine; m3 tracer, [C2H3]methionine.
2
Obtained by using Kruskal-Wallis one-factor ANOVA.
3
P < 0.05 compared with third trimester subjects (Mann-Whitney U test).
4
P < 0.05 compared with nonpregnant subjects (Mann-Whitney U test).