Fig. 3.
Deuterium enrichments in serum-free and protein-bound alanine (E[M + 1]) and in serum water (E2H2O). The symbols are M + 1 enrichments of free alanine in serum (△; n = 2–4/time point at left y-axis) and M + 1 enrichments of serum protein-bound alanine (▽; n = 4–12/time point at left y-axis) and deuterium enrichment of serum water (◇; n = 4–12/time point at right y-axis) from rats grown for 42 days on 8% volume deuterium-enriched drinking water. Values are means ± SE, although the error bars may be smaller than the symbols. A nonparametric 1-way ANOVA (Kruskal-Wallis) test was performed to define the time point when 2H enrichment was in isotopic steady state in each pool. Alanine deuterium enrichments were in isotopic steady state from days 14 to 42 in serum both free and protein bound, whereas the water enrichment fluctuated slightly more but had equilibrated in the body water pool by day 7. The mean deuterium enrichment for serum-free alanine at steady state is shown as a dashed line (20.66 ± 0.17%) and for body water as a solid line (5.20 ± 0.17%).