Table 5.

Isotopic enrichment of ¹³CO₂ in expired air, carbon dioxide production (VCO₂), ¹³CO₂ output (V¹³CO₂), plasma oxidation rates of arginine and leucine using bicarbonate and glutamate as the precursor pool, and intakes of arginine and leucine following l-[5-¹³C]arginine and l-[1-¹³C]leucine infusions

Parameter	Control group (N = 4)				APF group (N = 6)
	1 week adequate		4 week adequate		1 week adequate		4 week APF
	Fed	Fast	Fed	Fast	Fed	Fast	Fed	Fast
[13C]arg infusion
13CO2 enrichment (APE × 10−3)	7.7 ± 2.3	9.1 ± 1.9	5.6 ± 0.9	7.5 ± 1.5	6.9 ± 1.3	9.5 ± 1.6	3.6 ± 1.2	7.1 ± 2.0
VCO2 (mmol kg−1 h−1)	11.3 ± 1.0	7.7 ± 0.3	8.6 ± 0.8	5.9 ± 0.2	10.6 ± 1.0	7.4 ± 0.2	11.1 ± 2.4	7.3 ± 0.8
V13CO2 ((μmol kg−1 h−1)	1.0 ± 0.3	1.0 ± 0.3	1.0 ± 0.3	0.9 ± 0.3	0.9 ± 0.2	1.0 ± 0.2	0.5 ± 0.2	0.7 ± 0.2
Arg ox ((μmol kg−1 h−1)	25.2 ± 5.4a	16.9 ± 3.9	24.6 ± 5.6a	15.6 ± 3.5	23.3 ± 7.5a	18.3 ± 5.3	7.1 ± 3.7a,b	12.8 ± 3.2
Dietary Arg. intake ((μmol kg−1 h−1)	35 ± 1.2	0	35 ± 1.2	0	37 ± 15	0	0	0
[13C]leu infusion
13CO2 enrichment (APE × 10−3)	10.4 ± 0.8	9.5 ± 1.2	10.2 ± 0.5	11.5 ± 0.5	11.0 ± 2.3	10.7 ± 1.9	10.5 ± 1.3	9.8 ± 0.4
VCO2 (mmol kg−1 h−1)	11.3 ± 0.8	7.2 ± 0.3	8.7 ± 1	5.6 ± 0.5	10.5 ± 0.9	7.9 ± 0.8	10.2 ± 2.5	6.8 ± 1.2
V13CO2 (μmol kg−1 h−1)	1.3 ± 0.2	1.1 ± 0.2	0.7 ± 0.3	0.7 ± 0.3	1.4 ± 0.3	1.1 ± 0.1	1.2 ± 0.2	0.9 ± 0.1
Leu ox (μmol kg−1 h−1)	24 ± 5.9a	14.0 ± 4.0	20.3 ± 9a	12.1 ± 5.3	35.0 ± 7.6a	20.6 ± 4.7	35.9 ± 11a	15.9 ± 4.7
Dietary Leu. intake (μmol kg−1 h−1)	62.1 ± 2.1	0	62 ± 1.8	0	65.8 ± 14	0	65.7 ± 13	0

All values are mean ± SD.

^aP < 0.05 by mixed model ANOVA, fed vs. fast within each study period at 1 or 4 weeks for control or APF group.

^bP < 0.05 by mixed model ANOVA. Change between week 1 and week 4 of the Control or APF groups, for a given state (fed or fasted).