Fig. 3.

The effect of arginine and citrulline supplementation. Values are expressed as means±SEMs. Arginine flux increased after arginine (49.6±3.0→111.1± 6.9 μmol·kg⁻¹·h⁻¹, p<0.001) and citrulline (50.0±3.1→130.0±9.1 μmol·kg⁻¹·h⁻¹, p<0.001) supplementation. Arginine clearance did not show significant differences after arginine (16.3±1.1→14.5±1.4 mL·kg⁻¹·min⁻¹) and citrulline (16.2±1.1→13.5±1.5 ml·kg⁻¹·min⁻¹) supplementation. Citrulline flux increased after arginine (5.9±0.5→7.0±0.7 μmol·kg⁻¹·h⁻¹, p<0.05) and citrulline (5.5±0.5→46.3±4.0 μmol·kg⁻¹·h⁻¹, p<0.001) supplementation. Citrulline clearance did not show significant differences after arginine (5.3±0.6→5.4±0.7 mL·kg⁻¹·min⁻¹) and citrulline (4.6±0.3→9.9±2.8 ml·kg⁻¹·min⁻¹) supplementation. De novo arginine synthesis rate increased after arginine (3.7±0.4→4.9±0.6 μmol·kg⁻¹·h⁻¹, p<0.05) and citrulline (3.3±0.3→31.1±3.0 μmol·kg⁻¹·h⁻¹, p<0.001) supplementation. Percentage of arginine flux derived from de novo synthesis decreased after arginine supplementation (7.5±0.7→4.4±0.6%, p<0.001) and increased after citrulline supplementation (6.8±0.8→24.1±1.9%, p<0.001). The NO synthesis rate measured by arginine-to-citrulline flux increased after arginine (0.072±0.011→0.146±0.021 μmol·kg⁻¹·h⁻¹, p<0.001) and citrulline (0.062±0.007→0.517±0.188 μmol·kg⁻¹·h⁻¹, p<0.05) supplementation. The NO synthesis rate measured by ASR of NOx increased after arginine (0.37±0.06→0.62±0.13 μmol·L plasma⁻¹·h⁻¹, p<0.05) and citrulline (0.36±0.06→0.93±0.27 μmol·L plasma⁻¹·h⁻¹, p<0.05) supplementation.