L-citrulline and Glutathione supplementation combination
Combined L-citrulline and glutathione supplementation increases the concentration of markers indicative of nitric oxide synthesis
McKinley-Barnard S, Andre T, Morita M2, Willoughby DS. J Int
Soc Sports Nutr.2015 Jun 10;12:27. doi: 10.1186/s12970-015-0086-7. eCollection
2015.
Background
Nitric oxide (NO) is endogenously synthesized from
L-arginine and L-citrulline. Due to its effects on nitric oxide synthase (NOS),
reduced glutathione (GSH) may protect against the oxidative reduction of NO.
The present study determined the effectiveness of L-citrulline and/or GSH on
markers indicative of NO synthesis in in vivo conditions with rodents and
humans and also in an in vitro condition.
Methods
In phase one, human umbilical vein endothelial cells
(HUVECs) were treated with either 0.3 mM L-citrulline, 1 mM GSH (Setria®) or a
combination of each at 0.3 mM. In phase two, Sprague-Dawley rats (8 weeks old)
were randomly assigned to 3 groups and received either purified water,
L-citrulline (500 mg/kg/day), or a combination of L-citrulline (500 mg/kg/day)
and GSH (50 mg/kg/day) by oral gavage for 3 days. Blood samples were collected
and plasma NOx (nitrite + nitrate) assessed. In phase three, resistance-trained
males were randomly assigned to orally ingest either cellulose placebo (2.52
g/day), L-citrulline (2 g/day), GSH (1 g/day), or L-citrulline (2 g/day) + GSH
(200 mg/day) for 7 days, and then perform a resistance exercise session
involving 3 sets of 10-RM involving the elbow flexors. Venous blood was
obtained and used to assess plasma cGMP, nitrite, and NOx.
Results
In phase one, nitrite levels in cells treated with
L-citrulline and GSH were significantly greater than control (p < 0.05). In
phase two, plasma NOx with L-citrulline + GSH was significantly greater than
control and L-citrulline (p < 0.05). In phase three, plasma cGMP was
increased, but not significantly (p > 0.05). However, nitrite and NOx for
L-citrulline + GSH were significantly greater at 30 min post-exercise when
compared to placebo (p < 0.05).
Conclusions
Combining L-citrulline with GSH augments increases in nitrite and NOx levels during in vitro and in vivo conditions.
Link: http://www.ncbi.nlm.nih.gov/pubmed/26097441