McKinley-Barnard Sarah, Andre Tom, Morita Masahiko, Willoughby Darryn S
Department of Health, Human Performance, and Recreation, Baylor University, Exercise and Biochemical Nutritional Lab, 76798 Waco, TX USA.
Function Research Group, Healthcare Products Development Center, KYOWA HAKKO BIO CO., LTD., 2, Miyukigaoka, 305-0841 Tsukuba, Ibaraki Japan.
J Int Soc Sports Nutr. 2015 Jun 10;12:27. doi: 10.1186/s12970-015-0086-7. eCollection 2015.
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.
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.
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).
Combining L-citrulline with GSH augments increases in nitrite and NOx levels during in vitro and in vivo conditions.
一氧化氮（NO）由L-精氨酸和L-瓜氨酸内源性合成。由于其对一氧化氮合酶（NOS）的作用，还原型谷胱甘肽（GSH）可能有助于防止NO的氧化还原。本研究确定了L-瓜氨酸和/或GSH对啮齿动物和人类体内以及体外条件下指示NO合成的标志物的有效性。
在第一阶段，用0.3 mM L-瓜氨酸、1 mM GSH（Setria®）或0.3 mM的二者组合处理人脐静脉内皮细胞（HUVECs）。在第二阶段，将8周龄的Sprague-Dawley大鼠随机分为3组，分别通过口服灌胃给予纯净水、L-瓜氨酸（500 mg/kg/天）或L-瓜氨酸（500 mg/kg/天）与GSH（50 mg/kg/天）的组合，持续3天。采集血样并评估血浆NOx（亚硝酸盐+硝酸盐）。在第三阶段，将进行抗阻训练的男性随机分配，使其口服纤维素安慰剂（2.52 g/天）、L-瓜氨酸（2 g/天）、GSH（1 g/天）或L-瓜氨酸（2 g/天）+GSH（200 mg/天），持续7天，然后进行涉及肱二头肌3组10次重复最大负荷（10-RM）的抗阻训练。采集静脉血并用于评估血浆环磷酸鸟苷（cGMP）、亚硝酸盐和NOx。
在第一阶段，用L-瓜氨酸和GSH处理的细胞中的亚硝酸盐水平显著高于对照组（p<0.05）。在第二阶段，L-瓜氨酸+GSH组的血浆NOx显著高于对照组和L-瓜氨酸组（p<0.05）。在第三阶段，血浆cGMP有所升高，但不显著（p>0.05）。然而，与安慰剂相比，运动后30分钟时L-瓜氨酸+GSH组的亚硝酸盐和NOx显著更高（p<0.05）。
在体外和体内条件下，将L-瓜氨酸与GSH联合使用可提高亚硝酸盐和NOx水平。
