Research Notes: L-arginine

Mitochondrion. 2007 Feb-Apr.
MELAS and L-arginine therapy.
Koga Y, Akita Y, Nishioka J, Yatsuga S, Povalko N, Katayama K, Matsuishi T.
Department of Pediatrics and Child Health, Kurume University School of Medicine, 67 Asahi Machi, Kurume, Fukuoka, Japan.

We investigated the endothelial function in MELAS patients and also evaluated the therapeutic effects of L-arginine. Concentrations of L-arginine during the acute phase of MELAS were significantly lower than in control subjects. L-arginine infusions significantly improved all symptoms suggesting stroke within 30 min, and oral administration significantly decreased frequency and severity of stroke-like episodes. Flow-mediated dilation (FMD) in patients showed a significant decrease than those in the controls. Two years of oral supplementation of L-arginine significantly improved endothelial function to the control levels and was harmonized with the normalized plasma levels of L-arginine in patients. L-arginine therapy showed promise in treating stroke-like episodes in MELAS.

Curr Opin Clin Nutr Metab Care. 2007 Jan.
Effects of L-arginine supplementation on exercise metabolism.
McConell GK.
Department of Physiology, The University of Melbourne, Parkville, Victoria, Australia.

PURPOSE OF REVIEW: To describe the influence of acute and chronic administration of L-arginine on metabolism at rest and during exercise. RECENT FINDINGS: There has been substantial examination of the effect of infusion and ingestion of L-arginine at rest. It has been clearly demonstrated that L-arginine administration improves endothelial function in various disease states. In addition, L-arginine infusion at rest increases plasma insulin, growth hormone, glucagon, catecholamines and prolactin. Such hormonal changes affect metabolism. There has, however, been very little examination of the effect of increases in L-arginine availability during exercise. This is important to study as there is preliminary evidence that L-arginine infusion, probably via increases in nitric oxide (NO), alters skeletal-muscle metabolism during exercise. There is a need for further research, especially to understand the mechanisms of how L-arginine affects exercise metabolism and also to determine whether the hormonal responses that occur in response to L-arginine at rest are also present to some extent during exercise. SUMMARY: This line of research may have important therapeutic implications as there are indications that L-arginine augments the effects of exercise training on insulin sensitivity and capillary growth in muscles.

Neurology. 2006 Jun 13.
Endothelial dysfunction in MELAS improved by l-arginine supplementation.
Koga Y, Akita Y, Junko N, Yatsuga S, Povalko N, Fukiyama R, Ishii M, Matsuishi T.
Department of Pediatrics and Child Health, Kurume University School of Medicine, Fukuoka, Japan.

The authors evaluated endothelial function in patients with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke) by flow-mediated vasodilation (FMD) and found a significant decrease vs controls. Two years of supplementation with oral l-arginine, a nitric oxide precursor, significantly improved endothelial function to control levels and was harmonized with the normalized plasma levels of l-arginine in patients. l-Arginine therapy improved endothelial dysfunction and showed promise in treating strokelike episodes in MELAS.

Neurology. 2005 Feb 22.
L-arginine improves the symptoms of strokelike episodes in MELAS.
Koga Y, Akita Y, Nishioka J, Yatsuga S, Povalko N, Tanabe Y, Fujimoto S, Matsuishi T.
Department of Pediatrics and Child Health, Kurume University School of Medicine, 67 Asahi-Machi, Kurume City, Fukuoka, Japan.

Based on the hypothesis that mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS) are caused by impaired vasodilation in an intracerebral artery, the authors evaluated the effects of administering l-arginine, a nitric oxide precursor. Patients were administered L-arginine intravenously at the acute phase or orally at the interictal phase. L-arginine infusions significantly improved all strokelike symptoms, suggesting that oral administration within 30 minutes of a stroke significantly decreased frequency and severity of strokelike episodes.