[The arginine paradox]

Nihon Yakurigaku Zasshi. 2002 Jan;119(1):7-14. doi: 10.1254/fpj.119.7.
[Article in Japanese]

Abstract

L-Arginine has attracted major interest because it has been identified as the natural substrate of nitric oxide synthase and is now recognized as a major player in the regulation of biological function. The arginine paradox refers to the phenomenon that exogenous L-arginine causes NO-mediated biological effects despite the fact that nitric oxide synthases (NOS) are theoretically saturated with the substrate L-arginine. There have been several explanations for this phenomenon, although none of them can explain the arginine paradox fully: (1) L-arginine-induced insulin, which has vasodilatory actions. (2) Neither extracellular nor intracellular concentration determines the NOS activity but rather the L-arginine amount transported across the plasma membrane may do so. (3) Endogenous NOS inhibitors reduce the enzyme sensitivity to L-arginine. These inhibitors include, NG, NG-dimethyl-L-arginine, L-citrulline, argininosuccinic acid and agmatine. (4) Intracellular L-citrulline, an NOS product, is a potent inhibitor of NOS so that the cells may need extra L-arginine to compete with L-citrulline inhibition.

Publication types

  • English Abstract
  • Review

MeSH terms

  • Animals
  • Arginine / pharmacology
  • Arginine / physiology*
  • Humans
  • Nitric Oxide Synthase / antagonists & inhibitors
  • Nitric Oxide Synthase / metabolism*

Substances

  • Arginine
  • Nitric Oxide Synthase