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[The arginine paradox]
Toshio Nakaki1, Keiichi Hishikawa
1Department of Pharmacology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan. nakaki@med.teikyo-u.ac.jp
Nihon Yakurigaku Zasshi. Folia Pharmacologica Japonica
|February 28, 2002
Summary
The arginine paradox describes how external L-arginine impacts nitric oxide synthase (NOS) activity, even when NOS is theoretically saturated. This suggests complex regulatory mechanisms beyond simple substrate availability are at play.
Area of Science:
- Biochemistry
- Physiology
Context:
- L-arginine is the natural substrate for nitric oxide synthase (NOS).
- Nitric oxide (NO) plays a crucial role in regulating biological functions.
- The "arginine paradox" highlights NOS activity despite theoretical substrate saturation.
Purpose:
- To explore explanations for the "arginine paradox" where exogenous L-arginine influences NO-mediated effects.
- To investigate factors beyond substrate concentration affecting NOS activity.
Summary:
- The arginine paradox describes how external L-arginine affects nitric oxide synthase (NOS) activity, despite NOS being theoretically saturated with L-arginine.
- Potential explanations include L-arginine-induced insulin, membrane transport influencing NOS activity, endogenous NOS inhibitors (like NG, NG-dimethyl-L-arginine and L-citrulline), and intracellular L-citrulline inhibition requiring L-arginine competition.
Impact:
- Understanding the arginine paradox is key to comprehending NO-mediated biological regulation.
- This research informs potential therapeutic strategies involving L-arginine supplementation.