Endogenous flux of nitric oxide: Citrulline is preferred to Arginine

Both arginine (Arg) and its precursor citrulline (Cit) have received much interest in the past two decades because of their potential effects on whole‐body nitric oxide (NO) production and augmentation of NO‐dependent signalling pathways. However, the usefulness of Arg supplementation for NO product...

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Bibliographic Details
Published in:Acta Physiologica 2021-03, Vol.231 (3), p.e13572-n/a
Main Authors: Bahadoran, Zahra, Mirmiran, Parvin, Kashfi, Khosrow, Ghasemi, Asghar
Format: Article
Language:English
Subjects:
Arginase
Arginine
Citrulline
Dietary supplements
Enzymes
Intestinal absorption
Intestine
Localization
Nitric oxide
Nitric-oxide synthase
Reabsorption
Signal transduction
Urea
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Summary:Both arginine (Arg) and its precursor citrulline (Cit) have received much interest in the past two decades because of their potential effects on whole‐body nitric oxide (NO) production and augmentation of NO‐dependent signalling pathways. However, the usefulness of Arg supplementation for NO production is questionable because of its high splanchnic first pass metabolism (FPM), which limits its systemic availability. Both hepatic‐ and extrahepatic arginases critically limit the availability of Arg for the NO synthase enzymes (NOSs) and therefore, a limited amount of oral Arg can reach the systemic circulation for NO synthesis. Arg also has some undesired effects including induction of arginase activity, an increase of urea levels, a decrease of cellular uptake of Cit and decrease of recycling of Arg from Cit. In contrast, Cit has more availability as an NO precursor because of its high intestinal absorption, low FPM and high renal reabsorption. At the cellular level, co‐localization of Cit transport systems and the enzymes involved in the Cit‐Arg‐NO pathway facilitates channelling of Cit into NO. Furthermore, cells preferably use Cit rather than either intra‐ or extracellular Arg to improve NO output, especially in high‐demand situations. In conclusion, available evidence strongly supports the concept that Cit leads to higher NO production and suggests that Cit may have a better therapeutic effect than Arg for NO‐disrupted conditions.
ISSN:1748-1708
1748-1716
DOI:10.1111/apha.13572