ABSTRACT
Arginine (Arg) is a non-essential amino acid for healthy adults. It is the precursor of nitric oxide (NO). Previous reports show that Arg and NO possess numerous physiological properties. Many studies have demonstrated the benefi ts of Arg supplementation on immune functions. Arg is considered to be an essential amino acid for patients with catabolic conditions. Currently, Arg is added to enteral formulas in an attempt to modulate immune function and improve clinical outcomes of critically ill patients. Adhesion molecules are important mediators of host defense and are localized in the earliest infl ammatory lesions. Numerous studies have shown that Arg, possibly through the regulation of NO, modulates the expression of adhesion molecules and hence attenuates the infl ammatory reaction. Th is chapter appraises several animal studies and current clinical evidence regarding the eff ects of Arg supplementation on adhesion molecule expression in various conditions. Some in vitro studies using an NO donor and NO synthase inhibitors to investigate the roles of NO in leukocyte adherence and immigration are also included. Most studies suggested that Arg and/or NO administration can reduce adhesion molecule expression and decrease leukocyte adherence and transmigration. Th e mechanisms through which NO decreases endothelial and leukocyte adhesion molecule expressions are postulated. However, confl icting results in some situations have been reported, and discrepancies between diff erent experiments with Arg or NO administration are discussed.
