Arginine in critical care: Preclinical aspects

Abstract

Understanding the multiple biological roles of arginine and/or its metabolites is essential towards understanding the potential therapeutic use of these molecules in the critically ill patient. Arginine is a conditionally essential amino acid that through its multiple metabolic pathways can play diverse biological roles. For example, as a precursor of nitric oxide, it can play significant functions in vasodilation, hemodynamic stability, and platelet aggregation. As an amino acid, arginine is essential for normal T lymphocyte function. Arginine is also central in the detoxification of ammonia. Perhaps the most significant breakthrough in the last 10 years is the identification of arginase 1 expression in cells of the immune system – namely, myeloid cells; through regulation of arginine availability, arginase 1 serves to modulate nitric oxide production and T lymphocyte function. Pathologic expression of arginase 1 is observed in a growing number of illnesses leading to a state of arginine deficiency. Replacement of arginine during pathologic states of arginine deficiency may be beneficial under certain clinical conditions.