L-Homoarginine and cardiovascular disease

Purpose of review An increasing number of reports indicate that low levels of the endogenous amino acid L-homoarginine are linked to cardiovascular disease. In this article, we review the current findings regarding L-homoarginine metabolism and (patho-) physiology with a focus on its clinical impact. Recent findings Recent clinical and epidemiological studies revealed a strong association of low circulating L-homoarginine with cardiovascular outcomes and mortality. Human and murine studies identified L-arginine: glycine amidinotransferase (AGAT) as the responsible enzyme for endogenous L-homoarginine formation, suggesting a further important function of AGAT apart from its involvement in creatine and energy metabolism. Further studies related L-homoarginine to smoking and hypertension, and metabolic phenotypes. Summary AGAT deficiency results in diminished intracellular energy stores (i.e., ATP and phosphocreatine), as well as a lack of L-homoarginine, and has been linked to an improved metabolic risk profile, but also to impaired cardiac and cerebrovascular function. L-homoarginine's structural similarity to L-arginine suggested physiological interference with L-arginine pathways (e.g., nitric oxide). Animal experiments and clinical trials are needed to improve knowledge on the physiology of L-homoarginine and differentiate its role as marker and mediator in cardiovascular disease.