BACKGROUND: Tobacco smoking is one of the most important risk factors for cardiovascular disease (CVD) and few biomarkers have been linked to the increased risk of CVD and tobacco smoking. Tobacco smoke has been shown to elevate the plasma levels of asymmetric dimethylarginine (ADMA), a metabolite of L-arginine and an endogenous inhibitor of endothelial nitric oxide synthase. The other potential biomarker that has not been studied to date is L-homoarginine, a homolog of L-arginine. The aim of this study was to evaluate the effects of cigarette smoking on L-homoarginine and other CVD biomarkers. METHODS AND RESULTS: In a cross-sectional study of 231 healthy male volunteers, we measured plasma levels of L-homoarginine, L-arginine, and ADMA using the HPLC method. In smokers, we found that plasma L-homoarginine levels were 16.7% lower compared with nonsmokers after adjusting for age, body mass index, plasma creatinine, and metal blood levels (P<0.05). Plasma ADMA levels were only 6.0% higher in smokers when compared with the levels found in nonsmokers (P>0.05). CONCLUSIONS: Our results suggest that, in contrast to ADMA, there is a strong association between exposure to tobacco smoke and plasma L-homoarginine levels. Further research in this field is needed to explain the mechanisms of the relationship of low L-homoarginine levels, smoking, and cardiovascular health.
BACKGROUND:Tobacco smoking is one of the most important risk factors for cardiovascular disease (CVD) and few biomarkers have been linked to the increased risk of CVD and tobacco smoking. Tobacco smoke has been shown to elevate the plasma levels of asymmetric dimethylarginine (ADMA), a metabolite of L-arginine and an endogenous inhibitor of endothelial nitric oxide synthase. The other potential biomarker that has not been studied to date is L-homoarginine, a homolog of L-arginine. The aim of this study was to evaluate the effects of cigarette smoking on L-homoarginine and other CVD biomarkers. METHODS AND RESULTS: In a cross-sectional study of 231 healthy male volunteers, we measured plasma levels of L-homoarginine, L-arginine, and ADMA using the HPLC method. In smokers, we found that plasma L-homoarginine levels were 16.7% lower compared with nonsmokers after adjusting for age, body mass index, plasma creatinine, and metal blood levels (P<0.05). Plasma ADMA levels were only 6.0% higher in smokers when compared with the levels found in nonsmokers (P>0.05). CONCLUSIONS: Our results suggest that, in contrast to ADMA, there is a strong association between exposure to tobacco smoke and plasma L-homoarginine levels. Further research in this field is needed to explain the mechanisms of the relationship of low L-homoarginine levels, smoking, and cardiovascular health.