Tobacco smoking decreases plasma concentration of the emerging cardiovascular risk marker, L-homoarginine.

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.

Effect of occupational lead exposure on α- and γ-tocopherol concentration in plasma.

OBJECTIVES: Changes in enzymatic antioxidant activity are frequently observed in workers occupationally exposed to lead. Few studies have investigated the influence of lead on the non-enzymatic antioxidant system. The aim of our study was to assess the influence of occupational exposure to lead on the plasma concentration of two hydrophobic forms of vitamin E: α-tocopherol and γ-tocopherol. METHODS: A sample of 401 healthy men, aged 19-62, participated in the study. In total, 340 of these subjects were employed at the Mine and Metallurgical Plant in southern Poland. The workers who were occupationally exposed to lead were divided into quartiles (groups of 85 subjects). The lead concentrations in the blood of the subjects in the control group and in the lead exposure quartiles correspond to the following ranges: 10-72 µg/l (control group); 82-206 µg/l (Q1); 209-308 µg/l (Q2); 308-394 µg/l (Q3) and 395-644 µg/l (Q4), respectively. RESULTS: Significant differences were observed only for the plasma concentration of γ-tocopherol, which differed between the control group and Q1 (by 24.1%, p=0.0368), between Q1 and Q3 (by -18.8%, p=0.0115) and between Q1 and Q4 (by -25.7%, p=0.0002). Multiple linear regression analysis showed that the statistically significant, predictive properties of the γ-tocopherol plasma concentration were as follows: triglycerides (ß=0.440)> age (ß=0.131)> whole cholesterol (ß=0.117)> blood lead concentration (ß=-0.108). For α-tocopherol, significant prognostic properties were triglycerides and total cholesterol (ß=0.485 and ß=0.399, respectively). CONCLUSIONS: Occupational exposure to lead is strongly correlated with the concentration of γ-tocopherol but not α-tocopherol.