Decreased Lung Function and Altered Nitrate Formation after High Auto/Truck Emission Inhalation during Exercise

Abstract

Transient lung function improvement after exercise is common in healthy individuals. Exercise while breathing high emission aerosols exacerbates the asthmatic response. Lung endothelial nitric oxide synthase (eNOS) is upregulated after exercise. However, in vitro studies show decreased eNOS activity from diesel emission particle exposure but in vivo studies show that particle exposure is marginally associated with increases in exhaled nitric oxide (eNO). Nitrite/nitrate has been used as an estimate of NO production. PURPOSE: To examine acute effects of emission particulate matter (PM) inhalation during exercise on lung function, exhaled NO and exhaled breath condensate (EBC) nitrate (NO3) and S-nitrosoglutathione (GSNO) levels. METHODS: Twelve physically fit non-asthmatic college aged males performed random order exercise while breathing high PM or low PM ambient air. Thirty min exercise bouts were performed at 80-90% HRmax. Lung function was measured pre, 5, 10, 15 min post-exercise. EBC and eNO were collected pre- and 1 h post-exercise. NO and NO3 levels were determined by chemiluminescence and GSNO was measured spectrophotometric ally. RESULTS: Fall in lung function was significantly greater after high PM than after low PM exposure exercise (−3.3±0.8 vs −0.9±0.54 and −7.3±2.2 vs 3.0±2.2; FEV1 and FEF25–75, p= 0.0002 and 0.004, respectively). No differences in eNO at 50 ml·s-1 flow rate were found. GSNO increased ∼50% after low PM exercise and decreased ∼5% after high PM exercise but significant difference was not achieved. EBC NO3 post-exercise change was different between PM conditions (+35% vs −40%, p=0.04). Percent change in FEV1 was correlated to pre- to post- differences in eNO and NO3 (r=0.62,p=0.002 and r=0.55,p=0.08; respectively) but not to GSNO. CONCLUSIONS: PM inhalation during exercise causes decreased lung function and decreased EBC nitrate levels in non-asthmatics. Nitrate levels in EBC could prove to be a useful marker of NO stress from acute emissions inhalation.