Modulation of pulmonary eicosanoid metabolism following exposure to sulfuric acid

Abstract

Eicosanoids (arachidonic acid metabolites) are potent biological mediators. Modulation of their metabolism by air pollutants may be a possible factor in the pathogenesis of environmentally related lung disease. Sulfuric acid (H 2SO 4) aerosols are components of ambient air in many areas. Rabbits were exposed to H 2SO 4 (0.3 μm) at 250, 500, or 1000 μg/m 3 for 1 hr/day for 5 days. They were then euthanized, the lungs lavaged, and eicosanoid analyses performed by radioimmunoassay of acellular lavage fluid. An exposure-concentration-dependent decrease in levels of prostaglandins E 2 and F 2α and thromboxane B 2 was found; no change in leukotriene B 4 was observed. Tracheal explants exposed to acidic environments in vitro also showed reduced production of PGE 2, PGF 2α, and TxB 2. Incubation with sodium sulfate (Na 2SO 4) showed no effect of the sulfate ion (SO 4 2−). This study, the first to examine eicosanoid production after in vivo exposure to pure H 2SO 4 droplets, indicates that such exposure can modulate arachidonic acid metabolism, and that this is likely due to the deposition of hydrogen ion (H +) on target tissue.