Increase in Anclotensln-Converting Enzyme in Rat Lungs Following Inhalation of Phosgene

Conceptual approaches for treatment of phosgene inhalation-induced lung injury

Toxic industrial chemicals are used throughout the world to produce everyday products such as household and commercial cleaners, disinfectants, pesticides, pharmaceuticals, plastics, paper, and fertilizers. These chemicals are produced, stored, and transported in large quantities, which poses a threat to the local civilian population in cases of accidental or intentional release. Several of these chemicals have no known medical countermeasures for their toxic effects. Phosgene is a highly toxic industrial chemical which was used as a chemical warfare agent in WWI. Exposure to phosgene causes latent, non-cardiogenic pulmonary edema which can result in respiratory failure and death. The mechanisms of phosgene-induced pulmonary injury are not fully identified, and currently there is no efficacious countermeasure. Here, we provide a proposed mechanism of phosgene-induced lung injury based on the literature and from studies conducted in our lab, as well as provide results from studies designed to evaluate survival efficacy of potential therapies following whole-body phosgene exposure in mice. Several therapies were able to significantly increase 24h survival following an LCt50-70 exposure to phosgene; however, no treatment was able to fully protect against phosgene-induced mortality. These studies provide evidence that mortality following phosgene toxicity can be mitigated by neuro- and calcium-regulators, antioxidants, phosphodiesterase and endothelin receptor antagonists, angiotensin converting enzymes, and transient receptor potential cation channel inhibitors. However, because the mechanism of phosgene toxicity is multifaceted, we conclude that a single therapeutic is unlikely to be sufficient to ameliorate the multitude of direct and secondary toxic effects caused by phosgene inhalation.

BHA diet enhances the survival of mice exposed to phosgene: the effect of BHA on glutathione levels in the lung

Phosgene-induced pulmonary edema formation has been under investigation for many years. One mechanism of protection may involve the use of antioxidants. Previously, it has been shown that butylated hydroxyanisole (BHA) treatment can enhance glutathione (GSH) levels. The present study focused on dietary supplementation in mice using BHA, a phenolic compound used in food preservation. Three groups of male CD-1 mice were studied: group 1, control animals fed with Purina rodent chow 5002; group 2, fed 0.75% BHA (w/w) in 5002; and group 3, fed 1.5% BHA (w/w) in 5002. Mice were fed for 22 days. On day 23 mice were exposed to 32 mg/m(3) phosgene for 20 min in a whole-body exposure chamber. Survival rate (SR) and odds ratio (OR) were determined at 12 and 24 h. In mice that died within 12 h, the lungs were removed immediately and lung wet weights (WW), dry weights (DW), lung wet weight/body weight ratio (LWW/BW), and lung tissue total glutathione (GSH) were assessed. For 12-h data, 6 mice from the 1.5% BHA group were sacrificed for lung tissue measurements. The SR for 0.75% BHA was 80% at 12 h and 55% at 24 h, compared with 36% and 23%, respectively, for controls. For 1.5% BHA, the 12- and 24-h SR were 100% and 92%, respectively. Odds ratios of 6.9 for 0.75% BHA and 46.6 for 1.5% BHA at 12 h and 4.0 and 42 for 0. 75% and 1.5% BHA, respectively, at 24 h were significantly (chi2) higher than control diet phosgene-exposed mice. Dietary pretreatment with 0.75% and 1.5% BHA significantly enhanced lung tissue GSH, 1.8-fold (p < or =.01) and 5.8-fold (p < or =.01), respectively, compared with phosgene-exposed control diet. Both BHA-supplemented diets significantly reduced WW. Only 1.5% BHA reduced DW, a measure of lung hyperaggregation. and LWW/BW compared with control diet. In air-exposed controls, BHA induced a dose-responsive decrease in WW, DW, LWW/BW ratio, and GSH. In conclusion, dietary pretreatment with BHA at the two dose levels reduced lung edema and lethality by enhancing lung tissue GSH in mice exposed to phosgene.