Advances in Molecular Toxicology: Chapter Four. Nitrogen Oxides Toxicology of the Aerodigestive Tract

Umeo Takahama · Toshihiro Ansai · Sachiko Hirota

ส.ค. 2013 · Advances in Molecular Toxicology หนังสือเล่มที่ 7 · Elsevier Inc. Chapters

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Salivary nitrate derived from foods is reduced to nitrite and nitric oxide (NO•) by oral bacteria. NO• is transformed into NO2•, N2O3, and ONOOH by chemical reactions, and nitrite is oxidized to NO2• by salivary peroxidase. The formation of reactive nitrogen oxides becomes faster with the decrease in pH of dental plaque from 7 to 5. Reactive nitrogen oxides formed in acidified plaque can activate leukocytes through oxidation, nitration, and nitrosation of free and bacterial proteins in plaque and the gingival crevice. O2•− and NO• produced by activated leukocytes can contribute to stresses to the gingival tissues. This chapter deals with mechanisms of production of reactive nitrogen oxides in the oral cavity, especially, acidified plaque. Since salivary nitrite is transported to the stomach, this chapter also deals with reactions of salivary nitrite in the stomach.