Nitrate Reduction in Whole Saliva

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Abstract
Endogenous and added nitrate is rapidly reduced in incubating saliva. The progressive decrease in salivary and added nitrate is accompanied by a transient accumulation and an apparent subsequent reduction of nitrite. The nitrate-nitrite reductase systems in saliva are present in the particulate fraction, with components of the supernatant serving as electron donors. Yeast extract, pyruvate, or lactate will replace the necessary elements of the hydrogen donor system normally occurring in the supernatant. Formate was only effective as a hydrogen donor for nitrate reduction. Cysteine, cystine, glutathione, glucose, succinate, and thioctic acid were not effective as hydrogen donors for either the nitrate or nitrite reductase systems in salivary sediment. Reduction of nitrate through nitrite in saliva is markedly affected by pH, with maximum activity demonstrated between 6.0 and 6.4. Although nitrate reduction is little affected by oxygen, nitrite reduction is completely inhibited in aerated, incubating saliva. In a limited survey of 40 young adults, no relationship between caries experience (DMF) and the capacity of the individual''s saliva to reduce nitrate through nitrite was found.