Involvement of salivary glands in regulating the human nitrate and nitrite levels

Abstract

Objective To study the dynamic fluctuations of nitrate and nitrite content in humans following damage to major salivary glands. Methods Fifteen nasopharyngeal carcinoma patients, scheduled to undergo IMRT, were recruited. The prescription dose to GTV, CTV1 and CTV2, was 68, 60 and 54 Gy, respectively, in 30 fractions, 1 fraction/day. Saliva, serum and urine samples were collected at baseline, RT10, RT20 and at endpoint of radiation. Ions concentration was determined using ion chromatography. Results Salivary flow rates and nitrate content decreased over time ( p < 0.0001), whereas serum and urinary nitrite rose. Salivary nitrite increased transiently and then plateaued. Cumulative irradiation dose to salivary glands correlated with nitrate content in serum ( p < 0.0001), but not in saliva and urine ( p = 0.876 and p = 0.175). The salivary flow rates correlated to the nitrate content in serum ( p < 0.0001), but not in saliva and urine ( p = 0.230 and p = 0.428). Conclusions Nitrate and nitrite contents in saliva, serum or urine changed in response to salivary gland damage. Salivary glands are associated with the metabolism of both ions in humans. The decreased serum nitrate appears to provide adjuvant information about salivary dysfunction.