Background: The role of the salivary glands in the maintenance of nitrate and nitrite in saliva is poorly understood. The aim was to study alterations of nitrate and nitrite metabolisms in patients with Sjogren's syndrome (SS) or sialosis.
Methods: Saliva, serum, and urine samples were collected from healthy volunteers (n = 29), patients with SS (n = 31), and patients with sialosis (n = 30). Concentrations of nitrate and nitrite were determined by high-performance liquid chromatography (HPLC).
Results: In the healthy group, the highest concentration of nitrate was found in parotid saliva (172 mg/l), followed by urine (160 mg/l), whole saliva (97 mg/l), and serum (33 mg/l). In the SS group, concentration of nitrate was decreased in parotid saliva and whole saliva, and increased significantly in urine. Concentration of nitrite in whole saliva was significantly decreased in the SS group and increased in the sialosis group.
Conclusion: Hypofunction of the salivary glands is associated with significant changes of nitrate and nitrite levels in the saliva and urine.