Figure 1. Nitrate concentration (µg/mL) in mixed saliva, serum, and urine of miniature pigs before and after nitrate loading. Data are given as mean ± SD (n = 5). , control group, no KNO₃ treatment; •, test group, no KNO₃ treatment; , control group, KNO₃ treatment; , test group, KNO₃ treatment. (A) Mixed saliva samples. Concentration of nitrate in the test group (bilateral ablation of the parotid glands) is significantly lower than that in the control group before and after nitrate loading (p < 0.05). Higher concentration of nitrate was induced by nitrate loading in both groups (p < 0.05). (B) Serum samples and (C) urine samples. Similar concentrations of nitrate were detected in both groups before nitrate loading. Higher concentrations of nitrate were induced by nitrate loading. The concentration of nitrate in the test group was much higher than that in the control group after nitrate loading (P < 0.001).