Mirvish S S, Patil K, Ghadirian P, Kommineni V R
J Natl Cancer Inst. 1975 Apr;54(4):869-75.
To help understand how intragastric nitrosation forms N-nitroso compounds, nitriet disappearance from the rat stomach was measured after food containing nitrite was given. In preliminary experiments, nitrite disappearance from buffered aqueous solutions became more rapid as the pH was lowered from 5 to 1 and, at a given pH, was more rapid in a slurry of commercial rat food. The disappearance of nitrite from buffer was little affected by the addition of pepsin, mucin, albumin, or rat gastric contents. When starved rats were given 5 g food with 1.82 mg nANO3/g, nitrate was not reduced to nitrite in the stomach. Five g food containing 154 mug NaNO2/g was administered similarly, and the total stomach (T) and glandular and nonglandular parts (G and NG) were analyzed after 1.5 hours. Weight and nitrite concentration of the stomach contents dropped linearly and the amount of nitrite dropped exponentially (with a half-life of 1.4 hr). Mean nitrite concentration in G was less than half that in NG. From similar experiments with phenol red, emptying accounted for 60% of nitrite loss from T. In G, nitrite concentration was reduced about 3 times due to dilution and 3 times due to other causes. Conditions in G, e.g., nitrite concentration, pH, and empyting time, were discussed in relation to carcinogenesis experiments with nitrite plus amines and amides.
为了帮助理解胃内亚硝化作用如何形成N-亚硝基化合物，在给予含亚硝酸盐的食物后，测定了大鼠胃内亚硝酸盐的消失情况。在初步实验中，随着pH从5降至1，缓冲水溶液中亚硝酸盐的消失速度加快，并且在给定pH下，市售大鼠食物的浆液中亚硝酸盐消失得更快。缓冲液中亚硝酸盐的消失受胃蛋白酶、粘蛋白、白蛋白或大鼠胃内容物添加的影响很小。当给饥饿的大鼠喂食每克含1.82毫克硝酸钠的5克食物时，胃内硝酸盐不会还原为亚硝酸盐。同样给予每克含154微克亚硝酸钠的5克食物，1.5小时后分析整个胃（T）以及腺部和非腺部（G和NG）。胃内容物的重量和亚硝酸盐浓度呈线性下降，亚硝酸盐的量呈指数下降（半衰期为1.4小时）。G部的平均亚硝酸盐浓度不到NG部的一半。通过对酚红的类似实验，排空占T部亚硝酸盐损失的60%。在G部，亚硝酸盐浓度因稀释降低约3倍，因其他原因降低约3倍。结合亚硝酸盐加胺类和酰胺类的致癌实验，讨论了G部的条件，如亚硝酸盐浓度、pH和排空时间。
