一氧化二氮使维生素B12失活对大鼠骨髓、肾脏、大脑和肝脏中叶酸辅酶水平的影响。

Effect of nitrous oxide inactivation of vitamin B12 on the levels of folate coenzymes in rat bone marrow, kidney, brain, and liver.

作者信息

Wilson S D, Horne D W

出版信息

Arch Biochem Biophys. 1986 Jan;244(1):248-53. doi: 10.1016/0003-9861(86)90114-1.

Abstract

The effects of nitrous oxide inactivation of the vitamin B12-dependent enzyme, methionine synthetase, on the distribution of folic acid derivatives in rat bone marrow cells, kidney, brain, and liver were determined. Methionine synthetase activity was decreased by about 90% in bone marrow cells, kidney, and brain and by 83% in liver. The proportion of 5-methyltetrahydrofolate (5-CH3-H4PteGlu) in N2O-exposed rats increased from 1.4- to 1.9-fold depending on the tissue examined. This increase was at the expense of a decrease in different folate derivatives in different tissues--in bone marrow cells, kidney, and liver 5-HCO-H4PteGlu, 10-HCO-H4PteGlu, and H4PteGlu decreased; in brain only H4PteGlu decreased significantly. Total endogenous folates, as measured by Lactobacillus casei after conjugase treatment, were unchanged in all tissues after nitrous oxide exposure. The results are interpreted as direct support of the methyl trap hypothesis as the explanation of the interrelationship of folate and vitamin B12 metabolism in bone marrow cells, kidney, and brain, as well as in liver.

摘要

测定了一氧化二氮使维生素B12依赖性酶甲硫氨酸合成酶失活对大鼠骨髓细胞、肾脏、脑和肝脏中叶酸衍生物分布的影响。骨髓细胞、肾脏和脑中的甲硫氨酸合成酶活性降低了约90%，肝脏中降低了83%。根据所检查的组织不同，暴露于一氧化二氮的大鼠体内5-甲基四氢叶酸（5-CH3-H4PteGlu）的比例增加了1.4至1.9倍。这种增加是以不同组织中不同叶酸衍生物的减少为代价的——在骨髓细胞、肾脏和肝脏中，5-HCO-H4PteGlu、10-HCO-H4PteGlu和H4PteGlu减少；在脑中只有H4PteGlu显著减少。经结合酶处理后用干酪乳杆菌测定的总内源性叶酸在一氧化二氮暴露后所有组织中均未改变。这些结果被解释为直接支持甲基陷阱假说，该假说解释了骨髓细胞、肾脏、脑以及肝脏中叶酸和维生素B12代谢的相互关系。