Schwartz R, Topley M, Russell J B
Division of Nutritional Sciences and Agricultural Research Service, U.S. Department of Agriculture, Cornell University, Ithaca, NY 14853.
J Nutr. 1988 Feb;118(2):183-8. doi: 10.1093/jn/118.2.183.
trans-Aconitic acid has been implicated in magnesium deficiency of ruminants since the 1960s, but recent experiments indicated that much of it can be converted by rumen bacteria to tricarballylic acid (TCBA). Rats were used as experimental models in the studies described here because analogous experiments in ruminants would have been very expensive. When TCBA was fed to young male Sprague-Dawley rats as 2% of an AIN-76A diet with marginal (200 mg/kg) or adequate (500 mg/kg) Mg, virtually all of the dietary acid was recovered in the urine. Mg and Ca absorptions were unaffected by TCBA but urinary losses of Mg, Ca and Zn were higher than in pair-fed controls. TCBA was highly correlated (r = 0.93) with titratable acid excretion, and Mg, Ca and Zn retentions were reduced by 90, 35 and 56%, respectively. Rats fed 2% citric acid, a structurally similar but metabolizable acid, excreted more Zn than controls but did not excrete excess Mg or Ca. Since TCBA led to a depletion of Mg and other cations, it could be a contributing factor in the etiology of the Mg deficiency known as grass tetany in ruminants. Additional work in ruminants now seems warranted.
自20世纪60年代以来，反式乌头酸一直被认为与反刍动物的镁缺乏有关，但最近的实验表明，它的大部分可以被瘤胃细菌转化为三羧酸（TCBA）。由于在反刍动物中进行类似实验成本非常高，因此在这里描述的研究中使用大鼠作为实验模型。当将TCBA以2%的比例添加到含有边缘（200毫克/千克）或充足（500毫克/千克）镁的AIN - 76A日粮中喂给年轻雄性斯普拉格 - 道利大鼠时，几乎所有的日粮酸都在尿液中被回收。镁和钙的吸收不受TCBA的影响，但镁、钙和锌的尿排泄量高于配对喂养的对照组。TCBA与可滴定酸排泄高度相关（r = 0.93），镁、钙和锌的保留量分别减少了90%、35%和56%。喂食2%柠檬酸（一种结构相似但可代谢的酸）的大鼠排泄的锌比对照组多，但没有排泄过量的镁或钙。由于TCBA导致镁和其他阳离子的消耗，它可能是反刍动物中称为草痉挛的镁缺乏病因的一个促成因素。现在似乎有必要在反刍动物中开展更多工作。
