Yager Claire, Ning Cong, Reynolds Robert, Leslie Nancy, Segal Stanton
Metabolic Research Laboratory, The Children's Hospital of Philadelphia, and the Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Mol Genet Metab. 2004 Feb;81(2):105-11. doi: 10.1016/j.ymgme.2003.10.001.
Under conditions of dietary galactose loading, mice deficient in galactose-1-phosphate uridyltransferase (GALT) accumulate large amounts of galactitol and galactonate in heart and skeletal muscle. In contrast to liver, brain, and kidney, which form little galactitol when GALT-deficient animals (G/G) ingest a 40% galactose diet, heart and skeletal muscle galactitol reaches 22.90+/-1.62 (M+/-SE) and 38.88+/-2.62 micromol/g tissue, respectively, levels 40-100 times that of galactose-1-phosphate (Gal-1-P). Sixteen-day-old suckling G/G mice accumulate galactitol in heart and to a lesser extent, in skeletal muscle. Heart and skeletal muscle of G/G mice also form galactonate, with levels comparable to that of liver, which was presumed previously to be the only tissue capable of converting galactose to galactonate under conditions of loading. The data suggest that heart and skeletal muscle play a role in disposition of galactose when GALT activity is impaired, contributing a large share to urinary galactitol and galactonate excretion. The ability of heart and muscle to form galactonate may also contribute to the G/G mouse's ability to slowly oxidize galactose to CO2, since the compound is an intermediate in an alternate route for galactose disposition.
在膳食半乳糖负荷条件下，缺乏1-磷酸半乳糖尿苷转移酶（GALT）的小鼠在心脏和骨骼肌中积累大量的半乳糖醇和半乳糖酸。与肝脏、大脑和肾脏不同，当GALT缺陷动物（G/G）摄入40%半乳糖饮食时，肝脏、大脑和肾脏几乎不形成半乳糖醇，而心脏和骨骼肌中的半乳糖醇分别达到22.90±1.62（平均值±标准误）和38.88±2.62微摩尔/克组织，其水平是1-磷酸半乳糖（Gal-1-P）的40-100倍。16日龄的哺乳G/G小鼠在心脏中积累半乳糖醇，在骨骼肌中积累较少。G/G小鼠的心 脏和骨骼肌也会形成半乳糖酸，其水平与肝脏相当，而肝脏以前被认为是在负荷条件下唯一能够将半乳糖转化为半乳糖酸的组织。数据表明，当GALT活性受损时，心脏和骨骼肌在半乳糖代谢中起作用，对尿中半乳糖醇和半乳糖酸的排泄有很大贡献。心脏和肌肉形成半乳糖酸的能力也可能有助于G/G小鼠将半乳糖缓慢氧化为二氧化碳的能力，因为该化合物是半乳糖代谢替代途径中的一个中间产物。
