Bode W, Mocking J A, van den Berg H
TNO-CIVO Toxicology and Nutrition Institute Zeist, Department of Clinical Biochemistry, The Netherlands.
J Nutr. 1991 Mar;121(3):318-29. doi: 10.1093/jn/121.3.318.
Vitamin B-6 vitamer distribution and activities of vitamin B-6 metabolizing enzymes were evaluated in aging male and female Wistar rats fed a purified diet (containing 250 g of casein and 6 mg of pyridoxine hydrochloride per kg) from weaning until 31 mo of age. Plasma pyridoxal 5'-phosphate (PLP) concentration became lower with increasing age, with the largest decrease in the 1st yr of life. An age-related change in vitamin B-6 distribution between the various tissues examined was observed: B-6 vitamer content increased in heart and brain, whereas PLP content decreased in gastrocnemius muscle, kidney and liver. The decrease in muscle PLP content occurred in concert with a decrease in muscle glycogen phosphorylase activity. Urinary 4-pyridoxic acid (4-PA) excretion increased with age, especially in female rats, in parallel with an increase in liver pyridoxal oxidase and pyridoxal dehydrogenase activities. Age-related changes in vitamin B-6 distribution were probably not causally related to changes in activity of vitamin B-6 metabolizing enzymes; they were regarded as consequences of changes in protein metabolism. The higher urinary 4-PA excretion in older rats may reflect a lower vitamin B-6 requirement; however, the lower PLP content of gastrocnemius muscle may indicate an age-related decrease in vitamin B-6 body stores.
在从断奶到31月龄期间喂食纯化日粮（每千克含250克酪蛋白和6毫克盐酸吡哆醇）的老年雄性和雌性Wistar大鼠中，评估了维生素B-6的维生素原分布以及维生素B-6代谢酶的活性。血浆磷酸吡哆醛（PLP）浓度随着年龄增长而降低，在生命的第1年下降幅度最大。在所检查的各种组织之间观察到维生素B-6分布的年龄相关变化：心脏和大脑中的维生素B-6维生素原含量增加，而腓肠肌、肾脏和肝脏中的PLP含量降低。肌肉PLP含量的降低与肌肉糖原磷酸化酶活性的降低同时发生。尿中4-吡哆酸（4-PA）排泄量随年龄增加，尤其是在雌性大鼠中，与肝脏吡哆醛氧化酶和吡哆醛脱氢酶活性的增加平行。维生素B-6分布的年龄相关变化可能与维生素B-6代谢酶活性的变化没有因果关系；它们被认为是蛋白质代谢变化的结果。老年大鼠中较高的尿4-PA排泄量可能反映较低的维生素B-6需求量；然而，腓肠肌中较低的PLP含量可能表明维生素B-6体内储存量随年龄减少。
