Influence of age and sex on vitamin B-6 vitamer distribution and on vitamin B-6 metabolizing enzymes in Wistar rats.
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.
Bode
W
W
TNO-CIVO Toxicology and Nutrition Institute Zeist, Department of Clinical Biochemistry, The Netherlands.
Mocking
J A
JA
van den Berg
H
H
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001835:Body Weight; D004032:Diet; D005260:Female; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D009929:Organ Size; D011732:Pyridoxal Phosphate / Q000097:blood; D011736:Pyridoxine / Q000378:metabolism* / Q000493:pharmacokinetics; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution
D011732:Pyridoxal Phosphate; D011736:Pyridoxine