Effects of zinc and vitamin A deficient diets on the hepatic mobilization and urinary excretion of vitamin A in rats.
Weanling rats were fed diets deficient in zinc (ZD), vitamin A (AD), or both (ZAD) for 3 weeks. Each then received 20 mug of 11,12-3H-retinyl acetate. Plasma retinol was monitored for radioactivity for 5 hours and urine for 6 days. Rats were killed and measurements made of plasma and liver vitamin A and plasma zinc. Plasma vitamin A was depressed but growth was not affected in AD rats compared to pair-fed controls. Radioactivity appeared most rapidly in the plasma retinol fractions of the two vitamin A-depleted groups (AD and ZAD) and was excreted most rapidly in the urine of these same groups. Zinc-deficient diets (ZD and ZAD) caused depressed plasma levels of zinc and vitamin A and growth retardation greater than in pair-fed controls. However zinc deficiency had no effect on mobilization of newly-ingested vitamin A or urinary excretion of labeled metabolites. Liver stores of vitamin A were lower for ZD rats than for controls. The data indicate that zinc deficiency is not a limiting factor in hepatic vitamin A release except as it influences growth and body demand for the vitamin. The data also suggest that newly-absorbed vitamin A is mobilized and utilized in preference to that previously stored in the liver.
D000818:Animals; D008099:Liver / Q000033:anatomy & histology / Q000378:metabolism*; D008297:Male; D009929:Organ Size; D051381:Rats; D014801:Vitamin A / Q000378:metabolism* / Q000652:urine; D014802:Vitamin A Deficiency / Q000150:complications / Q000378:metabolism*; D015032:Zinc / Q000172:deficiency* / Q000378:metabolism
D014801:Vitamin A; D015032:Zinc