Vitamin A in the urine of carnivores.
Vitamin A levels (retinol equivalents) in the urine of canines were between 423 ng/ml (dog) and 6304 ng/ml (silver fox). Neither vitamin A nor vitamin E was found in the urine of herbivores, omnivorous and rodents. No vitamin A but low levels of vitamin E were detected in cats. Vitamin A in the urine was present as retinol and retinyl esters (basically retinyl palmitate/oleate). The total excretion of vitamin A represented 15 to 63% of the daily uptake in dogs, while less than 4% of vitamin E was excreted. Results after precipitation and ultracentrifugation indicate that similar carrier proteins may exist for retinol, retinyl esters and alpha-tocopherol in the urine. The biological significance of this phenomenon is discussed with regard to the high concentrations of retinyl esters in the blood plasma of carnivores bound to lipoproteins.
Institute of Physiology, Physiological Chemistry and Nutrition Physiology, Veterinary Faculty, Ludwig-Maximilians-Universität München, West Germany.
F J
FJ
Schweigert
E
E
Thomann
H
H
Zucker
D000818:Animals; D002415:Cats; D002417:Cattle; D004285:Dogs; D005260:Female; D005589:Foxes; D006736:Horses; D008074:Lipoproteins / Q000097:blood; D008297:Male; D008657:Metabolic Clearance Rate; D046048:Seals, Earless; D012756:Sheep; D013552:Swine; D014801:Vitamin A / Q000652:urine*; D014810:Vitamin E / Q000652:urine
D008074:Lipoproteins; D014801:Vitamin A; D014810:Vitamin E