Plasma transport and tissue distribution of beta-carotene, vitamin A and retinol-binding protein in domestic cats.
The objective of this study was to determine retinol, retinyl esters and retinol-binding protein (RBP) as well as carotenoids in plasma, urine, liver and kidneys of randomly selected domestic cats. Retinol (240+/-64 ng/ml, mean+/-S.D.) represented one-third of total retinyl esters (736+/-460 ng/ml) in plasma. Retinyl esters were stearate, palmitate and oleate representing 61+/-6, 36+/-13 and 5+/-3% of total retinyl esters, respectively. In half of the cats, retinyl esters (22+/-21 ng/ml) were found in the urine. Vitamin A in the livers (4317+/-1956 microg/g) was significantly higher than in the kidney cortex and medulla (14.16+/-8.92 and 7.59+/-4.52 microg/g, respectively, both P<0.001). RBP was detected in the plasma but not in the urine. Immunoreactive RBP was observed in hepatocytes and in the cells of the proximal tubules. beta-Carotene was present in plasma but never in tissues. The results show that similar to canines differences in vitamin A metabolism in cats are related to the occurrence of retinyl esters in plasma. They differ, however, with regard to the tissue distribution of beta-carotene and the excretion of vitamin A in the urine.
Raila
J
J
Institute of Nutritional Science, University Potsdam, Arthur-Scheunert-Allee 114-116, D-14558 Potsdam-Rehbrücke, Germany. jraila@rz.uni.potsdam.de
Mathews
U
U
Schweigert
F J
FJ
D000818:Animals; D001692:Biological Transport; D002415:Cats; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D022781:Hepatocytes / Q000378:metabolism; D007074:Immunoglobulin G / Q000378:metabolism; D007150:Immunohistochemistry; D007668:Kidney / Q000378:metabolism; D007679:Kidney Medulla / Q000378:metabolism; D008099:Liver / Q000473:pathology; D008297:Male; D019301:Oleic Acid / Q000096:biosynthesis; D010168:Palmitates / Q000378:metabolism; D010949:Plasma / Q000378:metabolism*; D012177:Retinol-Binding Proteins / Q000096:biosynthesis*; D054839:Retinol-Binding Proteins, Plasma; D013228:Stearates / Q000378:metabolism; D014018:Tissue Distribution; D014801:Vitamin A / Q000096:biosynthesis* / Q000652:urine; D019207:beta Carotene / Q000096:biosynthesis*
D007074:Immunoglobulin G; D010168:Palmitates; D012177:Retinol-Binding Proteins; D054839:Retinol-Binding Proteins, Plasma; D013228:Stearates; D019207:beta Carotene; D014801:Vitamin A; D019301:Oleic Acid