[Recent findings on the importance of vitamin A and its metabolism in man and laboratory animals].
A survey is given concerning recent realizations of importance and metabolism of vitamin A in man and experimental animals. The transport of vitamin A from the small intestine takes place in form of esters by inclusion in chylomicrons and lipoproteins. A higher content in the blood plasma over a longer period evokes toxic effects. In the liver one part of the vitamin A in form of an ester with binding to lipoproteins is accumulated, one part is - according to the need - associated with a vitamin-A-binding protein, which forms complexes with prealbumin molecules and transports the vitamin to the various places of effect. With the help of the receptor proteins the vitamin A is included in the cells, in which it is effective and is transported into the vitamin-A-aldehyde and the vitamin-A-acid. The vitamin A and the vitamin-A-acid are transported into the cell nuclei with the help of receptor-proteins and play a role in the differentiation of the tissues and in the regulation of the synthesis of RNA. When a deficit or an abundance of vitamin A is present in the early phase of pregnancy malformations in the fetuses appear. The vitamin A and structure-similar connections have an inhibiting effect on the development of tumours.
D000818:Animals; D001692:Biological Transport; D001717:Birds; D002338:Carotenoids / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002914:Chylomicrons / Q000378:metabolism; D000013:Congenital Abnormalities / Q000209:etiology; D005260:Female; D005399:Fishes; D006801:Humans; D008074:Lipoproteins / Q000378:metabolism; D008175:Lung Neoplasms / Q000378:metabolism; D008297:Male; D008322:Mammals; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012313:RNA / Q000096:biosynthesis; D012172:Retinaldehyde / Q000378:metabolism; D012907:Smoking; D014212:Tretinoin / Q000378:metabolism; D014801:Vitamin A / Q000378:metabolism*; D014802:Vitamin A Deficiency / Q000150:complications
D002352:Carrier Proteins; D002914:Chylomicrons; D008074:Lipoproteins; D014801:Vitamin A; D002338:Carotenoids; D014212:Tretinoin; D012313:RNA; D012172:Retinaldehyde
Neuere Erkenntnisse zur Bedeutung und zum Stoffwechsel des vitamin A beim Menschen und bei Versuchstieren.