닭에 過量給與한 vitamin A의 血中循環에 關한 硏究

Effect of excess feeding of vitamin A on the blood circulation of vitamin A in chicks

Effects of an excess feeding of vitamin A, in chicks, on the blood concentration and the circulating forms of vitamin A and it’s related compounds were studied. A number of 32 chicks, 7 week old, were fed for 27 days on vitamin A free diet in which 19.94mg of carotenoid were contained per kg of diet. And the vitamin A depleted chicks were divided into 4 groups each of which comprised 8 chicks. The 4 groups chicks were fed with 4 different vitamin A supplemented diets, namely, 10,000, 100,000, 500,000 and 1,000,000 I.U. per kg diet, respectively. Feeding the vitamin A supplemented diet was continued to 27 days when the chicks showed a fairly constant and elevated level of plasma vitamin A. Form such chicks, blood samples were collected by heart puncture and harvested blood plasma in an oxalated state. Following the plasma sampling, livers were colleted and flushed with saline solution and weighed. The blood plasma and liver samples were stored at -20℃ until to use. Throughout the studies the following experimental results were obtained and summarized as follows: 1. The administration of excessive doses of vitamin A resulted in decreases of plasma carotenoid levels, in the ranges of 58.8, 21.2 and 15.4 per cent in 100,000 500,000, and 1,000,000 I.U. vitamin A per kg of diet, respectively. 2. Excessive doses of 100,000, 500,000 and 1,000,000 I.U. of vitamin A per kg of diet also resulted in elevations of plasma vitamin A levels, to 138.73mcg, 287.4mcg and 293.79mcg per 100ml blood plasma, respectively. 3. Increasing plasma vitamin A and decreasing plasma carotenoid, which possibly expressed their correlation factor of -0.776 and regression equation by y=1,272-3.594x may suggest that the excess feeding and increasing plasma concentration of vitamin A may inhibit the absorption of carotenoid from intestine. 4. The increased levels of plasma vitamin A in 1,000,000 I.U. chicks were mainly due to large increases of retinyl ester (406 per cent) and on the other hand, a slight increases, 41 per cent, of retinol was observed. 5. Dense correlation was maintained between plasma concentration and liver storage of vitamin A levels and this may be presumed from vitamin A content of liver by regression equation, y=115+38x.