Tanumihardjo S A, Olson J A
Department of Biochemistry and Biophysics, Iowa State University, Ames 50011.
J Nutr. 1988 May;118(5):598-603. doi: 10.1093/jn/118.5.598.
3,4-Didehydroretinol (vitamin A2, DR, dehydroretinol), a naturally occurring analogue of retinol (vitamin A1, R), is active in vision, growth and cellular differentiation but is converted to retinol in very small amounts, if at all. When vitamin A-depleted rats were given 500 micrograms of R acetate, a naturally occurring mixture of 480 micrograms DR ester and 20 micrograms R ester or 500 micrograms DR acetate orally in corn oil, serum levels of all administered retinoids peaked between 3.5 and 5 h and then declined. When an oral dose of 600 micrograms DR/kg body wt was administered to rats with various liver reserves of vitamin A, the serum ratio of DR to R at 3.5 h was inversely related to the liver reserves of vitamin A below approximately 2 micrograms/g liver. Because the administration of DR does not affect serum R values, a single blood sample taken at 3.5 h might provide information analogous to that obtained from two blood samples in the conventional relative dose-response method.
3,4-二脱氢视黄醇（维生素A2，DR，脱氢视黄醇）是视黄醇（维生素A1，R）的一种天然存在的类似物，在视觉、生长和细胞分化中具有活性，但即使有，也仅有极少量会转化为视黄醇。当给维生素A缺乏的大鼠口服500微克醋酸视黄醇、480微克DR酯和20微克R酯的天然混合物或500微克醋酸DR（溶于玉米油）时，所有给药类视黄醇的血清水平在3.5至5小时达到峰值，然后下降。当给具有不同肝脏维生素A储备的大鼠口服600微克DR/千克体重时，3.5小时时血清中DR与R的比值与肝脏维生素A储备呈负相关，肝脏维生素A储备低于约2微克/克肝脏。由于给予DR不影响血清R值，在3.5小时采集的单一血样可能提供与传统相对剂量反应法中从两份血样获得的信息类似的信息。
