Furusho T, Wada M, Yasuhara T, Kataoka E, Kato S, Masushige S
Department of Nutrition, Junior College of Agriculture, Tokyo University of Agriculture, Japan.
Int J Vitam Nutr Res. 1998;68(5):287-92.
The effect of dietary protein levels on tissue-specific distribution and metabolism of vitamin A was studied in rats given [15-14C] retinol (14C-ROH). The weanling rats were fed a low level vitamin A diet for 10 days, then rats (15 rats per group) were divided into 2 groups; one was given a 40% casein diet as a high protein diet (HP-diet), and the other a 5% casein diet as a low protein diet (LP-diet). After 10 days feeding on these diets, 14C-ROH (5 microCi/rat) was given to both groups, HP-diet and LP-diet, by intraperitoneal injection. The radioactivity in the exhalated gases, urine and feces was measured to estimate the rate of vitamin A metabolism. The tissue specific-distribution of ROH was studied in terms of the radioactivities of the ROH fractions separated by HPLC. The hepatic 14C-ROH content in the HP-diet group was lower than that in the LP-diet group at 24, 48, and 72 hours after administration of 14C-ROH. In contrast, 14C-ROH content in serum, spleen, pancreas, and small intestinal mucosa in the HP-diet group was higher than that in the LP-diet group. The radioactivity of the exhalated gas and feces was higher in the HP-diet group. These results suggest that metabolism of vitamin A is higher with intake of a HP-diet. Thus, dietary protein levels may affect tissue-specific distribution and metabolism of vitamin A, thereby modulating the actions of this vitamin.
在给予[15-14C]视黄醇（14C-ROH）的大鼠中，研究了膳食蛋白质水平对维生素A组织特异性分布和代谢的影响。将断奶大鼠用低水平维生素A饮食喂养10天，然后将大鼠（每组15只）分为2组；一组给予40%酪蛋白饮食作为高蛋白饮食（HP饮食），另一组给予5%酪蛋白饮食作为低蛋白饮食（LP饮食）。在这些饮食喂养10天后，通过腹腔注射向HP饮食组和LP饮食组的两组大鼠给予14C-ROH（5微居里/只大鼠）。测量呼出气体、尿液和粪便中的放射性，以估计维生素A的代谢率。根据通过高效液相色谱法分离的ROH组分的放射性，研究了ROH的组织特异性分布。在给予14C-ROH后24、48和72小时，HP饮食组的肝脏14C-ROH含量低于LP饮食组。相反，HP饮食组血清、脾脏、胰腺和小肠黏膜中的14C-ROH含量高于LP饮食组。HP饮食组呼出气体和粪便的放射性较高。这些结果表明，摄入HP饮食时维生素A的代谢更高。因此，膳食蛋白质水平可能影响维生素A的组织特异性分布和代谢，从而调节该维生素的作用。
