Bikhazi A B, Hasbini A S
Department of Physiology, American University of Beirut, Lebanon.
J Pharm Sci. 1989 Jan;78(1):17-20. doi: 10.1002/jps.2600780106.
An intestinal perfusion technique is reported for the study of the differential absorption of vitamin D3 and its active metabolite, 1,25-dihydroxyvitamin D3, through intact jejunal segments of rats. Samples of introduced and collected perfusates, intestinal homogenates, and portal blood were assayed for [14C]vitamin D3 or [3H]1 alpha,25-dihydroxyvitamin D3 content at specified time intervals in control rats and in rats injected ip with cycloheximide (3 mg/kg body weight). Vitamin D3 uptake from the perfusates in cycloheximide-treated groups did not differ from controls. However, an approximately 2-fold increase of vitamin D3 retention in the perfused intestinal segments was observed after cycloheximide treatment. A 0.25-fold decrease was observed in the uptake of 1,25-dihydroxyvitamin D3 from the perfusates after cycloheximide treatment, and an approximately 2.5-fold increase in its intestinal retention was noted. An increase in the active metabolite concentration was observed in the portal venous system 75 min after initiation of perfusion, with no detectable amounts being recorded prior to the first hour. The results suggest that intracellular binding proteins may be involved in the transport of labeled vitamin D3 and labeled 1,25-dihydroxyvitamin D3 through rat enterocytes. Furthermore, vitamin D3 may have been more readily channeled through an esterification process than 1,25-dihydroxyvitamin D3 prior to their appearance in the portal venous system.
本文报道了一种肠道灌注技术，用于研究维生素D3及其活性代谢物1,25 - 二羟基维生素D3通过大鼠完整空肠段的差异吸收情况。在特定时间间隔内，对对照组大鼠以及腹腔注射环己酰亚胺（3 mg/kg体重）的大鼠的灌注液、肠道匀浆和门静脉血样本进行检测，分析其中[14C]维生素D3或[3H]1α,25 - 二羟基维生素D3的含量。环己酰亚胺处理组从灌注液中摄取维生素D3的情况与对照组无差异。然而，环己酰亚胺处理后，观察到灌注肠段中维生素D3的保留量增加了约2倍。环己酰亚胺处理后，从灌注液中摄取1,25 - 二羟基维生素D3的量减少了0.25倍，其在肠道中的保留量增加了约2.5倍。灌注开始75分钟后，门静脉系统中活性代谢物浓度增加，在第一小时之前未检测到可测量的量。结果表明，细胞内结合蛋白可能参与了标记的维生素D3和标记的1,25 - 二羟基维生素D3通过大鼠肠细胞的转运过程。此外，在维生素D3和1,25 - 二羟基维生素D3出现在门静脉系统之前，维生素D3可能比1,25 - 二羟基维生素D3更容易通过酯化过程进行转运。
