Kayne L H, D'Argenio D Z, Meyer J H, Hu M S, Jamgotchian N, Lee D B
Medical Service, Veterans Affairs Medical Center, Sepulveda, California 91343.
J Clin Invest. 1993 Mar;91(3):915-22. doi: 10.1172/JCI116313.
Available information supports the dominance of the proximal intestine in inorganic phosphate (Pi) absorption. However, there is no strategy for analyzing segmental Pi absorption from a spontaneously propelled meal in an intact animal. We propose a solution using compartmental analysis. After intragastric administration of a 32P-labeled Pi liquid meal containing a nonabsorbable marker, [14C]polyethylene glycol (PEG), rats were killed at 2, 10, 20, 30, 60, 120, and 240 min. The gastrointestinal tract was removed and divided into seven segments, from which 32P and [14C]PEG were recovered. Data was expressed as a percentage of the dose fed, i.e., (32P[in segment] divided by 32P[fed]) and [14C]PEG[in segment] divided by [14C]PEG[fed]), respectively. A compartmental model was constructed and the rate constants for intersegmental transit and segmental absorption were estimated. The "goodness of fit" between the simulated model and the actual data indicates the estimated rate constants reflect in vivo events. The duodenum, with the highest transit and absorption rates, accounted for a third of the total absorption. However, the terminal ileum, with a lower absorption rate but a longer transit time, absorbed an equal amount of Pi. This approach allows the analysis of the mechanism and the regulation of Pi absorption under more authentic in vivo conditions.
现有信息支持近端肠道在无机磷酸盐（Pi）吸收中占主导地位。然而，目前尚无在完整动物中分析自发推进性食物各段Pi吸收情况的方法。我们提出一种使用房室分析的解决方案。在胃内给予含有不可吸收标记物[14C]聚乙二醇（PEG）的32P标记的Pi液体食物后，在2、10、20、30、60、120和240分钟处死大鼠。取出胃肠道并分为七个节段，从中回收32P和[14C]PEG。数据分别表示为喂食剂量的百分比，即（节段内的32P除以喂食的32P）和（节段内的[14C]PEG除以喂食的[14C]PEG）。构建房室模型并估计节段间转运和节段吸收的速率常数。模拟模型与实际数据之间的“拟合优度”表明估计的速率常数反映了体内事件。十二指肠的转运和吸收率最高，占总吸收量的三分之一。然而，回肠末端的吸收率较低但转运时间较长，吸收的Pi量相同。这种方法可以在更真实的体内条件下分析Pi吸收的机制和调节。
