Cortisol Absorption in Man

Absorption of cortisol from Ringer's solution in the normal human small gut was characterized by a distally decreasing gradient. This defines a membrane gradient in terms of this lipophilic-hydrophilic molecule. Glucose in the Ringer's increased cortisol absorption uniformly throughout the small gut, but the gradient was maintained. It is hypothesized that this is a specific metabolic effect of high glucose concentration on mucosal cells throughout the small gut. It was concentration dependent, and was detected in the earliest measurements we could make, continued throughout glucose perfusion, and persisted for about 2 hours after glucose was stopped. Net water absorption from the gut was higher with glucose-Ringer's than with Ringer's and showed a gradient. The glucoseinduced increase in water absorption was chiefly in the upper small gut (< 200 cm.), in contrast to the uniform increase in cortisol absorption throughout the small gut. Although glucose increases cortisol and water absorption in the upper small gut these processes seem to be unrelated because: (1) in the lower small gut glucose increases cortisol absorption, whereas net water absorption is unchanged or decreasing; (2) the net water absorption gradient from Ringer's is the reverse of that for cortisol: there is net secretion of fluid into the gut where cortisol absorption is high, and net absorption from the gut where cortisol absorption is low. In patients with small gut malabsorption, cortisol and net water absorption rates were reduced, and in some cases their gradients were reversed.

正常人小肠对林格氏液中皮质醇的吸收呈现远端递减梯度的特征。这从这种亲脂 - 亲水分子的角度确定了一种膜梯度。林格氏液中的葡萄糖使整个小肠对皮质醇的吸收均匀增加，但梯度得以维持。据推测，这是高浓度葡萄糖对整个小肠黏膜细胞的一种特定代谢作用。它具有浓度依赖性，在我们能够进行的最早测量中就被检测到，在整个葡萄糖灌注过程中持续存在，并且在停止灌注葡萄糖后持续约2小时。 肠道对含葡萄糖的林格氏液的净水吸收量高于单纯的林格氏液，并且呈现梯度。葡萄糖诱导的水吸收增加主要发生在小肠上部（<200厘米），这与皮质醇在整个小肠均匀吸收增加形成对比。尽管葡萄糖增加了小肠上部皮质醇和水的吸收，但这些过程似乎并无关联，因为：（1）在小肠下部，葡萄糖增加皮质醇吸收，而净水吸收不变或减少；（2）林格氏液的净水吸收梯度与皮质醇的相反：在皮质醇吸收高的部位，液体净分泌进入肠道，而在皮质醇吸收低的部位，液体净吸收自肠道。 在小肠吸收不良的患者中，皮质醇和净水吸收率降低，在某些情况下，它们的梯度发生逆转。