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. 2015 Sep 15;309(6):C350–C360. doi: 10.1152/ajpcell.00191.2015

Fig. 3.

Fig. 3.

Oxygen homeostasis and physiologic regulation of intestinal epithelial function. In addition to the influence of countercurrent blood flow (see Fig. 1), microbial-derived short-chain fatty acids (e.g., butyrate) stimulate epithelial metabolism and deplete intracellular oxygen to the extent that hypoxia-inducible factor (HIF) 1 is stabilized. Transcriptional HIF responses in the normal colon include the physiologic regulation of genes important for butyrate transport [monocarboxylate transporter 1 (MCT1)], xenobiotic clearance (P-glycoprotein), adenosine metabolism (CD39 and CD73), epithelial barrier function [MUC3, intestinal trefoil factor (ITF), and claudin (CLDN1)], energy metabolism [creatine kinase enzymes (CKM/CKB) and SLC6A8], antimicrobial defense (hBD1), and iron absorption [divalent metal transporter 1 (DMT1), ferroportin, and hepcidin]. TJ, tight junction; AJ, adherens junction.