Figure 1.

Oxalate transport in the intestine. (A) It is thought that the majority of oxalate is absorbed paracellularly. In states of fat malabsorption, increased fatty acids can bind calcium resulting in more oxalate ion free for absorption. Paracellular transporters to facilitate transcellular oxalate absorption include DRA (SLC26A3) on the apical surface that can exchange oxalate for bicarbonate, and SAT1 (SLC26A1) on the basolateral surface that can exchange oxalate for sulfate and other anions; (B) PAT1 (SLC26A6) in the apical surface can facilitate oxalate secretion into the lumen in exchange for chloride. SLC26A6 knockout mice are hyperoxaluric, presumably due to loss of this intestinal secretory pathway.