TY - JOUR
T1 - The anion exchanger PAT-1 (Slc26a6) does not participate in oxalate or chloride transport by mouse large intestine
AU - Whittamore, Jonathan M.
AU - Hatch, Marguerite
N1 - Funding Information:
This work was supported by National Institutes of Health grants DK-108755 and DK-088892 to M. Hatch. J. Whittamore was also supported by a research grant from the Oxalosis & Hyperoxaluria Foundation.
Publisher Copyright:
© 2020, Springer-Verlag GmbH Germany, part of Springer Nature.
PY - 2021/1
Y1 - 2021/1
N2 - The membrane-bound transport proteins responsible for oxalate secretion across the large intestine remain unidentified. The apical chloride/bicarbonate (Cl−/HCO3−) exchanger encoded by Slc26a6, known as PAT-1 (putative anion transporter 1), is a potential candidate. In the small intestine, PAT-1 makes a major contribution to oxalate secretion but whether this role extends into the large intestine has not been directly tested. Using the PAT-1 knockout (KO) mouse, we compared the unidirectional absorptive (Jmsion) and secretory (Jsmion) flux of oxalate and Cl− across cecum, proximal colon, and distal colon from wild-type (WT) and KO mice in vitro. We also utilized the non-specific inhibitor DIDS (4,4′-diisothiocyano-2,2′-stilbenedisulfonic acid) to confirm a role for PAT-1 in WT large intestine and (in KO tissues) highlight any other apical anion exchangers involved. Under symmetrical, short-circuit conditions the cecum and proximal colon did not transport oxalate on a net basis, whereas the distal colon supported net secretion. We found no evidence for the participation of PAT-1, or indeed any other DIDS-sensitive transport mechanism, in oxalate or Cl− by the large intestine. Most unexpectedly, mucosal DIDS concurrently stimulated JmsOx and JsmOx by 25–68% across each segment without impacting net transport. For the colon, these changes were directly proportional to increased transepithelial conductance suggesting this response was the result of bidirectional paracellular flux. In conclusion, PAT-1 does not contribute to oxalate or Cl− transport by the large intestine, and we urge caution when using DIDS with mouse colonic epithelium.
AB - The membrane-bound transport proteins responsible for oxalate secretion across the large intestine remain unidentified. The apical chloride/bicarbonate (Cl−/HCO3−) exchanger encoded by Slc26a6, known as PAT-1 (putative anion transporter 1), is a potential candidate. In the small intestine, PAT-1 makes a major contribution to oxalate secretion but whether this role extends into the large intestine has not been directly tested. Using the PAT-1 knockout (KO) mouse, we compared the unidirectional absorptive (Jmsion) and secretory (Jsmion) flux of oxalate and Cl− across cecum, proximal colon, and distal colon from wild-type (WT) and KO mice in vitro. We also utilized the non-specific inhibitor DIDS (4,4′-diisothiocyano-2,2′-stilbenedisulfonic acid) to confirm a role for PAT-1 in WT large intestine and (in KO tissues) highlight any other apical anion exchangers involved. Under symmetrical, short-circuit conditions the cecum and proximal colon did not transport oxalate on a net basis, whereas the distal colon supported net secretion. We found no evidence for the participation of PAT-1, or indeed any other DIDS-sensitive transport mechanism, in oxalate or Cl− by the large intestine. Most unexpectedly, mucosal DIDS concurrently stimulated JmsOx and JsmOx by 25–68% across each segment without impacting net transport. For the colon, these changes were directly proportional to increased transepithelial conductance suggesting this response was the result of bidirectional paracellular flux. In conclusion, PAT-1 does not contribute to oxalate or Cl− transport by the large intestine, and we urge caution when using DIDS with mouse colonic epithelium.
KW - Dicarboxylic acid
KW - Radiotracer
KW - Solute carrier
KW - Ussing chamber
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U2 - 10.1007/s00424-020-02495-x
DO - 10.1007/s00424-020-02495-x
M3 - Article
C2 - 33205229
AN - SCOPUS:85096132409
SN - 0031-6768
VL - 473
SP - 95
EP - 106
JO - Pflugers Archiv European Journal of Physiology
JF - Pflugers Archiv European Journal of Physiology
IS - 1
ER -