The adenosine A(2B) receptor is involved in anion secretion in human pancreatic duct Capan-1 epithelial cells

Adenosine modulates a wide variety of biological processes via adenosine receptors. In the exocrine pancreas, adenosine regulates transepithelial anion secretion in duct cells and is considered to play a role in acini-to-duct signaling. To identify the functional adenosine receptors and Cl(−) channels important for anion secretion, we herein performed experiments on Capan-1, a human pancreatic duct cell line, using open-circuit Ussing chamber and gramicidin-perforated patch-clamp techniques. The luminal addition of adenosine increased the negative transepithelial potential difference (V(te)) in Capan-1 monolayers with a half-maximal effective concentration value of approximately 10 μM, which corresponded to the value obtained on whole-cell Cl(−) currents in Capan-1 single cells. The effects of adenosine on V(te), an equivalent short-circuit current (I(sc)), and whole-cell Cl(−) currents were inhibited by CFTRinh-172, a cystic fibrosis transmembrane conductance regulator (CFTR) Cl(−) channel inhibitor. The adenosine A(2B) receptor agonist, BAY 60-6583, increased I(sc) and whole-cell Cl(−) currents through CFTR Cl(−) channels, whereas the A(2A) receptor agonist, CGS 21680, had negligible effects. The A(2B) receptor antagonist, PSB 603, inhibited the response of I(sc) to adenosine. Immunohistochemical analysis showed that the A(2A) and A(2B) receptors colocalized with Ezrin in the luminal membranes of Capan-1 monolayers and in rat pancreatic ducts. Adenosine elicited the whole-cell Cl(−) currents in guinea pig duct cells. These results demonstrate that luminal adenosine regulates anion secretion by activating CFTR Cl(−) channels via adenosine A(2B) receptors on the luminal membranes of Capan-1 cells. The present study endorses that purinergic signaling is important in the regulation of pancreatic secretion.