P2Y(11), a purinergic receptor acting via cAMP, mediates secretion by pancreatic duct epithelial cells.
Pancreatic duct epithelial cells (PDEC) mediate the exocrine secretion of fluid and electrolytes. We previously reported that ATP and UTP interact with P2Y(2) receptors on nontransformed canine PDEC to increase intracellular free Ca2+ concentration ([Ca2+](i)) and stimulate Ca2+-activated Cl- and K+ channels. We now report that ATP interacts with additional purinergic receptors to increase cAMP and activate Cl- channels. ATP, 2-methylthio-ATP, and ATP-gamma-S stimulated a 4- to 10-fold cAMP increase with EC(50) of 10-100 microM. Neither UTP nor adenosine stimulated a cAMP increase, excluding a role for P2Y(2) or P1 receptors. Although UTP stimulated an (125)I(-) efflux that was fully inhibited by 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl) ester (BAPTA-AM), ATP stimulated a partially resistant efflux, suggesting activation of additional Cl- conductances through P2Y(2)-independent and Ca2+-independent pathways. In Ussing chambers, increased cAMP stimulated a much larger short-circuit current (I(sc)) increase from basolaterally permeabilized PDEC monolayers than increased [Ca2+](i). Luminal ATP and UTP and serosal UTP stimulated a small Ca2+-type I(sc) increase, whereas serosal ATP stimulated a large cAMP-type I(sc) response. Serosal ATP effect was inhibited by P2 receptor blockers and unaffected by BAPTA-AM, supporting ATP activation of Cl- conductances through P2 receptors and a Ca2+-independent pathway. RT-PCR confirmed the presence of P2Y(11) receptor mRNA, the only P2Y receptor acting via cAMP.
Nguyen
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Department of Medicine, Division of Gastroenterology, University of Washington and Department of Veterans Affairs Puget Sound Health Care System, Seattle, WA 98108, USA. t1nguyen@u.washington.edu
Meichle
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Kim
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Wong
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Moody
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D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000502:physiology; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D002712:Chlorides / Q000378:metabolism; D000242:Cyclic AMP / Q000502:physiology*; D004285:Dogs; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007454:Iodides / Q000378:metabolism*; D007457:Iodine Radioisotopes; D007700:Kinetics; D008969:Molecular Sequence Data; D010183:Pancreatic Ducts / Q000502:physiology*; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D015220:Calcium Channels; D002614:Chelating Agents; D002712:Chlorides; D007454:Iodides; D007457:Iodine Radioisotopes; C109734:P2RY11 protein, human; D018048:Receptors, Purinergic P2; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D002118:Calcium