Protein kinase C mediates the inhibitory effect of substance P on HCO3- secretion from guinea pig pancreatic ducts.
The inhibitory control of pancreatic ductal HCO(3)(-) secretion may be physiologically important in terms of limiting the hydrostatic pressure developed within the ducts and in terms of switching off pancreatic secretion after a meal. Substance P (SP) inhibits secretin-stimulated HCO(3)(-) secretion by modulating a Cl(-)-dependent HCO(3)(-) efflux step at the apical membrane of the duct cell (Hegyi P, Gray MA, and Argent BE. Am J Physiol Cell Physiol 285: C268-C276, 2003). In the present study, we have shown that SP is present in periductal nerves within the guinea pig pancreas, that PKC mediates the effect of SP, and that SP inhibits an anion exchanger on the luminal membrane of the duct cell. Secretin (10 nM) stimulated HCO(3)(-) secretion by sealed, nonperfused, ducts about threefold, and this effect was totally inhibited by SP (20 nM). Phorbol 12,13-dibutyrate (PDBu; 100 nM), an activator of PKC, reduced basal HCO(3)(-) secretion by approximately 40% and totally blocked secretin-stimulated secretion. In addition, bisindolylmaleimide I (1 nM to 1 microM), an inhibitor of PKC, relieved the inhibitory effect of SP on secretin-stimulated HCO(3)(-) secretion and also reversed the inhibitory effect of PDBu. Western blot analysis revealed that guinea pig pancreatic ducts express the alpha-, beta(I)-, delta-, epsilon-, eta-, theta-, zeta-, and mu-isoforms of PKC. In microperfused ducts, luminal H(2)DIDS (0.5 mM) caused intracellular pH to alkalinize and, like SP, inhibited basal and secretin-stimulated HCO(3)(-) secretion. SP did not inhibit secretion further when H(2)DIDS was present in the lumen, suggesting that SP and H(2)DIDS both inhibit the activity of an anion exchanger on the luminal membrane of the duct cell.
Hegyi
Péter
P
Institute for Cell and Molecular Biosciences, Univ. of Newcastle Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, United Kingdom.
Rakonczay
Zoltán
Z
Tiszlavicz
László
L
Varró
András
A
Tóth
András
A
Rácz
Gábor
G
Varga
Gábor
G
Gray
Michael A
MA
Argent
Barry E
BE
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006168:Guinea Pigs; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D008301:Maleimides / Q000494:pharmacology; D010183:Pancreatic Ducts / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D010477:Perfusion / Q000379:methods; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012633:Secretin / Q000494:pharmacology*; D017693:Sodium Bicarbonate / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism* / Q000494:pharmacology
D004791:Enzyme Inhibitors; D007211:Indoles; D007527:Isoenzymes; D008301:Maleimides; D012633:Secretin; D013373:Substance P; D015240:Phorbol 12,13-Dibutyrate; C018564:dihydro-DIDS; D017693:Sodium Bicarbonate; D011493:Protein Kinase C; C070515:bisindolylmaleimide I; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid