title: Na/H exchange at the apical membrane of guinea-pig gallbladder epithelium: properties and inhibition by cyclic AMP.
abstract: The properties and, in particular, the cAMP-sensitivity of apical Na/H exchange in guinea-pig gallbladder epithelium were investigated using gravimetric, pH-stat, and microelectrode techniques. Proton secretion was Na-dependent, inhibited by ouabain and amiloride, and insensitive to changes in apical membrane potential. It was markedly reduced by 8-Br-cAMP and PGE1. PGE1 also attenuated the changes in intracellular Na activity produced by luminal Na removal and restoration. Our results suggest inhibition of Na/H exchange by cAMP. In conjunction with the cAMP-induced rise in apical membrane Cl permeability shown previously, this effect can account for inhibition of NaCl absorption by cAMP.
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology*; D000527:Alprostadil / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D000242:Cyclic AMP / Q000502:physiology*; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D005704:Gallbladder / Q000378:metabolism*; D006168:Guinea Pigs; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D012964:Sodium / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers
chemical_list: D002352:Carrier Proteins; D017923:Sodium-Hydrogen Exchangers; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000584:Amiloride; D012964:Sodium; D000242:Cyclic AMP; D000527:Alprostadil