title: Effects of cyclic AMP, ouabain and furosemide on ion transport in isolated canine gastric mucosa.
abstract: 1. Cyclic AMP (10 mM), present in the serosal solution of isolated dog gastric mucosa, increased potential difference (p.d.), short-circuit current (ISC), net flux of Na+ from the mucosal to serosal side, and the unidirectional flux of K+ from the mucosal to serosal side. Cyclic AMP did not stimulate H+ or Cl- secretion. 2. Dibutyryl cyclic AMP (DBcAMP, 1 mM) or theophylline (2 mM), present in the serosal solution, stimulated H+ and Cl- secretion, decreased p.d., ISC and electrical resistance. These compounds had no effect on Na+ transport. The stimulatory effect of DBcAMP on H+ secretion was still present after pretreatment with cimetidine or atropine. 3. Ouabain abolished both the p.d. and ISC of the histamine-stimulated gastric mucosa. The mucosal to serosal flux of Na+ and the serosal to mucosal flux of Cl- were significantly decreased in the presence of ouabain. Ouabain caused an increase in the serosal to mucosal flux of K+ and high concentrations caused a significant reduction in H+ secretion. 4. Furosemide (10(-4) M) decreased p.d., ISC and net flux of Na+. Higher concentrations inhibited the net flux of Cl- from the serosal to mucosal side. 5. These results suggest that in isolated dog gastric mucosa, (1) both DBcAMP and theophylline may increase intracellular cyclic AMP to stimulate H+ and Cl- secretion, (2) cyclic AMP, outside the serosal membrane, stimulates active transport of Na+; in contrast, ouabain inhibits this active process predominantly, (3) the selective action of furosemide on Na+ transport indicates that Na+ and Cl- move via separate transport pathways across the serosal border.
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D003994:Bucladesine / Q000494:pharmacology; D002712:Chlorides / Q000378:metabolism; D000242:Cyclic AMP / Q000494:pharmacology*; D004285:Dogs; D005665:Furosemide / Q000494:pharmacology*; D005753:Gastric Mucosa / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D010042:Ouabain / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D013806:Theophylline / Q000494:pharmacology
chemical_list: D002712:Chlorides; D010042:Ouabain; D003994:Bucladesine; D005665:Furosemide; D012964:Sodium; D013806:Theophylline; D000242:Cyclic AMP; D011188:Potassium