Secretion of H+ and K+ by bullfrog gastric mucosa: characterization of K+ transport pathway.
The transport of K+ and H+ (both expressed as mueq/h) by in vitro chambered bullfrog (Rana catesbeiana) gastric mucosa have been studied under a variety of conditions such as anoxia, addition of p-chloromercuribenzene sulfonic acid (PCMBS) into the secretory solution, inclusion of ouabain in the nutrient solution, addition of thiocyanate (SCN-) into the mucosal solution, and replacement of nutrient chloride (Cl-) with sulfate (SO4(2-)), or gluconate (Gl). Anoxia reversibly reduced the H+ transport close to zero within 15 min and gradually reduces the K+ transport throughout the 2-h period of anoxia. The presence of 2.5 X 10(-4) M mucosal PCMBS in the histamine-stimulated mucosa increases the K+ transport, which is promptly reduced by changing the gas phase to 95% N2-5% CO2. Addition of ouabain to the nutrient solution of the histamine-stimulated mucosa with PCMBS on the mucosal side significantly (P < 0.05) reduces the K+ transport within 60 min. Addition of SCN- to the mucosal solution of a histamine-stimulated mucosa with regular nutrient or O, K+ nutrient and 10, K+ mucosal solution reduces the H+ transport to near zero within 60 min. This SCN- inhibition can be reversed by elevating secretory K+. Substitution of nutrient Cl- with SO4(2-) or Gl in the histamine-stimulated mucosa reversibly inhibits H+ transport and reduces K+ transport to a low level (0.7 +/- 0.05). Our data suggest that the K+ transport across the apical membranes of gastric cells is to a large extent a passive carrier-mediated process, and the transport of both K+ and Cl- are coupled at the apical membrane.
D002731:4-Chloromercuribenzenesulfonate / Q000494:pharmacology; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D004734:Energy Metabolism; D005744:Gastric Acid / Q000378:metabolism*; D005753:Gastric Mucosa / Q000378:metabolism*; D005942:Gluconates / Q000494:pharmacology; D006632:Histamine / Q000494:pharmacology; D000860:Hypoxia / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D011892:Rana catesbeiana
D002352:Carrier Proteins; D002712:Chlorides; D005942:Gluconates; D002731:4-Chloromercuribenzenesulfonate; D006632:Histamine; D011188:Potassium