Na(+)-coupled Cl- transport in the gastric mucosa of the guinea pig.
The Cl-/HCO3 exchange mechanism usually postulated to occur in gastric mucosa cannot account for the Na(+)-dependent electrogenic serosal to mucosal Cl- transport often observed. It was recently suggested that an additional Cl- transport mechanism driven by the Na+ electrochemical potential gradient may be present on the serosal side of the tissue. To verify this, we have studied Cl- transport in guinea pig gastric mucosa. Inhibiting the (Na+, K+) ATPase either by serosal addition of ouabain or by establishing K(+)-free mucosal and serosal conditions abolished net Cl- transport. Depolarizing the cell membrane potential with triphenylmethylphosphonium (a lipid-soluble cation), and hence reducing both the Na+ and Cl- electrochemical potential gradients, resulted in inhibition of net Cl- flux. Reduction of short-circuit current on replacing Na+ by choline in the serosal bathing solution was shown to be due to inhibition of Cl- transport. Serosal addition of diisothiocyanodisulfonic acid stilbene (an inhibitor of anion transport systems) abolished net Cl- flux but not net Na+ flux. These results are compatible with the proposed model of a Cl-/Na+ cotransport mechanism governing serosal Cl- entry into the secreting cells. We suggest that the same mechanism may well facilitate both coupled Cl-/Na+ entry and coupled HCO3-/Na+ exit on the serosal side of the tissue.
Klemperer
G
G
Department of Membrane Research, The Weizmann Institute of Science, Rehovot, Israel.
Lelchuk
S
S
Caplan
S R
SR
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D017136:Ion Transport / Q000187:drug effects; D008954:Models, Biological; D009861:Onium Compounds / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D014320:Triphenylmethyl Compounds / Q000494:pharmacology
D001639:Bicarbonates; D002712:Chlorides; D004791:Enzyme Inhibitors; D009861:Onium Compounds; D014320:Triphenylmethyl Compounds; C011561:triphenylmethylphosphonium; D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D011188:Potassium