Pflügers Archiv

, Volume 428, Issue 5–6, pp 648–654 | Cite as

Model of bicarbonate secretion by resting frog stomach fundus mucosa I. Transepithelial measurements

  • Silvana Curci
  • Lucantonio Debellis
  • Rossella Caroppo
  • Eberhard Frömter
Transport Processes, Metabolism and Endocrinology; Kidney Gastrointestinal Tract, and Exocrine Glands


In the present in vitro experiments on gastric fundus mucosa of Rana esculenta we try to define the mechanism of alkaline secretion that is observed in summer frogs in the resting stomach (blockage of HCl secretion by ranitidine, 10−5 mol/l). The transepithelial voltage and the rate of alkalinization (ASR) of an unbuffered gastric lumen perfusate was measured as a function of serosal (and mucosal) fluid composition. ASR was high (0.88±S.E. 0.09 μEq·cm−2·h−1, n=11) during serosal bath perfusion with HCO3-Ringer solution, decreased slightly to 0.50±0.07 μEq·cm−2·h−1 (n=6) in HCO3-free HEPES-buffered Ringer solution of the same pH, and decreased to approximately 20% when carbonic anhydrase was inhibited by acetazolamide. While replacement of mucosal or serosal Cl did not — within 1 h — significantly alter ASR, replacement of serosal Na+ in the presence or absence of HCO3 strongly reduced ASR, and a similar reduction was observed after serosal application of the anion transport inhibitor DIDS (4,4-diisomiocyanatostilbene-2,2-disulphonate, 2·10−4 mol/l), the metabolic poison rotenone (10−5 mol/l), the uncoupler dinitrophenol (10−4 mol/l), and the Na+ pump inhibitor ouabain (10−4 mol/l), while serosal amiloride (10−4 mol/l) had no effect. These data can be accounted for by a model of alkaline secretion that consists of basolateral HCO3 uptake from the serosal fluid into the cell via a DIDS-inhibitable Na+(HCO3)n-cotransporter and HCO3 secretion from the cell to the gastric lumen via an anionic conductance pathway. Microelectrode experiments on oxyntopeptic cells reported in the subsequent paper suggest that these cells may also be involved in the resting state alkaline secretion.

Key words

Gastric fundus mucosa Rana esculenta Alkaline secretion Na+-(HCO3)n cotransport 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Chiklissa AR, Gharzouli A, Charpin G, Descroix-Vagne M, Pansu D (1992) Comparison of VIP-induced electrolyte secretion at three levels in rat small intestine. Reprod Nutr Dev 32:37–45Google Scholar
  2. 2.
    Curci S, Schettino T, Frömter E (1986) Histamine reduces Cl activity in surface epithelial cells of frog gastric mucosa. Pflügers Arch 406:204–211Google Scholar
  3. 3.
    Curci S, Debellis L, Frömter E (1987) Evidence for rheogenic sodium bicarbonate cotransport in the basolateral membrane of oxyntopeptic cells of frog gastric fundus. Pflügers Arch 408:497–504Google Scholar
  4. 4.
    Debellis L, Curci S, Frömter E (1992) Microelectrode determination of oxyntopeptic cell pH in intact frog gastric mucosa. Effect of histamine. Pflügers Arch 422:253–259Google Scholar
  5. 5.
    Debellis L, Iacovelli C, Frömter E, Curci S (1994) Model of bicarbonate secretion by resting frog stomach fundus mucosa. II. Role of the oxyntopeptic cells. Pflügers Arch 428:655–663Google Scholar
  6. 6.
    Flemström G (1977) Active alkalinization by amphibian gastric fundic mucosa in vitro. Am J Physiol 233:E1-E12Google Scholar
  7. 7.
    Flemström G (1987) Gastric and duodenal mucosal bicarbonate secretion. In: Physiology of the gastrointestinal tract. Raven Press, New York, pp 1011–1029Google Scholar
  8. 8.
    Flemström G (1980) Stimulation of HCO3 transport in isolated proximal bullfrog duodenum by prostaglandins. Am J Physiol 239:G198-G230Google Scholar
  9. 9.
    Frömter E (1983) Transport of matter through biological membranes. In: Hoppe W, Lohmann W, Markl H, Ziegler H (eds) Biophysics. Springer, Berlin Heidelberg New York, pp 465–502Google Scholar
  10. 10.
    Flemström G, Sachs G (1975) Properties of isolated antral mucosa I. General characteristics. Am J Physiol 228:1188–1198Google Scholar
  11. 11.
    Garner A, Heylings JR (1979) Stimulation of alkaline secretion in amphibian-isolated gastric mucosa by 16-16 dimethyl PGE2 and PGF2a. Gastroenterology 76:497–503Google Scholar
  12. 12.
    Holm L, Flemström G (1990) Microscopy of acid transport at the gastric surface in vivo. J Intern Med Suppl 732:91–95Google Scholar
  13. 13.
    Hubel KA (1969) Effect of luminal chloride concentration on bicarbonate secretion in rat ileum. Am J Physiol 217:40–45Google Scholar
  14. 14.
    Kunzelmann K, Gerlach L, Fröbe U, Greger R (1991) Bicarbonate permeability of epithelial chloride channels. Pflügers Arch 417:616–621Google Scholar
  15. 15.
    Maren TH (1967) Carbonic anhydrase: chemistry, physiology and inhibition. Physiol Rev 47:597–781Google Scholar
  16. 16.
    Pollard CE, Harris A, Coleman L, Argent BE (1991) Chloride channel on epithelial cells cultured from human fetal epididymis. J Membr Biol 124:275–284Google Scholar
  17. 17.
    Seki G, Frömter E (1992) Acetazolamide inhibition of basolateral Cl/HCO3 exchange in rabbit renal proximal tubule S3 segment. Pflügers Arch 422:55–59Google Scholar
  18. 18.
    Seki G, Coppola S, Frömter E (1993) Na-HCO3 cotransport functions with a coupling rate o 2 HCO3 to 1 Na+ in isolated perfused renal proximal tubule. Pflügers Arch 425:409–416Google Scholar
  19. 19.
    Sheerin HE, Field M (1975) Ileal HCO3 secretion: relationship to Na Cl transport and effect of theophylline. Am J Physiol 228:1065–1074Google Scholar
  20. 20.
    Simson JNL, Merhav A, Silen W (1981) Alkaline secretion by amphibian duodenum. II. Short-circuit current and Na+ and Cl fluxes. Am J Physiol 240:G472-G479Google Scholar
  21. 21.
    Soleimani M, Grassl SM, Aronson PS (1987) Stoichiometry of Na+-HCO3 cotransport in basolateral membrane vesicles isolated from rabbit cortex. J Clin Invest 79:1276–1280Google Scholar
  22. 22.
    Takeuchi K, Merhav A, Silen W (1982) Mechanism of luminal alkalinization by bullfrog fundic mucosa. Am J Physiol 243:G377-G388Google Scholar
  23. 23.
    Tantisira MH, Jodal M, Lundgren O (1990) Effects of heat-stable Escherichia coli enterotoxin on intestinal alkaline secretion and transepithelial potential difference in the rat intestines in vivo. Scand J Gastroenterol 25:19–28Google Scholar
  24. 24.
    Yanaka A, Carter KJ, Goddard PJ, Silen W (1991) Effect of luminal acid on intracellular pH in oxynticopeptic cells in intact frog gastric mucosa. Gastroenterology 100:606–618Google Scholar
  25. 25.
    Yoshitomi K, Burckardt B-Ch, Frömter E (1985) Rheogenic sodium-bicarbonate cotransport in the peritubular cell membrane of rat renal proximal tubule. Pflügers Arch 405:360–366Google Scholar

Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • Silvana Curci
    • 1
  • Lucantonio Debellis
    • 1
  • Rossella Caroppo
    • 1
  • Eberhard Frömter
    • 2
  1. 1.Istituto di Fisiologia GeneraleUniversità di BariBariItaly
  2. 2.Zentram der PhysiologieJ.W. Goethe UniversitätFrankfurt/MainGermany

Personalised recommendations