Mechanism of luminal alkalinization by bullfrog fundic mucosa.
Metiamide-inhibited fundic mucosa of bullfrog secreted alkali (OH-) at 0.1-0.2 mueq.cm-2.h-1.OH- was abolished by dinitrophenol (DNP) and was decreased significantly by 4,4-didsothiocyano-2,2-disulfonate stilbene (DIDS), anoxia, or HCO3(-)-free nutrient solution. In Na+ solutions, increasing nutrient, [HCO3(-)] augmented OH- and Isc linearly while resistance (R) decreased. No such changes occurred in Na+-free nutrient solution. In all experiments, delta Isc was approximately 12 X delta OH. Replacement of Cl- in the secretory solutions or in the nutrient solutions had no significant influence on OH-. When Na+-free nutrient solutions and Cl--free secretory solutions were present, OH- decreased significantly (P less than 0.01). Increasing nutrient [Cl-] in the absence of secretory Cl- significantly (P less than 0.01) augmented OH- and Isc. In the absence of secretory Cl-, OH- and Isc were linearly related to varying nutrient [Cl-]. In tissues with nutrient solutions on the secretory side and vice versa, apparent OH- was 0.4-0.5 mueq.cm-1.h-1 and was dependent on secretory [HCO3(-)] but was not affected by DNP, DIDS, or replacement of Cl- on secretory or nutrient solutions. We conclude that 1) OH- secretion is dependent on nutrient HCO3(-) and Na+ and oxidative metabolism, 2) endogenous HCO3(-) does not contribute significantly, and 3) adequate tissue Cl- must be present for normal OH-.
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000086:Acetazolamide / Q000494:pharmacology; D000818:Animals; D001639:Bicarbonates / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D004140:Dinitrophenols / Q000494:pharmacology; D004553:Electric Conductivity; D005750:Gastric Juice / Q000187:drug effects / Q000378:metabolism*; D005753:Gastric Mucosa / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D008785:Metiamide / Q000494:pharmacology; D011892:Rana catesbeiana
D001639:Bicarbonates; D002712:Chlorides; D004140:Dinitrophenols; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D008785:Metiamide; D000086:Acetazolamide; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid