title: Identification of the bicarbonate secretory cell of the turtle bladder.
abstract: The turtle bladder consists primarily of two mucosal cell types, mitochondrial rich (MR) and granular (G) cells. The MR cells secrete H+. In addition, the bladder secretes HCO3-, an energy-requiring Cl(-)-dependent transport system. These studies were designed to identify the cell type responsible for HCO3- secretion. Specific HCO3- and H+ secretory inhibitors were added to alter O2 consumption of MR and G cells. Cells were separated by Ficoll density centrifugation. Ouabain (10(-4) M) was used in all studies to eliminate O2 consumption associated with Na+ transport. O2 consumption of cells treated with 10(-4) M 4-acetamido-4'-isothiocyanostilbene-2,2'-sulfonic acid (SITS), which indirectly inhibits H+ secretion, was compared with cells additionally treated with 5 X 10(-4) M acetazolamide, an inhibitor of both H+ and HCO3- secretion. O2 consumption of MR cells treated with SITS alone was significantly greater than that of MR cells additionally treated with acetazolamide (delta = 0.56 +/- 0.10 microliter O2 X h-1 X mg protein-1, n = 6, P less than 0.003). There was no significant difference in G cells similarly treated. Another means of selectively altering H+ and HCO3- transports and their associated metabolic rates is to manipulate the Cl- concentration of the incubation medium. In a Cl(-)-rich medium, HCO3- and H+ transports are maximized. In low Cl(-)-SO2-4 medium, HCO3- secretion is selectively reduced.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D000086:Acetazolamide / Q000494:pharmacology; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology; D010101:Oxygen Consumption / Q000187:drug effects; D014426:Turtles / Q000033:anatomy & histology*; D001743:Urinary Bladder / Q000166:cytology*
chemical_list: D001639:Bicarbonates; D002712:Chlorides; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D010042:Ouabain; D006859:Hydrogen; D000086:Acetazolamide