Intracellular microelectrode techniques and extracellular pH measurements were used to study the dependence of apical Na+/H+ exchange on mucosal and intracellular pH and on mucosal solution Na+ concentration ([Na+]o). When mucosal solution pH (pHo) was decreased in gallbladders bathed in Na(+)-containing solutions, aNai fell. The effect of pHo is consistent with titration of a single site with ...

The mechanism of luminal solution acidification was studied in Necturus gallbladder by measurement of mucosal solution and intracellular pH with glass electrodes. When the gallbladder was bathed by a Na-Ringer's solution it acidified the luminal side by a Na+-dependent, amiloride-inhibitable process. In the presence of ouabain, acidification was reduced but could be stimulated to a rate greater...

The hypothesis of Cl-/HCO s exchange across the apical membrane of the epithelial cells of Necturus gallbladder was tested by means of measurements of extracellular pH (pH.), intracellular pH (pHi), andClactivity (aCli) with ion-sensitive microelectrodes. Luminal pH changes were measured after stopping mucosal superfusion with a solution of low buffering power. Under control conditions, the lum...

The hypothesis of Cl-/HCO3- exchange across the apical membrane of the epithelial cells of Necturus gallbladder was tested by means of measurements of extracellular pH (pHo), intracellular pH (pHi), and Cl- activity (alpha Cli) with ion-sensitive microelectrodes. Luminal pH changes were measured after stopping mucosal superfusion with a solution of low buffering power. Under control conditions,...

Deviations from the physiological values of extracellular pH are monitored by multiple acid sensors. Acid-sensing ion channels are activated by moderate acidification, whereas transient receptor potential cation channels, notably TRPV1, are gated by severe acidosis. In contrast, ionotropic purinoceptor (P2X) ion channels, particularly P2X(2), and two-pore domain background K(+) channels, such a...

Gall bladder bile is more acid that hepatic bile and this has been attributed to bicarbonate absorption by the gall bladder epithelium. The aim of this study was to investigate in vitro the acid base changes that occur across the human gall bladder mucosa. Fresh gall bladder tissue was obtained at cholecystectomy and placed in an Ussing Chamber and perfused with Ringer-Krebs glucose bicarbonate...

We have hypothesized that a major role of the apical H(+)-pump in mitochondria-rich (MR) cells of amphibian skin is to energize active uptake of Cl- via an apical Cl-/HCO3(-)-exchanger. The activity of the H+ pump was studied by monitoring mucosal [H+]-profiles with a pH-sensitive microelectrode. With gluconate as mucosal anion, pH adjacent to the cornified cell layer was 0.98 +/- 0.07 (mean +/...

We examined, by using a specific PGE receptor subtype EP4 agonist and antagonist, the involvement of EP4 receptors in duodenal HCO(3)(-) secretion induced by PGE(2) and mucosal acidification in rats. Mucosal acidification was achieved by exposing a duodenal loop to 10 mM HCl for 10 min, and various EP agonists were given intravenously 10 min before the acidification. Secretion of HCO(3)(-) was ...

Intracellular microelectrode techniques were employed to study the effect of cyclic AMP on apical membrane Cl-/HCO3- exchange and electrodiffusive HCO3- transport in Necturus gallbladder epithelium. Intracellular cAMP levels were raised by addition of either the phosphodiesterase inhibitor theophylline (3 X 10(-3) M) or the adenylate cyclase activator forskolin (10(-5) M) to the serosal bathing...