Related Experiment Video
Updated: May 13, 2026

Whole-cell Patch-clamp Recordings of Isolated Primary Epithelial Cells from the Epididymis
Published on: August 3, 2017
Effect of secretion on intracellular pH regulation in isolated rat bile duct epithelial cells
1Department of Internal Medicine, Yale University, School of Medicine, New Haven, Connecticut 06510.
Abstract:
The effects of secretin on ion transport mechanisms involved in regulation of intracellular pH (pHi) and HCO3- excretion were characterized in bile duct epithelial (BDE) cells isolated from normal rat liver. pHi was measured with 2,7-bis(carboxy-ethyl)-5(6)-carboxy-fluorescein-acetomethylester (BCECF-AM) using a microfluorimetric method. Basal pHi of BDE was 7.04 +/- 0.06 in Hepes and 7.16 +/- 0.10 in KRB and was unaffected by secretin (50-200 nM). Recovery rates from an acid load in Hepes or in KRB media (with and without amiloride) were also not altered by secretin, indicating that Na+/H+ exchange and Na+/HCO3- cotransport were not affected by this hormone. After acute Cl- removal, pHi rose 0.24 +/- 0.08 pHU at a maximal rate of 0.125 +/- 0.06 pHU/min (H+ flux rates = 6.02 +/- 3.27 mM/min) and recovered after Cl- readmission (0.188 +/- 0.08 pHU/min; H+ flux rates = 11.82 +/- 5.34 mM/min). Pretreatment with 1 mM DIDS inhibited the effects of Cl- removal, while valinomycin, which induces cell depolarization, enhanced these effects, probably by stimulating electrogenic HCO3- influx. Secretin significantly increased both the maximal rate of alkalinization after Cl- removal (P < 0.012) and of pHi recovery after Cl- readmission (P < 0.025), indicating stimulation of Cl-/HCO3- exchange activity. These findings were reproduced with N6,2'-O-Dibutyryladenosine-3',5'-cyclic monophosphate (DBcAMP). The Cl- channel blocker 5-nitro-2'-(3-phenylpropylamino)-benzoate (NPPB, 10 microM) significantly decreased the effects of secretin and DBcAMP on the pHi changes promoted by acute Cl- removal/readmission. These findings establish that secretin stimulates the activity of the Cl-/HCO3- exchanger in BDE cells, probably by activating Cl- channels via the intracellular messenger cAMP. This in turn depolarizes the cell, stimulating electrogenic Na+/HCO3- symport. The cell depolarization induced by Cl- channel activation should enhance HCO3- entrance through electrogenic Na+/HCO3- symport, which in turn stimulates the Cl-/HCO3- exchange. These mechanisms could account for secretin stimulated bicarbonate secretion in bile.
More Related Videos
07:00Mechanisms Underlying Gut Hormone Secretion Using the Isolated Perfused Rat Small Intestine
Published on: February 26, 2019
10:12Isolation and 3D Collagen Sandwich Culture of Primary Mouse Hepatocytes to Study the Role of Cytoskeleton in Bile Canalicular Formation In Vitro
Published on: December 20, 2019
Related Concept Videos
Stomach pH Regulation
The acid-secreting gastric mucosal epithelial cells (parietal cells) lining the stomach lumen maintain the low pH in the lumen. Numerous ion transporters and channels on these parietal...
pH Regulation in Cells
Cytosolic pH
Under physiological conditions, the cytosolic pH is slightly more acidic than the extracellular pH. However, cells must prevent further acidification of their cytosol to...
Bile
Bile is released when dietary fats enter...
Reabsorption and Secretion in the DCT and Collecting Duct
The distal part of the DCT, along with the...
Renal Regulation of Acid-Base Balance
In the kidneys, cells within the proximal convoluted tubules (PCT) and the collecting ducts secrete hydrogen ions (H+) into the tubular fluid. Specifically, in the PCT, Na+/H+ antiporters secrete H+ while reabsorbing Na+.
However, the intercalated cells in...
Hepatic Drug Excretion: Influencing Factors