Regulation of ion transport by pH and [HCO3−] in isolated gills of the crab Neohelice (Chasmagnathus) granulata

2008 ◽  
Vol 294 (3) ◽  
pp. R1033-R1043 ◽  
Author(s):  
Martin Tresguerres ◽  
Scott K. Parks ◽  
Sebastian E. Sabatini ◽  
Greg G. Goss ◽  
Carlos M. Luquet
Keyword(s):  
Carbonic Anhydrase ◽  
Ion Transport ◽  
Acid Secretion ◽  
Cellular Response ◽  
Low Ph ◽  
Potential Difference ◽  
Anion Exchangers ◽  
Transepithelial Potential Difference ◽  
Chasmagnathus Granulata ◽  
First Time

Posterior isolated gills of Neohelice ( Chasmagnathus) granulatus were symmetrically perfused with hemolymph-like saline of varying [HCO3−] and pH. Elevating [HCO3−] in the saline from 2.5 to 12.5 mmol/l (pH 7.75 in both cases) induced a significant increase in the transepithelial potential difference ( Vte), a measure of ion transport. The elevation in [HCO3−] also induced a switch from acid secretion (−43.7 ± 22.5 μequiv·kg−1·h−1) in controls to base secretion (84.7 ± 14.4 μequiv·kg−1·h−1). The HCO3−-induced Vte increase was inhibited by basolateral acetazolamide (200 μmol/l), amiloride (1 mmol/l), and ouabain (5 mmol/l) but not by bafilomycin (100 nmol/l). The Vte response to HCO3− did not take place in Cl−-free conditions; however, it was unaffected by apical SITS (2 mmol/l) or DIDS (1 mmol/l). A decrease in pH from 7.75 to 7.45 pH units in the perfusate also induced a significant increase in Vte, which was matched by a net increase in acid secretion of 67.8 ± 18.4 μequiv kg−1 h−1. This stimulation was sensitive to basolateral acetazolamide, bafilomycin, DIDS, and Na+-free conditions, but it still took place in Cl−-free saline. Therefore, the cellular response to low pH is different from the HCO3−-stimulated response. We also report V-H+-ATPase- and Na+-K+-ATPase-like immunoreactivity in gill sections for the first time in this crab. Our results suggest that carbonic anhydrase (CA), basolateral Na+/H+ exchangers and Na+-K+-ATPase and apical anion exchangers participate in the HCO3−-stimulated response, while CA, apical V-H+-ATPase and basolateral HCO3−-dependent cotransporters mediate the response to low pH.

scholarly journals Fluid reabsorption and ion transport by the lower Malpighian tubules of adult female Drosophila.

1995 ◽  
Vol 198 (8) ◽  
pp. 1647-1653 ◽  
Author(s):  
M J O'Donnell ◽  
S H Maddrell
Keyword(s):  
Drosophila Melanogaster ◽  
Ion Transport ◽  
Adult Female ◽  
Malpighian Tubules ◽  
Potential Difference ◽  
High Rate ◽  
Fluid Reabsorption ◽  
Transepithelial Potential Difference ◽  
The Common

The properties of the Malpighian tubules of Drosophila melanogaster change along their length. The upstream main segments secrete K(+)-rich fluid at a high rate. From this, the lower tubules reabsorb significant amounts of water and K+. Under stimulation, K+ reabsorption is accelerated. In addition, the lower tubules acidify the fluid passed to them by the main segments and secrete Ca2+ into it, adding to that transported there by the upstream epithelium. In contrast to the lumen-positive transepithelial potential difference (TEP) of the main segments, the TEP in the lower tubules is much lower and becomes lumen-negative close to their downstream junction with the common ureter. We suggest that the role of the lower tubule is to reduce the flow of K(+)-rich fluid that passes to the hindgut; this allows the hindgut to process the flow of excretory fluid more thoroughly.

An hypothesis for discovery of inhibitors of gastric acid secretion

1964 ◽  
Vol 207 (3) ◽  
pp. 613-618 ◽  
Author(s):  
Marian E. LeFevre ◽  
Edmund J. Gohmann ◽  
Warren S. Rehm
Keyword(s):  
Carbonic Anhydrase ◽  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Electrical Resistance ◽  
Inhibitory Action ◽  
Potential Difference ◽  
Ammonium Ions ◽  
Working Hypothesis

Davenport discovered that thiocyanate inhibits gastric acid secretion. The original working hypothesis, that this action of thiocyanate is due to inhibition of carbonic anhydrase, was successful in stimulating further work but is now no longer tenable. We propose a new working hypothesis according to which the inhibitory action is dependent on the presence of a nitrogen with a pair of unshared electrons. This hypothesis was tested by studying the effects of nitrite, cyanate, and ammonium ions on the in vitro frog's stomach. It was found that the addition of these compounds to the nutrient side reversibly inhibits H+ secretion in the same concentration range as that found for thiocyanate, i.e., 0.5–10 mm. Reduction of the H+ rate to approximately zero was associated with an increase in the transmucosal potential difference and electrical resistance to levels characteristic of the resting stomach. Acetate and nitrate in the same and higher concentrations did not inhibit the H+ rate. The hypothesis has been fruitful in that three new gastric inhibitors have been discovered, and it is hoped that it will be successful in stimulating much further work before it too becomes untenable.

Regional bioelectric properties of porcine airway epithelium

1992 ◽  
Vol 73 (5) ◽  
pp. 2021-2027 ◽  
Author(s):  
S. T. Ballard ◽  
S. M. Schepens ◽  
J. C. Falcone ◽  
G. A. Meininger ◽  
A. E. Taylor
Keyword(s):  
Ion Transport ◽  
Transport Properties ◽  
Airway Epithelium ◽  
Small Airway ◽  
Potential Difference ◽  
Lumen Diameter ◽  
Free Solution ◽  
Airway Epithelia ◽  
Transepithelial Potential Difference ◽  
Fractional Inhibition

Ion transport properties of pulmonary small airway epithelia are poorly understood. To characterize these properties, airways were excised from anesthetized pigs. Transepithelial potential difference (PD) and conductance were measured in five airway regions: trachea (T, 7.9 +/- 0.2 mm diam), mainstem bronchi (MB, 5.5 +/- 0.2 mm diam), large bronchi (LB, 1.69 +/- 0.12 mm diam), small bronchi (SB, 0.70 +/- 0.06 mm diam), and bronchioles (BR, 0.25 +/- 0.05 mm diam). T and MB were mounted in Ussing-type chambers, and LB, SB, and BR were cannulated with pipettes and perfused. PDs of control tissues were -9.7 +/- 0.8 mV (T), -4.0 +/- 0.5 mV (MB), -4.3 +/- 1.0 mV (LB), -4.5 +/- 0.4 mV (SB), and -1.5 +/- 0.4 mV (BR), lumen negative. Amiloride significantly (P < 0.05) inhibited PDs by 25-70% in all airway regions and decreased conductance 17–33% in all regions except LB where a 10% increase was observed. Bumetanide significantly reduced the amiloride-insensitive PD 54–62% in all regions except BR. Bumetanide had little effect on conductance in T, SB, and BR, but conductance was increased in MB and LB. All airways except the smallest BR significantly hyperpolarized when the solution that bathed the lumen was replaced with Cl(-)-free solution. In bronchioles, hyperpolarization by luminal Cl(-)-free solution was inversely related to fractional inhibition of PD with amiloride but directly related to lumen diameter. These results suggest that 1) porcine tracheas, bronchi, and bronchioles actively absorb Na+, and 2) secretion of Cl- may occur in all airway regions except small bronchioles.

scholarly journals Measurement of Multi Ion Transport through Human Bronchial Epithelial Cell Line Provides an Insight into the Mechanism of Defective Water Transport in Cystic Fibrosis

Membranes ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 43 ◽  
Author(s):  
Miroslaw Zajac ◽  
Andrzej Lewenstam ◽  
Piotr Bednarczyk ◽  
Krzysztof Dolowy
Keyword(s):  
Cystic Fibrosis ◽  
Ion Transport ◽  
Water Absorption ◽  
Cell Line ◽  
Water Transport ◽  
Chloride Ions ◽  
Potential Difference ◽  
Bronchial Epithelial ◽  
Transepithelial Potential ◽  
Transepithelial Potential Difference

We measured concentration changes of sodium, potassium, chloride ions, pH and the transepithelial potential difference by means of ion-selective electrodes, which were placed on both sides of a human bronchial epithelial 16HBE14σ cell line grown on a porous support in the presence of ion channel blockers. We found that, in the isosmotic transepithelial concentration gradient of either sodium or chloride ions, there is an electroneutral transport of the isosmotic solution of sodium chloride in both directions across the cell monolayer. The transepithelial potential difference is below 3 mV. Potassium and pH change plays a minor role in ion transport. Based on our measurements, we hypothesize that in a healthy bronchial epithelium, there is a dynamic balance between water absorption and secretion. Water absorption is caused by the action of two exchangers, Na/H and Cl/HCO3, secreting weakly dissociated carbonic acid in exchange for well dissociated NaCl and water. The water secretion phase is triggered by an apical low volume-dependent factor opening the Cystic Fibrosis Transmembrane Regulator CFTR channel and secreting anions that are accompanied by paracellular sodium and water transport.

Expression patterns of two carbonic anhydrase genes, Na+/K+-ATPase and V-type H+-ATPase, in the freshwater crayfish, Cherax quadricarinatus, exposed to low pH and high pH

2017 ◽  
Vol 65 (1) ◽  
pp. 50 ◽  
Author(s):  
Muhammad Yousuf Ali ◽  
Ana Pavasovic ◽  
Peter B. Mather ◽  
Peter J. Prentis
Keyword(s):  
Carbonic Anhydrase ◽  
Expression Patterns ◽  
Maximum Level ◽  
Low Ph ◽  
Freshwater Crayfish ◽  
Α Subunit ◽  
Cherax Quadricarinatus ◽  
High Ph ◽  
Internal Ph ◽  
Ph Conditions

Carbonic anhydrase (CA), Na+/K+-ATPase (NKA) and Vacuolar-type H+-ATPase (HAT) play vital roles in osmoregulation and pH balance in decapod crustaceans. As variable pH levels have a significant impact on the physiology of crustaceans, it is crucial to understand the mechanisms by which an animal maintains its internal pH. We examined expression patterns of cytoplasmic (CAc) and membrane-associated form (CAg) of CA, NKA α subunit and HAT subunit a in gills of freshwater crayfish, Cherax quadricarinatus, at three pH levels – 6.2, 7.2 (control) and 8.2 – over 24 h. Expression levels of CAc were significantly increased at low pH and decreased at high pH conditions 24 h after transfer. Expression increased at low pH after 12 h, and reached its maximum level by 24 h. CAg showed a significant increase in expression at 6 h after transfer at low pH. Expression of NKA significantly increased at 6 h after transfer to pH 6.2 and remained elevated for up to 24 h. Expression for HAT and NKA showed similar patterns, where expression significantly increased 6 h after transfer to low pH and remained significantly elevated throughout the experiment. Overall, CAc, CAg, NKA and HAT gene expression is induced at low pH conditions in freshwater crayfish.

scholarly journals Immunocytochemical localization of mitochondrial carbonic anhydrase in rat tissues.

1991 ◽  
Vol 39 (4) ◽  
pp. 451-459 ◽  
Author(s):  
H K Väänänen ◽  
N D Carter ◽  
S J Dodgson
Keyword(s):  
Skeletal Muscle ◽  
Carbonic Anhydrase ◽  
Cardiac Tissue ◽  
Polyclonal Antiserum ◽  
Heterogeneous Population ◽  
Rat Tissues ◽  
Staining Reaction ◽  
Gastric Parietal Cells ◽  
First Time ◽  
Carbonic Anhydrase Gene

We used a monospecific polyclonal antiserum against mitochondrial carbonic anhydrase (CA V) from rat liver to study tissue localization of this new member of the carbonic anhydrase gene family. Strong granular immunostaining reaction of CA V was observed in hepatocytes, myocardium, and in certain populations of skeletal muscle fibers. This is the first time that mitochondrial carbonic anhydrase is described in cardiac tissue of rat or any other species. Different epithelial cells revealed very heterogeneous staining reaction, suggesting that mitochondria are a heterogeneous population with respect to their CA V content. Many cells in different glandular epithelia did not show any CA V, whereas some cells, such as gastric parietal cells, were intensely stained with CA V antibodies. No systematic co-expression of CA V with CA I, CA II, or CA III was observed, although the distribution of CA V in skeletal muscle was somewhat similar to that of CA III. Connective tissue cells such as fibroblasts, chondroblasts, and osteoblasts were negative.

Nitric oxide-mediated regulation of transepithelial sodium and chloride transport in murine nasal epithelium

1999 ◽  
Vol 276 (3) ◽  
pp. L466-L473 ◽  
Author(s):  
Heather L. Elmer ◽  
Kristine G. Brady ◽  
Mitchell L. Drumm ◽  
Thomas J. Kelley
Keyword(s):  
Nitric Oxide ◽  
Chloride Transport ◽  
Chloride Secretion ◽  
Inos Expression ◽  
Potential Difference ◽  
Nasal Epithelium ◽  
Sodium Absorption ◽  
No Production ◽  
Transepithelial Potential ◽  
Transepithelial Potential Difference

Transepithelial ion transport is regulated by a variety of cellular factors. In light of recent evidence that nitric oxide (NO) production is decreased in cystic fibrosis airways, we examined the role of NO in regulating sodium and chloride transport in murine nasal epithelium. Acute intervention with the inducible NO synthase (iNOS)-selective inhibitor S-methylisothiourea resulted in an increase of amiloride-sensitive sodium absorption observed as a hyperpolarization of nasal transepithelial potential difference. Inhibition of iNOS expression with dexamethasone also hyperpolarized transepithelial potential difference, but only a portion of this increase proved to be amiloride sensitive. Chloride secretion was significantly inhibited in C57BL/6J mice by the addition of both S-methylisothiourea and dexamethasone. Mice lacking iNOS expression [NOS2(−/−)] also had a decreased chloride-secretory response compared with control mice. These data suggest that constitutive NO production likely plays some role in the downregulation of sodium absorption and leads to an increase in transepithelial chloride secretion.

Calcium secretion in canine tracheal mucosa

1985 ◽  
Vol 59 (4) ◽  
pp. 1191-1195 ◽  
Author(s):  
F. J. Al-Bazzaz ◽  
T. Jayaram
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Potential Difference ◽  
Secretory Process ◽  
Metabolic Inhibitor ◽  
Tracheal Mucosa ◽  
Transepithelial Potential ◽  
Transepithelial Potential Difference

Calcium (Ca) affects many cellular functions of the respiratory tract mucosa and might alter the viscoelastic properties of mucus. To evaluate Ca homeostasis in a respiratory epithelium we investigated transport of Ca by the canine tracheal mucosa. Mucosal tissues were mounted in Ussing-type chambers and bathed with Krebs-Henseleit solution at 37 degrees C. Unidirectional fluxes of 45Ca were determined in tissues that were matched by conductance and short-circuit current (SCC). Under short-circuit conditions there was a significant net Ca secretion of 1.82 +/- 0.36 neq . cm-2 . h-1 (mean +/- SE). Under open-circuit conditions, where the spontaneous transepithelial potential difference could attract Ca toward the lumen, net Ca secretion increased significantly to 4.40 +/- 1.14 compared with 1.54 +/- 1.17 neq . cm-2 . h-1 when the preparation was short-circuited. Addition of a metabolic inhibitor, 2,4-dinitrophenol (2 mM in the mucosal bath), decreased tissue conductance and SCC and slightly decreased the unidirectional movement of Ca from submucosa to lumen. Submucosal epinephrine (10 microM) significantly enhanced Ca secretion by 2.0 +/- 0.63 neq . cm-2 . h-1. Submucosal ouabain (0.1 mM) failed to inhibit Ca secretion. The data suggest that canine tracheal mucosa secretes Ca; this secretory process is augmented by epinephrine or by the presence of a transepithelial potential difference as found under in vivo conditions.

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