Evidence for the Presence of an Electrogenic Proton Pump on the Trout Gill Epithelium

1991 ◽  
Vol 161 (1) ◽  
pp. 119-134 ◽  
Author(s):  
HONG LIN ◽  
DAVID RANDALL
Keyword(s):  
Proton Pump ◽  
Water Proton ◽  
Gill Epithelium ◽  
Blood Ph ◽  
Water Ph ◽  
Electrogenic Proton Pump ◽  
Proton Excretion ◽  
Transport Inhibitors ◽  
Trout Gill ◽  
Transfer Mechanisms

Ion transport inhibitors, amiloride, SITS, vanadate and acetazolamide, wereadded to the water to determine the effect of ion transfer mechanisms on the acidification of water passing over the gills. In neutral water, proton excretion causes a marked reduction in gill water pH. If water pH is 2.5 units lower than blood pH, however, then this proton excretion is inhibited and all water pH changes can be accounted for by CO2 hydration and ammonia protonation. Proton excretion across the gills is insensitive to 0.1mmoll−1 amiloride and SITS but sensitive to vanadate, acetazolamide and water pH; thus, we conclude that proton excretion is mediated by an active proton pump on the apical membrane of the gill epithelium similar to that reported for the frog skin. Higher concentrations of amiloride (0.5 and 1mmoll−1) reduced both ammonia and acid excretion, presumably because of inhibition of Na+/K+-ATPase on the basolateral border ofthe gill epithelium.

Responses of trout gill ion transport systems to acute acidosis

1976 ◽  
Vol 64 (2) ◽  
pp. 511-515
Author(s):  
T. H. Kerstetter ◽  
R. Mize
Keyword(s):  
Lactic Acid ◽  
Rainbow Trout ◽  
Ion Transport ◽  
Ion Uptake ◽  
Transport Systems ◽  
Ph Changes ◽  
Blood Ph ◽  
Slow Infusion ◽  
Trout Gill

The response of rainbow trout Na+ and Cl- uptake systems to acute acidosis was tested by slow infusion of lactic acid into anaesthetized animals. Depression of blood pH by 0–4 pH unit had no effect on influx rates for either ion, and we conclude that gill ion uptake systems do not respond rapidly to blood pH changes.

Cloning and molecular characterisation of the trout (Oncorhynchus mykiss) vacuolar H(+)-ATPase B subunit

2000 ◽  
Vol 203 (3) ◽  
pp. 459-470 ◽  
Author(s):  
S.F. Perry ◽  
M.L. Beyers ◽  
D.A. Johnson
Keyword(s):  
Oncorhynchus Mykiss ◽  
Tissue Distribution ◽  
Cdna Library ◽  
Proton Pump ◽  
Northern Analysis ◽  
Mrna Levels ◽  
B Subunit ◽  
Mrna Tissue Distribution ◽  
Degenerate Oligonucleotide ◽  
Trout Gill

The current model of transepithelial ion movements in the gill of freshwater fish incorporates an apically oriented vacuolar H(+)-ATPase (H(+)V-ATPase; proton pump) that is believed to facilitate both acid excretion and Na(+) uptake. To substantiate this model, we have cloned and sequenced a cDNA encoding the B subunit of the rainbow trout (Oncorhynchus mykiss) H(+)V-ATPase. The cloning of the B subunit enabled an examination by northern analysis of its tissue distribution and expression during external hypercapnia. Degenerate oligonucleotide primers to the B subunit of the H(+)V-ATPase were designed and used in a semi-nested polymerase chain reaction (PCR) to amplify an 810 base pair (bp) product from a trout gill/kidney cDNA library. This PCR product was cloned and sequenced and then used to screen the same cDNA library. The assembled 2262 bp cDNA included an open reading frame coding for a deduced protein of 502 amino acid residues. A BLAST search of the GenBank nucleotide database revealed numerous matches to other vertebrate and invertebrate H(+)V-ATPase B subunits. Protein alignment demonstrated that the trout H(+)V-ATPase B subunit is more than 85 % identical and more than 90 % similar to those in other vertebrate species. An initial analysis of H(+)V-ATPase mRNA tissue distribution revealed significant expression in blood. Although a comparison of perfused tissues (blood removed) with non-perfused tissues demonstrated no obvious contribution of the blood to total tissue H(+)-ATPase mRNA levels, all subsequent experiments were performed using perfused tissues. Levels of H(+)V-ATPase mRNA expression were high in the gill, kidney (anterior or posterior), intestine, heart and spleen, but lower in liver and white muscle. Exposure of the fish to 12 h of external hypercapnia (water P(CO2)=7. 5 mmHg; 1 kPa) was associated with a transient increase (at 2 h) in the levels of H(+)V-ATPase B subunit mRNA in gill and kidney; liver mRNA levels were unaffected. These results are consistent with the hypothesis of an apically localised plasma membrane H(+)V-ATPase in the freshwater trout gill and that the expression of this proton pump is increased during periods of acidosis, at least in part because of an increased steady-state level of H(+)V-ATPase mRNA.

scholarly journals Tricellular tight junction-associated angulins in the gill epithelium of rainbow trout

2018 ◽  
Vol 315 (2) ◽  
pp. R312-R322 ◽  
Author(s):  
Dennis Kolosov ◽  
Scott P. Kelly
Keyword(s):  
Tight Junction ◽  
Transcript Abundance ◽  
Barrier Properties ◽  
Mrna Abundance ◽  
Gill Epithelium ◽  
Molecular Physiology ◽  
Permeability Characteristics ◽  
Gill Cells ◽  
Associated Proteins ◽  
Trout Gill

Molecular physiology of the tricellular tight junction (tTJ)-associated proteins lipolysis-stimulated lipoprotein receptor ( lsr, = angulin-1) and an immunoglobulin-like domain-containing receptor ( ildr2, ≈angulin-3) was examined in model trout gill epithelia. Transcripts encoding lsr and ildr2 are broadly expressed in trout organs. A reduction in lsr and ildr2 mRNA abundance was observed during and after confluence in flask-cultured gill cells. In contrast, as high-resistance and low-permeability characteristics developed in a model gill epithelium cultured on permeable polyethylene terephthalate membrane inserts, lsr and ildr2 transcript abundance increased. However, as epithelia entered the developmental plateau phase, lsr abundance returned to initial values, while ildr2 transcript abundance remained elevated. When mitochondrion-rich cells were introduced to model preparations, lsr mRNA abundance was unaltered and ildr2 mRNA abundance significantly increased. Transcript abundance of ildr2 was not altered in association with corticosteroid-induced tightening of the gill epithelium, while lsr mRNA abundance decreased. Transcriptional knockdown of the tTJ protein tricelluin (Tric) reduced Tric abundance, increased gill epithelium permeability, and increased lsr without significantly altering ildr2 transcript abundance. Data suggest that angulins contribute to fish gill epithelium barrier properties but that Lsr and Ildr2 seem likely to play different roles. This is because ildr2 typically exhibited increased abundance in association with decreased model permeability, while lsr abundance changed in a manner that suggested a role in Tric recruitment to the tTJ.

scholarly journals Golgi membranes contain an electrogenic H+ pump in parallel to a chloride conductance.

1983 ◽  
Vol 97 (4) ◽  
pp. 1303-1308 ◽  
Author(s):  
J Glickman ◽  
K Croen ◽  
S Kelly ◽  
Q Al-Awqati
Keyword(s):  
Membrane Potential ◽  
Proton Pump ◽  
Gradient Centrifugation ◽  
Chloride Conductance ◽  
F1 Atpase ◽  
Chloride Uptake ◽  
Golgi Vesicles ◽  
Galactosyl Transferase ◽  
Golgi Membranes ◽  
Electrogenic Proton Pump

Rat liver Golgi vesicles were isolated by differential and density gradient centrifugation. A fraction enriched in galactosyl transferase and depleted in plasma membrane, mitochondrial, endoplasmic reticulum, and lysosomal markers was found to contain an ATP-dependent H+ pump. This proton pump was not inhibited by oligomycin but was sensitive to N-ethyl maleimide, which distinguishes it from the F0-F1 ATPase of mitochondria. GTP did not induce transport, unlike the lysosomal H+ pump. The pump was not dependent on the presence of potassium nor was it inhibited by vanadate, two of the characteristics of the gastric H+ ATPase. Addition of ATP generated a membrane potential that drove chloride uptake into the vesicles, suggesting that Golgi membranes contain a chloride conductance in parallel to an electrogenic proton pump. These results demonstrate that Golgi vesicles can form a pH difference and a membrane potential through the action of an electrogenic proton translocating ATPase.

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