Histochemical localization of Na+–K+ ATPase and carbonic anhydrase activity in gills of 17 fish species

1988 ◽  
Vol 66 (11) ◽  
pp. 2398-2405 ◽  
Author(s):  
David M. Conley ◽  
Jon Mallatt
Keyword(s):  
Carbonic Anhydrase ◽  
Atpase Activity ◽  
Carbonic Anhydrase Activity ◽  
Chloride Cells ◽  
Shark Species ◽  
Acid Base ◽  
Pavement Cells ◽  
Leopard Shark ◽  
Biochemical Assays ◽  
Definite Correlation

Activities of two enzymes considered to be involved in NaCl regulation, Na+–K+ ATPase and carbonic anhydrase, were localized in gill epithelia of 14 teleost, 2 agnathan, and 1 shark species through light microscopic histochemistry. Findings were confirmed by use of appropriate inhibitors (ouabain, acetazolamide). Na+–K+ ATPase activity was detected in chloride cells of most marine teleost species (six of eight) and of marine leopard shark and hagfish, but never in freshwater fish gills. In general, this finding agrees with past biochemical assays showing gill Na+–K+ ATPase activity to be highest in marine teleosts. Staining for carbonic anhydrase took one of three patterns among species: gill pavement cells or chloride cells, or both, were stained. Interspecific distribution of these patterns bore little relation to taxonomy or to habitat salinity, although chloride cells of euryhaline teleosts seemed more likely to stain than chloride cells of stenohaline teleosts, freshwater or marine. Given the lack of a definite correlation with salinity, it is concluded that fish gill carbonic anhydrase may not function in NaCl regulation as much as in acid–base regulation; the enzyme's role in preventing systemic pH imbalance is discussed.

Effect of acetazolamide on gas exchange and acid-base control after maximal exercise

1992 ◽  
Vol 72 (1) ◽  
pp. 278-287 ◽  
Author(s):  
J. M. Kowalchuk ◽  
G. J. Heigenhauser ◽  
J. R. Sutton ◽  
N. L. Jones
Keyword(s):  
Carbonic Anhydrase ◽  
Muscle Power ◽  
Inorganic Ions ◽  
Carbonic Anhydrase Activity ◽  
Co2 Production ◽  
Acid Base ◽  
Carbonic Anhydrase Inhibition ◽  
Severe Exercise ◽  
Arterial Plasma ◽  
End Tidal

To investigate the interactions between the systems that contribute to acid-base homeostasis after severe exercise, we studied the effects of carbonic anhydrase inhibition on exchange of strong ions and CO2 in six subjects after 30 s of maximal isokinetic cycling exercise. Each subject exercised on two randomly assigned occasions, a control (CON) condition and 30 min after intravenous injection of 1,000 mg acetazolamide (ACZ) to inhibit blood carbonic anhydrase activity. Leg muscle power output was similar in the two conditions; peak O2 uptake (VO2) after exercise was lower in ACZ (2,119 +/- 274 ml/min) than in CON (2,687 +/- 113, P less than 0.05); peak CO2 production (VCO2) was also lower (2,197 +/- 241 in ACZ vs. 3,237 +/- 87 in CON, P less than 0.05) and was accompanied by an increase in the recovery half-time from 1.7 min in CON to 2.3 min in ACZ. Whereas end-tidal PCO2 was lower in ACZ than in CON, arterial PCO2 (PaCO2) was higher, and a large negative end-tidal-to-arterial difference (less than or equal to 20 Torr) was present in ACZ on recovery. In ACZ, postexercise increases in arterial plasma [Na+] and [K+] were greater but [La-] was lower. Arteriovenous differences across the forearm showed a greater uptake of La- and Cl- in CON than in ACZ. Carbonic anhydrase inhibition with ACZ, in addition to impairing equilibration of the CO2 system to the acid-base challenge of exercise, was accompanied by changes in equilibration of strong inorganic ions. A lowered plasma [La-] was not accompanied by greater uptake of La- by inactive muscle.

Why do hagfish have gill "chloride cells" when they need not regulate plasma NaCl concentration?

1987 ◽  
Vol 65 (8) ◽  
pp. 1956-1965 ◽  
Author(s):  
Jon Mallatt ◽  
David M. Conley ◽  
Richard L. Ridgway
Keyword(s):  
Carbonic Anhydrase ◽  
Ion Transport ◽  
Specific Activity ◽  
Carbonic Anhydrase Activity ◽  
Chloride Cells ◽  
Gillichthys Mirabilis ◽  
The Pacific ◽  
Nacl Concentration ◽  
Tubular System ◽  
Freshwater Teleosts

Two enzymes implicated in branchial ion transport, Na+-K+-ATPase and carbonic anhydrase, were localized in gill ionocytes ("chloride cells") of the Pacific hagfish, Eptatretus stouti, by light microscopic histochemical techniques. In hagfish, ouabain-sensitive Na+-K+-ATPase activity was confined to apical halves of ionocytes, where most of the cytoplasmic tubular system is located. In marine teleosts, Na+-K+-ATPase was noted in chloride cells and erythrocytes. Acetazolamide and potassium cyanate sensitive carbonic anhydrase activity occurred throughout the cytoplasm and nucleus of hagfish ionocytes. Biochemical assay of hagfish gill homogenates for Na+-K+-ATPase yielded a specific activity of 3.1 μmol Pi∙mg protein−1∙h−1 at 37 °C. This resembles values we obtained for freshwater fish (Carassius auratus: 3.3 μmol Pi∙mg protein−1∙h−1; Tilapia shirana: 3.7 μmol Pi∙mg protein−1∙h−1), and is less than values we obtained for marine teleosts (Pomacentrus spp.: 13 μmol Pi∙mg protein−1∙h−1; Gillichthys mirabilis: 6.7 μmol Pi∙mg protein−1∙h−1). Hagfish resemble freshwater teleosts in many other gill features related to ion transport. The presence of carbonic anhydrase in gill ionocytes of hagfish supports the proposal that these cells function in acid–base regulation, i.e., that they exchange H+ for Na+ and [Formula: see text] for Cl−.

Effects of Acid Water and Aluminum on Parr–Smolt Transformation and Seawater Tolerance in Atlantic Salmon, Salmo salar

1993 ◽  
Vol 50 (9) ◽  
pp. 1816-1827 ◽  
Author(s):  
Magne Staurnes ◽  
Per Blix ◽  
Ola B. Reite
Keyword(s):  
Carbonic Anhydrase ◽  
Atlantic Salmon ◽  
Atpase Activity ◽  
Salmo Salar ◽  
Carbonic Anhydrase Activity ◽  
Low Ph ◽  
Soft Water ◽  
Control Fish ◽  
Exposed Fish ◽  
Seawater Tolerance

Smolting Atlantic salmon, Salmo salar, were kept from 11 April to 24 May in soft water of pH 5 or in soft water of pH 5 and 50 μg aluminum (Al)∙L−1. Control fish were kept in soft water of pH 6.3–6.5. Water temperature was 8–14 °C. In mid-May, some of the control smolts were transferred to the test conditions for 8 d. Exposure to acid water resulted in osmoregulatory failure and high mortality rate. Al strongly enhanced toxicity. Sensitivity to low pH or low pH/Al exposure greatly increased when fish had developed to seawater tolerant smolts. In control and acid-exposed fish, gill carbonic anhydrase activity remained unchanged throughout the experiment whereas in Al-exposed fish, carbonic anhydrase activity decreased. Gill Na+K+-ATPase activity in control fish peaked in mid-May simulanteously with development of seawater tolerance. Fish from both acid-exposed groups had low seawater tolerance. Na+,K+-ATPase activity declined to 60% of start value in acid-exposed fish and to parr level in Al-exposed fish. Hypoosmoregulatory ability was linearly correlated with gill Na+K+-ATPase activity. Reduction in plasma Na+ concentration in acid-exposed fish was linearly correlated with the reduction in gill Na+,K+-ATPase activity.

scholarly journals Tissue accumulation and the effects of long-term dietary copper contamination on osmoregulation in the mudflat fiddler crab Minuca rapax (Crustacea, Ocypodidae)

2020 ◽  
Author(s):  
MV Capparelli ◽  
JC McNamara ◽  
MG Grosell
Keyword(s):  
Carbonic Anhydrase ◽  
Atpase Activity ◽  
Fiddler Crab ◽  
Carbonic Anhydrase Activity ◽  
Copper Accumulation ◽  
Acid Base Balance ◽  
Dietary Copper ◽  
Base Balance ◽  
Copper Delivery

AbstractWe examined copper accumulation in the hemolymph, gills and hepatopancreas, and hemolymph osmolality, Na+ and Cl- concentrations, together with gill Na+/K+-ATPase and carbonic anhydrase activities, after dietary copper delivery (0, 100 or 500 µg Cu/g) for 12 days in a fiddler crab, Minuca rapax. In contaminated crabs, copper concentration decreased in the hemolymph and hepatopancreas, but increased in the gills. Hemolymph osmolality and gill Na+/K+-ATPase activity increased while hemolymph [Na+] and [Cl-] and gill carbonic anhydrase activity decreased. Excretion likely accounts for the decreased hemolymph and hepatopancreas copper titers. Dietary copper clearly affects osmoregulatory ability and hemolymph Na+ and Cl- regulation in M. rapax. Gill copper accumulation decreased carbonic anhydrase activity, suggesting that dietary copper affects acid-base balance. Elevated gill Na+/K+-ATPase activity appears to compensate for the ion-regulatory disturbance. These effects of dietary copper illustrate likely impacts on semi-terrestrial species that feed on metal contaminated sediments.

Activities and subcellular localizations of enzymes implicated in gastroduodenal bicarbonate secretion

1984 ◽  
Vol 247 (2) ◽  
pp. G133-G139 ◽  
Author(s):  
D. Stiel ◽  
D. J. Murray ◽  
T. J. Peters
Keyword(s):  
Plasma Membrane ◽  
Carbonic Anhydrase ◽  
Atpase Activity ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Basolateral Membrane ◽  
Duodenal Mucosa ◽  
Carbonic Anhydrase Activity ◽  
Marker Enzymes ◽  
Alpha Glucosidase

Analytical subcellular fractionation of tissue whole homogenates and microanalysis of organelle marker enzymes were used to study the activity and subcellular localization of enzymes implicated in HCO3 secretion in rat duodenal and gastric antral mucosae. The following organelles, characterized by their marker enzymes, were located in the density gradients: cytosol (lactate dehydrogenase), plasma membrane (5'-nucleotidase), peroxisomes (catalase), mitochondria (succinate dehydrogenase), endoplasmic reticulum (Tris-resistant alpha-glucosidase), lysosomes (N-beta-acetylglucosaminidase), and brush-border membrane (Zn2+-resistant alpha-glucosidase and alkaline phosphatase). Compared with gastric antrum, rat duodenal mucosa contained over twice the activity of HCO3-ATPase and of Na+-K+-ATPase but less than one-tenth the activity of carbonic anhydrase. Duodenal HCO3-ATPase activity was observed in both mitochondrial and brush-border membrane fractions, whereas antral HCO3-ATPase activity was confined to mitochondria. Na+-K+-ATPase activity was found largely in the basolateral membrane (duodenum) and plasma membrane (antrum). In both tissues carbonic anhydrase activity was localized to the cytosolic fraction. These observations offer further evidence that differing biochemical mechanisms underlie HCO3 secretion by gastric and duodenal epithelia.

Does gill boundary layer carbonic anhydrase contribute to carbon dioxide excretion: a comparison between dogfish (Squalus acanthias) and rainbow trout (Oncorhynchus mykiss)

1999 ◽  
Vol 202 (6) ◽  
pp. 749-756 ◽  
Author(s):  
S.F. Perry ◽  
K.M. Gilmour ◽  
N.J. Bernier ◽  
C.M. Wood
Keyword(s):  
Carbon Dioxide ◽  
Boundary Layer ◽  
Rainbow Trout ◽  
Carbonic Anhydrase ◽  
Carbonic Anhydrase Activity ◽  
Squalus Acanthias ◽  
Stopped Flow ◽  
Acid Base ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Co2 Excretion

In vivo experiments were conducted on spiny dogfish (Squalus acanthias) and rainbow trout (Oncorhynchus mykiss) in sea water to determine the potential role of externally oriented or gill boundary layer carbonic anhydrase in carbon dioxide excretion. This was accomplished by assessing pH changes in expired water using a stopped-flow apparatus. In dogfish, expired water was in acid-base disequilibrium as indicated by a pronounced acidification (delta pH=−0.11+/−0.01; N=22; mean +/− s.e.m.) during the period of stopped flow; inspired water, however, was in acid-base equilibrium (delta pH=−0.002+/−0.01; N=22). The acid-base disequilibrium in expired water was abolished (delta pH=−0.005+/−0.01; N=6) by the addition of bovine carbonic anhydrase (5 mg l-1) to the external medium. Addition of the carbonic anhydrase inhibitor acetazolamide (1 mmol l-1) to the water significantly reduced the magnitude of the pH disequilibrium (from −0.133+/−0.03 to −0.063+/−0.02; N=4). However, after correcting for the increased buffering capacity of the water caused by acetazolamide, the acid-base disequilibrium during stopped flow was unaffected by this treatment (control delta [H+]=99.8+/−22.8 micromol l-1; acetazolamide delta [H+]=81.3+/−21.5 micromol l-1). In rainbow trout, expired water displayed an acid-base disequilibrium (delta pH=0.09+/−0.01; N=6) that also was abolished by the application of external carbonic anhydrase (delta pH=0.02+/−0.01).The origin of the expired water acid-base disequilibrium was investigated further in dogfish. Intravascular injection of acetazolamide (40 mg kg-1) to inhibit internal carbonic anhydrase activity non-specifically and thus CO2 excretion significantly diminished the extent of the expired water disequilibrium pH after 30 min (from −0.123+/−0.01 to −0.065+/−0.01; N=6). Selective inhibition of extracellular carbonic anhydrase activity using a low intravascular dose (1.3 mg kg-1) of the inhibitor benzolamide caused a significant reduction in the acid-base disequilibrium after 5 min (from −0.11+/−0.01 to −0.07+/−0. 01; N=14). These results demonstrate that the expired water acid-base disequilibrium originates, at least in part, from excretory CO2 and that extracellular carbonic anhydrase in dogfish may have a significant role in carbon dioxide excretion. However, externally oriented carbonic anhydrase (if present in dogfish) plays no role in catalysing the hydration of the excretory CO2 in water flowing over the gills and thus is unlikely to facilitate CO2 excretion.

scholarly journals Carbonic anhydrase inhibitors modify intracellular pH transients and contractions of rat middle cerebral arteries during CO2/HCO3– fluctuations

2017 ◽  
Vol 38 (3) ◽  
pp. 492-505 ◽  
Author(s):  
Jacob K Rasmussen ◽  
Ebbe Boedtkjer
Keyword(s):  
Carbonic Anhydrase ◽  
Intracellular Ph ◽  
Cerebral Arteries ◽  
Carbonic Anhydrase Activity ◽  
Carbonic Anhydrases ◽  
Intracellular Acidification ◽  
Acid Base ◽  
Surface Ph ◽  
Middle Cerebral Arteries ◽  
Carbonic Anhydrase Inhibition

The CO2/HCO3– buffer minimizes pH changes in response to acid–base loads, HCO3– provides substrate for Na+,HCO3–-cotransporters and Cl–/HCO3–-exchangers, and H+ and HCO3– modify vasomotor responses during acid–base disturbances. We show here that rat middle cerebral arteries express cytosolic, mitochondrial, extracellular, and secreted carbonic anhydrase isoforms that catalyze equilibration of the CO2/HCO3– buffer. Switching from CO2/HCO3–-free to CO2/HCO3–-containing extracellular solution results in initial intracellular acidification due to hydration of CO2 followed by gradual alkalinization due to cellular HCO3– uptake. Carbonic anhydrase inhibition decelerates the initial acidification and attenuates the associated transient vasoconstriction without affecting intracellular pH or artery tone at steady-state. Na+,HCO3–-cotransport and Na+/H+-exchange activity after NH4+-prepulse-induced intracellular acidification are unaffected by carbonic anhydrase inhibition. Extracellular surface pH transients induced by transmembrane NH3 flux are evident under CO2/HCO3–-free conditions but absent when the buffer capacity and apparent H+ mobility increase in the presence of CO2/HCO3– even after the inhibition of carbonic anhydrases. We conclude that (a) intracellular carbonic anhydrase activity accentuates pH transients and vasoconstriction in response to acute elevations of pCO2, (b) CO2/HCO3– minimizes extracellular surface pH transients without requiring carbonic anhydrase activity, and (c) carbonic anhydrases are not rate limiting for acid–base transport across cell membranes during recovery from intracellular acidification.

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