Optic nerve pH and PO2: the effects of carbonic anhydrase inhibition, and metabolic and respiratory acidosis

We studied the effects of acidosis and carbonic anhydrase inhibition on rectal gland fluid secretion. In the anesthetized dogfish shark, Squalus acanthias, volume expanded by a constant infusion of Ringer solution, fluid formation was halved by severe systemic metabolic and respiratory acidosis (pH approximately 7.10) and carbonic anhydrase inhibition. Mild respiratory acidosis (pH approximately 7.6) equivalent to the measured systemic pH during carbonic anhydrase inhibition was without effect. Inhibition of rectal gland enzyme produced severe glandular acidosis, which is indicated by an increase in gland fluid PCO2 (from 7 to 26 mmHg) and HCO3- (from 1.2 to 2.4 mM) and a decrease in pH (from 6.7 to 6.4). Gland tissue total CO2 dropped from 18 to 11 mmol/kg. These changes occurred despite nearly 50% reduction in fluid formation, O2 consumption, and CO2 output. We propose that carbonic anhydrase facilitates CO2 transfer from sites of metabolism to capillary blood by its conversion to HCO3-. This maintains a tolerable intracellular acid-base milieu during stimulated fluid secretion.

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Roles of gill and red cell carbonic anhydrase in elasmobranch HCO3- and CO2 excretion

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1987.253.3.r450 ◽

1987 ◽

Vol 253 (3) ◽

pp. R450-R458 ◽

Cited By ~ 8

Author(s):

E. R. Swenson ◽

T. H. Maren

Keyword(s):

Carbonic Anhydrase ◽

Respiratory Acidosis ◽

Red Cell ◽

Acid Base ◽

Terrestrial Vertebrates ◽

Carbonic Anhydrase Inhibition ◽

Normal Metabolism ◽

Acid Base Status ◽

Erythrocyte Carbonic Anhydrase ◽

Co2 Elimination

We studied the roles of gill and erythrocyte carbonic anhydrase in normal CO2 transfer (metabolic CO2 elimination) and in HCO3- excretion during metabolic alkalosis in the resting and swimming dogfish shark, Squalus acanthias. Gill carbonic anhydrase was selectively inhibited (greater than 98.5%) by 1 mg/kg benzolamide, which caused no physiologically significant red cell carbonic anhydrase inhibition (approximately 40%). Enzyme in both tissues was inhibited by 30 mg/kg methazolamide (greater than 99%). Both drugs caused equivalent reductions in HCO3- excretion following an infusion of 9 mmol/kg NaHCO3 as measured by the rate of fall in plasma HCO3- and by transfer into seawater. Methazolamide (red cell and gill carbonic anhydrase inhibition) caused a respiratory acidosis in fish with normal acid-base status, whereas benzolamide (gill carbonic anhydrase inhibition) did not. The only effect observed with benzolamide in these fish was a small elevation in plasma HCO3-. These findings, taken together, suggest that red cell carbonic anhydrase is required for normal metabolic CO2 elimination by the gill. Although carbonic anhydrase is located in the respiratory epithelium, it appears to have no quantitative role in transfer of metabolic CO2 to the environment, a pattern similar to all terrestrial vertebrates. However, carbonic anhydrase in the gill is crucial to this organ's function in acid-base regulation, both in the excretion of H+ or HCO3- generated in normal metabolism and in various acid-base disturbances.

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Retinal and optic nerve oxygenation and carbonic anhydrase inhibition

Acta Ophthalmologica ◽

10.1111/j.1755-3768.2009.2463.x ◽

2009 ◽

Vol 87 ◽

pp. 0-0

Author(s):

M LA COUR ◽

E STEFANSSON

Keyword(s):

Optic Nerve ◽

Carbonic Anhydrase ◽

Carbonic Anhydrase Inhibition

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Carbonic anhydrase inhibition, antioxidant activity against alveolar epithelial cells and antibacterial effect against Klebsiella pneumoniae enabled by synthesized silica nanoparticles through laser ablation technique

Life Sciences ◽

10.1016/j.lfs.2021.119032 ◽

2021 ◽

pp. 119032

Author(s):

Na Xu ◽

Wujie Lu ◽

Lijie Meng ◽

Xu Feng ◽

Jingjing Xuan ◽

...

Keyword(s):

Antioxidant Activity ◽

Laser Ablation ◽

Epithelial Cells ◽

Carbonic Anhydrase ◽

Klebsiella Pneumoniae ◽

Antibacterial Effect ◽

Alveolar Epithelial Cells ◽

Alveolar Epithelial ◽

Carbonic Anhydrase Inhibition ◽

Laser Ablation Technique

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Coumaronochromone as antibacterial and carbonic anhydrase inhibitors from Aerva persica (Burm.f.) Merr.: experimental and first-principles approaches

Zeitschrift für Naturforschung C ◽

10.1515/znc-2020-0138 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Muhammad Imran ◽

Ahmad Irfan ◽

Mohammed A. Assiri ◽

Sajjad H. Sumrra ◽

Muhammad Saleem ◽

...

Keyword(s):

Carbonic Anhydrase ◽

First Principles ◽

Molecular Electrostatic Potential ◽

Chemical Constituents ◽

Bacterial Strains ◽

Hirshfeld Analysis ◽

Carbonic Anhydrase Inhibition ◽

Inhibition Studies ◽

Lowest Unoccupied Molecular Orbitals

AbstractThe Aerva plants are exceptionally rich in phytochemicals and possess therapeutics potential. Phytochemical screening shows that Aerva persica (Burm.f.) Merr. contains highest contents i.e., total phenolics, flavonoids, flavonols, tannins, alkaloids, carbohydrates, anthraquinones and glycosides. In-vitro antibacterial and enzymatic (carbonic anhydrase) inhibition studies on methanol extracts of A. persica indicated the presence of biological active constituents within chloroform soluble portions. Investigation in the pure constituents on the chloroform portions of A. persica accomplished by column chromatography, NMR and MS analysis. The bioguided isolation yields four chemical constituents of coumaronochromone family, namely aervin (1-4). These pure chemical entities (1-4) showed significant antibacterial activity in the range of 60.05–79.21 µg/ml against various bacterial strains using ampicillin and ciprofloxacin as standard drugs. The compounds 1-4 showed promising carbonic anhydrase inhibition with IC50 values of 19.01, 18.24, 18.65 and 12.92 µM, respectively, using standard inhibitor acetazolamide. First-principles calculations revealed comprehensive intramolecular charge transfer in the studied compounds 1-4. The spatial distribution of highest occupied and lowest unoccupied molecular orbitals, ionization potential, molecular electrostatic potential and Hirshfeld analysis revealed that these coumaronochromone compounds would be proficient biological active compounds. These pure constituents may be used as a new pharmacophore to treat leaukomia, epilepsy, glaucoma and cystic fibrosis.

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