Action d'un inhibiteur de la carboanhydrase,l'acétazolamide,sur l'excitabilité du cortex,du thalamus et du rhinencéphale

Summary The electrical activity induced by stimulation of the cortex, diencephalon and rhinencephalon was studied in the rabbit under the influence of a carbonic anhydrase inhibitor, acetazolamide or Diamox. A significant decrease of the excitability was found in the diencephalon.The rapidity and the electivity of this action, as well as the blood pH variations simultaneously registered, suggest a specific inhibition of cerebral carbonic anhydrase by Diamox, although a participation of the metabolic acidosis cannot be fully excluded.     

Calcifying bacteria and carbonic anhydrase]

Carbonic anhydrase activity was measured on bacteria known for their calcifying power. The results obtained allow us to conclude that carbonic anhydrase is not present in their enzymatic equipment. Nevertheless, the addition of carbonic anhydrase in culture media increases the growth of the cultures and their calcifying power. This result is due to the direct action of the enzyme on the pH of the culture medium. The results obtained could be applied to the mechanism of dental plaque calcification.     

Evidence for the existence of two carbonic anhydrase isozymes in rabbit ciliary body

Two carbonic anhydrase isozymes were found in the rabbit ciliary body. Their isoelectric points were determined to be pH 6.6 and pH 7.4, respectively. The total activity of the higher isoelectric point isozyme was higher than that of the lower isoelectric point isozyme.     

Evidence for the existence of two carbonic anhydrase isozymes in rabbit ciliary body

Summary Two carbonic anhydrase isozymes were found in the rabbit ciliary body. Their isoelectric points were determined to be pH 6.6 and pH 7.4, respectively. The total activity of the higher isoelectric point isozyme was higher than that of the lower isoelectric point isozyme.     

Purification and immobilization of human carbonic anhydrase B by using polyacrylamide gel.

Human erythrocyte carbonic anhydrase B was purified and immobilized in polyacrylamide gel. As compared to the soluble enzyme, the immobilized enzyme was considerably more resistant to heat and sulphanilamide action.     

Action d'un inhibiteur de la carboanhydrase (Diamox) sur le pH de l'humeur aqueuse

Summary In 26 rabbits, the normal pH of the aqueous humor, measured with a glass electrode, was found to be 7.59±0.102. With an improved technique, the corresponding measures on ten other rabbits gave an average value of 7.57±0.043.Three hours after the injection of Diamox, a carbonic anhydrase inhibitor, a significant drop of 0.13 pH units was observed.These effects seem to be dependent on the inhibition of the ciliary body carbonic anhydrase; however there may be some participation of the metabolic acidosis of renal origin. The fall of pH in aqueous humor produced by Diamox is to be correlated with the decrease of potassium concentration previously reported; these facts suggest the hypothesis of a competition between potassium and hydrogen ions in the secretion of aqueous humor.     

Effects of parathyroid hormone and calcitonin on carbonic anhydrase location in osteoclasts of cultured embryonic chick bone

The ultrastructural location of carbonic anhydrase has been examined in osteoclasts of cultured embryonic chick metatarsi. In untreated cultures and in those to which parathyroid hormone (PTH) was added, the enzyme was found in close association with the plasma membrane of the ruffled border. After brief calcitonin treatment (10 min) the ruffled border disappeared and the association of carbonic anhydrase with the plasma membrane was diminished. The results indicate that the hormones employed act directly on embryonic bone to alter osteoclast structure and the intracellular location of carbonic anhydrase.     

Purification and immobilization of human carbonic anhydrase B by using polyacrylamide gel

Summary Human erythrocyte carbonic anhydrase B was purified and immobilized in polyacrylamide gel. As compared to the soluble enzyme, the immobilized enzyme was considerably more resistant to heat and sulphanilamide action.Acknowledgments. I thank Prof. R. L. Brahmachary for providing me all the laboratory facilities to carry out the investigation.     

Fermenthistochemische Untersuchungen am Übergangsepithel verschiedener Säugetiere

Summary Histochemical investigations on enzyme activities in the transitional epithelium showed positive reactions with succinic dehydrogenase, esterase, alkaline phosphatase, acid phosphatase and amylophosphorylase (incl. branching factor). Negative results were drawn from cholinesterase, 5-nucleotidase, glucose-6-phosphatase, and carbonic anhydrase.

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Mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Histochemical localization of carbonic anhydrase in fowl proventriculus

Summary The carbonic anhydrase activity in fowl proventriculus was studied by the histochemical method of Hansson. The activity was observed in the mucose membrane cells and in proventricular gland cells. These results, about which there is disagreement in the literature, are discussed in the text.     

Effects of parathyroid hormone and calcitonin on carbonic anhydrase location in osteoclasts of cultured embryonic chick bone

Summary The ultrastructural location of carbonic anhydrase has been examined in osteoclasts of cultured embryonic chick metatarsi. In untreated cultures and in those to which parathyroid hormone (PTH) was added, the enzyme was found in close association with the plasma membrane of the ruffled border. After brief calcitonin treatment (10 min) the ruffled border disappeared and the association of carbonic anhydrase with the plasma membrane was diminished. The results indicate that the hormones employed act directly on embryonic bone to alter osteoclast structure and the intracellular location of carbonic anhydrase.Acknowledgments. This work was supported by NIH grants DE04345 and AM20374. Dr Cao was a visiting scientist from the Department of Biology, East China Normal University, Shanghai, The Peoples Republic of China. We thank Kathryn Majarwitz for assisting with the morphometric analysis. The PTH was provided by the National Institute of Arthritis, Diabetes, Digestive and Kidney Diseases of the National Institutes of Health, US Department of Health and Human Services.     

Die Wirkung von synthetischem Oxytocin (Syntocinon) und Acetazolamid auf die Ausscheidung von Wasser,Natrium und Kalium

Summary Changes in water, sodium, and potassium excretion following administration of synthetic oxytocin (Syntocinon)—alone or in combination with acetazolamide— resemble the changes that occur after an equivalent dose of neurohypophysial extract containing oxytocin. Since the action of Syntocinon on water and sodium excretion is manifest when carbonic anhydrase in kidney tissue is fully inhibited by acetazolamide, it may be assumed that the mechanism whereby Syntocinon increases sodium excretion is independent of carbonic anhydrase. Oxytocin does not affect ultrafiltration in the glomeruli (Krause ⁴) and would therefore appear to modify the reabsorption or excretion process in the tubuli.     

On the role of carbonic anhydrase in the anticonvulsant effects of triethyltin (TET)

Summary Triethyltin (TET) and acetazolamide (ACTZ) both produce marked anticonvulsant effects as evaluated by the maximal electroshock seizure test. However, the mechanism responsible for the anticonvulsant effect of TET and ACTZ is probably not the same since TET does not inhibit the activity of carbonic anhydrase isozyme C in vitro.This study was supported by NIEHS Toxicology Training grant No. ES07 090, NIOSH grant No. OH07085 and a University of Texas Biomedical Research grant. We wish to thank Rebecca Crenshaw for her excellent technical assistance.     

Increase in the oxygen available to the cerebral cortex after the administration of carbonic anhydrase inhibitors]

Oxygen tension (pO2) in cerebral cortex was measured by polarographic method in unanesthetized rabbits. Intravenous administration (25 mg/kg) of carbonic anhydrase inhibitors (acetazolamide, methazolamide, dichlorphenamide, sulthiame) induced an early important rise of cortical p O2, which is not dependent on increase of p O2 and p CO2 and decrease of pH in arterial blood. High dosage of acetazolamide (250 mg/kg) produced the same effect and did not suppress the increase of cortical p O2 under air-CO2 inhalation. This result suggests that CO2 might act specifically upon cerebral vessels.     

Carbonic anhydrase type II in regenerating retinal pigment epithelium. A histochemical study in the rabbit

Type II carbonic anhydrase (CAII) in the cytoplasm of the retinal pigment epithelium (RPE) may contribute to the transport of water and solutes across the RPE. The activity of this enzyme in RPE during its response to damage, e.g., during regeneration, is therefore of interest in understanding retinal disease. Immuno-histochemistry was used to compare CAII activity of normal RPE and RPE experimentally induced to regenerate. In normal rabbits, the RPE stained intensely with a peroxidase-linked antibody specific for human CAII. Regenerating RPE stained less intensely. Within the regenerating epithelium, staining appeared more intense in mature cells than in immature ones, suggesting that CAII activity gradually returns during RPE regeneration.     

Immunohistochemical localization of carbonic anhydrase C in the rat central nervous system]

With obtention of specific antibodies against isoenzyme C of Rat carbonic anhydrase it was possible to realize an immunohistochemical localisation in central nervous system of Rat. Results showed that this enzyme was mainly localized in cytoplasm of oligodendroglial cells and in low concentration in myelin sheath.     

Inhibition of diuresis in the tsetse fly (Glossina morsitans) by ouabain and acetazolamide.

Acetazolamide and ouabain, metabolic inhibitors which interfere with certain membrane transport systems, reduce the rate of water elimination by male Glossina morsitans morsitans. The results suggest that water is transported across membranes during diuresis and that a ouabain sensitive Na+K+ATPase and an acetazolamide-sensitive carbonic anhydrase are involved in diuresis.     

Reduced carbonic anhydrase and Na−K-ATPase activity in gills of salmonids exposed to aluminium-containing acid water

Summary Exposure of young specimens ofS. salar andS. gairdneri to aluminium concentrations of 200 g/l in water at pH 5 induced reductions of 25–40% in the activity of carbonic anhydrase and Na–K-ATPase in the gills.Fish were generously supplied by Settefiskanlegget A/S, Lundamo and the Research Station for Salmonids, Sunndalsøra.     

Multiple esterase forms in isolated hepatocytes and Kupffer cells of partially hepatectomized rats

Summary The esterase patterns of isolated parenchymal liver cells of rats consisted of 6 bands of enzymatic activity, whereas the patterns of iron-loaded Kupffer cells showed 5 bands. Both patterns become simpler in the early prereplicative period of liver regeneration. During simultaneous replication of DNA, i.e. 24 h after partial liver removal, an additional band of esterase activity appears in patterns of hepatocytes and Kupffer cells. At the moment of maximum hepatocyte mitotic rate, i.e. 36 h after partial hepatectomy, both esterase patterns lose the single band of activity again. 2 or 3 days after surgery the initial esterase patterns in hepatocytes return whereas the patterns of Kupffer cells remain incomplete.