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Biomedical subjects

J MAETZ

Publications and source records attributed to J MAETZ.

At least 19 recordsLinked to original sources
PubMed1964

THE MECHANISM OF SODIUM AND CHLORIDE UPTAKE BY THE GILLS OF A FRESH-WATER FISH, CARASSIUS AURATUS. I. EVIDENCE FOR AN INDEPENDENT UPTAKE OF SODIUM AND CHLORIDE IONS.

Carassius auratus placed in a dilute sodium chloride solution (400 microM) is able to absorb sodium and chloride ions at very different rates, or to absorb one ion and to lose the other. This is the case not only for fish which have been previously kept in choline chloride or sodium sulfate solutions or deionized water, in order to stimulate their absorption processes, but also in control fish which have not been deprived of sodium or chloride. The absorption of sodium or chloride appears to be unaffected by the presence of a nonpermeant co-ion such as choline or sulfate. Conductivity measurements of the external medium show that during ion uptake the conductivity is constant or increases slowly. This suggests the existence of exchange processes between the ions absorbed and endogenous ions excreted. It is unlikely that potassium or calcium is exchanged for sodium, because of the low permeability of the gills to these ions. Finally, the flux ratios observed for both sodium and chloride ions in the present investigation can only be explained, in relation to their electrochemical gradients across the gills, in terms of active transport.

Animals↗
PubMed1964

THE MECHANISM OF SODIUM AND CHLORIDE UPTAKE BY THE GILLS OF A FRESH-WATER FISH, CARASSIUS AURATUS. II. EVIDENCE FOR NH4 ION/NA ION AND HCO3 ION/C1 ION EXCHANGES.

The addition of ammonium ions to the external medium results in an inhibition of the sodium influx and net uptake in Carassius auratus, while intraperitoneal injection of ammonium produces the opposite effect. The simultaneous chloride balance is not significantly affected by these treatments. The addition of bicarbonate ions to the external medium results in a reduction of the influx and net flux of chloride, while injection of bicarbonate produces the opposite effect. The simultaneous sodium balance is not significantly altered. The effects of the external additions are reversible after elimination of the excess ammonium or bicarbonate ions by rinsing. Inhibition of carbonic anhydrase in the gill by injection of acetazoleamide produces a simultaneous inhibition of both sodium and chloride exchanges. These results confirm the hypothesis of an exchange of sodium for ammonium, and of bicarbonate for chloride across the gill. A tentative schematic representation of the ionic absorption mechanisms in the branchial cell of the fresh-water teleosts is given. Similarities with other biological membranes and especially with the renal tubule are pointed out.

Acetazolamide↗