| Autor: |
Bornancin, M., Renzis, G., Maetz, J. |
| Zdroj: |
Journal of Comparative Physiology; Jun1977, Vol. 117 Issue 3, p313-322, 10p |
| Abstrakt: |
Freshwater eel gills are notorious for their limited ability to pump chloride. As a result there is a considerable discrepancy between the Na and Cl plasma levels, and plasma HCO and blood pH are relatively high in this species. When eels are kept in tanks aerated with pure oxygen, significant alterations in blood acid-base balance, an increase in plasma pCO and a decrease in blood pH, are observed. In fish studied after 3 weeks hyperoxia, the decrease in blood pH is compensated by an increase in plasma HCO. Such fish exhibit a Cl influx 5 times higher than that observed in normoxic fish. This Cl influx is readily inhibited by addition of SCN to the external medium. An anion-stimulated ATPase activated by HCO and by Cl and inhibited by SCN was recently described in membrane fractions of the gills of Carassius auratus, a fish noted for its high Cl pumping rate. This enzyme is also found in the gills of the eel. While the maximal rates of enzyme activation by HCO and by Cl are similar in Carassius and Anguilla, the affinity of the enzyme for Cl is 25 times higher in Carassius. In the microsomal fraction of the hyperoxic eel gills, the maximal anionstimulated ATPase activity remains unchanged but HCO affinity decreases by 50%, while Cl affinity increases 5 times. Thus some characteristics of this ATPase seem to be closely related to the Cl pump activity exhibited by the gill in fresh water. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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