Cl- uptake mechanism in freshwater-adapted tilapia (Oreochromis mossambicus).
In this study, the correlation between Cl(-) influx in freshwater tilapia and various transporters or enzymes, the Cl(-)/HCO(3)(-) exchanger, Na(+),K(+)-ATPase, V-type H(+)-ATPase, and carbonic anhydrase were examined. The inhibitors 2x10(-4) M ouabain (a Na(+),K(+)-ATPase inhibitor), 10(-5) M NEM (a V-type H(+)-ATPase inhibitor), 10(-2) M ACTZ (acetazolamide, a carbonic anhydrase inhibitor), and 6x10(-4) M DIDS (a Cl(-)/HCO(3)(-) exchanger inhibitor) caused 40%, 60%-80%, 40%-60%, and 40%-60% reduction in Cl(-) influx of freshwater tilapia, respectively. The inhibitor 2x10(-4) M ouabain also caused 50%-65% inhibition in gill Na(+),K(+)-ATPase activity. Western blot results showed that protein levels of gill Na(+),K(+)-ATPase, V-type H(+)-ATPase, and carbonic anhydrase in tilapia acclimated in low-Cl(-) freshwater were significantly higher than those acclimated to high-Cl(-) freshwater. Based on these data, we conclude that Na(+),K(+)-ATPase, V-H(+)-ATPase, the Cl(-)/HCO(3)(-) exchanger, and carbonic anhydrase may be involved in the active Cl(-) uptake mechanism in gills of freshwater-adapted tilapia.
Institute of Fisheries Science, National Taiwan University, Taipei, Taiwan, Republic of China.
I-Chi
IC
Chang
Pung-Pung
PP
Hwang
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000086:Acetazolamide / Q000494:pharmacology; D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D015153:Blotting, Western; D002256:Carbonic Anhydrases / Q000378:metabolism; D027963:Chloride-Bicarbonate Antiporters / Q000037:antagonists & inhibitors; D002712:Chlorides / Q000378:metabolism / Q000494:pharmacology*; D005618:Fresh Water; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D005880:Gills / Q000378:metabolism; D008301:Maleimides / Q000494:pharmacology; D008954:Models, Biological; D010042:Ouabain / Q000494:pharmacology; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D017210:Tilapia / Q000378:metabolism* / Q000502:physiology; D013997:Time Factors
D027963:Chloride-Bicarbonate Antiporters; D002712:Chlorides; D008301:Maleimides; D010042:Ouabain; D006180:Proton-Translocating ATPases; D002256:Carbonic Anhydrases; D000254:Sodium-Potassium-Exchanging ATPase; D000086:Acetazolamide; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid