Cellular mechanisms of Cl- transport in trout gill mitochondrion-rich cells.
We have studied Cl(-) transport mechanisms in freshwater rainbow trout gill mitochondrion-rich (MR) cells using intracellular pH (pH(i)) imaging. Scanning electron microscopy demonstrated maintenance of cellular polarity in isolated MR cells. MR cell subtypes were identified by Na(+) introduction to the bath, and Cl(-) transport mechanisms were subsequently examined. Cl(-)-free exposure resulted in an alkalinization of pH(i) in both MR cell subtypes, which was dependent on HCO(3)(-) in the bath and inhibited by 1 mM DIDS. Recovery of pH(i) from an acidified state in Na(+)-free conditions was also DIDS sensitive. These results are the first functional evidence for Cl(-)/HCO(3)(-) exchangers in fish gill MR cells. A direct switch from NaCl to Cl(-)-free conditions caused a pH(i) acidification in a subset of MR cells, which was enhanced in the absence of HCO(3)(-). The acidification was replaced by an alkalinization when Cl(-) removal was performed in the presence of NPPB (500 microM) or EIPA (500 microM). Finally, we found that the Na(+)-induced alkalinization of pH(i) found in a previous study is inhibited by EIPA. This inhibitor profile's results suggest the presence of a Cl(-)-dependent Na(+)/H(+) exchange mechanism.
Parks
Scott K
SK
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada. skparks@ualberta.ca
Tresguerres
Martin
M
Goss
Greg G
GG
D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D001692:Biological Transport; D016764:Cell Polarity; D027963:Chloride-Bicarbonate Antiporters / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism*; D029941:Fish Proteins / Q000378:metabolism; D005618:Fresh Water; D005880:Gills / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D006863:Hydrogen-Ion Concentration; D049990:Membrane Transport Modulators / Q000494:pharmacology; D008855:Microscopy, Electron, Scanning; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D017686:Oncorhynchus mykiss / Q000378:metabolism*; D012965:Sodium Chloride / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism; D013997:Time Factors
D001639:Bicarbonates; D027963:Chloride-Bicarbonate Antiporters; D002712:Chlorides; D029941:Fish Proteins; D049990:Membrane Transport Modulators; D017923:Sodium-Hydrogen Exchangers; D012965:Sodium Chloride