Differential expression of Na+,H(+)-antiporter mRNA in biliary epithelial cells and in hepatocytes.
OBJECTIVE
Amiloride inhibitable Na+,H(+)-exchange has recently been identified and characterized in rat biliary epithelial cells where its activity at low intracellular pH is significantly higher than in hepatocytes.


METHODS
Northern blot and reverse transcription-polymerase chain reaction were used to study the expression of the different Na+,H(+)-antiporter isoforms in isolated biliary epithelial cells and hepatocytes.


RESULTS
The present study demonstrates for the first time the expression of Na+,H(+)-antiporter isoform 1 mRNA in rat biliary epithelial cells. Moreover, steady-state levels of this message were several-fold higher in biliary epithelial cells than in hepatocytes. In addition, the expression of Na+,H(+)-antiporter isoform 2 in bile duct epithelial cell but not hepatocytes could be demonstrated by reverse transcription-polymerase chain reaction.


CONCLUSIONS
The higher expression of Na+,H(+)-antiporter isoform 1 mRNA may indicate a higher rate of synthesis and therefore a higher Na+,H(+)-exchange activity in biliary epithelial cells than in hepatocytes and is entirely compatible with the results of the previous functional studies.
Marti
U
U
Department of Clinical Pharmacology, University of Berne, Switzerland.
Elsing
C
C
Renner
E L
EL
Liechti-Gallati
S
S
Reichen
J
J
D000818:Animals; D001652:Bile Ducts / Q000166:cytology / Q000378:metabolism*; D015152:Blotting, Northern; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008297:Male; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics*; D014158:Transcription, Genetic
D012333:RNA, Messenger; D017923:Sodium-Hydrogen Exchangers; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases