Identification of SLC26A transporters involved in the Cl⁻/HCO₃⁻ exchange in proximal tubular cells from WKY and SHR.
OBJECTIVE
slc26a proteins are responsible for a large number of functions either in normal physiology or in human disease. We have previously reported that proximal tubular epithelial (PTE) cells immortalized from spontaneously hypertensive rats (SHRs) were endowed with increased Cl(-)/HCO3(-) exchanger activity and slc26a6 protein expression compared with PTE cells immortalized from normotensive Wistar Kyoto (WKY) rats. The aim of the present study was to identify slc26a members responsible for the Cl(-)/HCO3(-) exchange in WKY and SHR PTE cells.


METHODS
Cl(-)/HCO3(-) exchanger activity was assessed as the initial rate of pHi recovery after removal of HCO3(-) or after removal of Cl(-). The presence of slc26a genes was evaluated by means of reverse transcriptase-PCR (RT-PCR) in WKY and SHR PTE cell lines and in the kidney of WKY and SHR. Transcript abundance was measured by quantitative real-time polymerase chain reaction (PCR).


RESULTS
We detected slc26a4, slc26a6, slc26a7 and slc26a9 transcripts in the rat kidney of WKY and SHR. In WKY and SHR PTE cell lines we detected slc26a4, slc26a6 and slc26a9 transcripts, which were, respectively, 12-, 4- and 15-fold upregulated in SHR cells. Gene silencing with small interfering RNAs (siRNAs) targeting slc26a4, slc26a6 and slc26a9 reduced Cl(-)/HCO3(-) exchanger activity in both cell lines.


CONCLUSIONS
These results indicate that Cl(-)/HCO3(-) exchanger activity is mediated by, at least in part, slc26a4, slc26a6 and slc26a9 in cultured WKY and SHR cells. The overexpression of these slc26a members in SHR cells may correspond to an adaptive process to cope with the sustained increase in proximal tubular sodium reabsorption.
Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, 4200-319 Porto, Portugal.
Sónia
S
Simão
Pedro
P
Gomes
Maria João
MJ
Pinho
Patrício
P
Soares-da-Silva
D000818:Animals; D017920:Antiporters / Q000235:genetics* / Q000378:metabolism; D001639:Bicarbonates / Q000378:metabolism; D001692:Biological Transport; D002478:Cells, Cultured; D027963:Chloride-Bicarbonate Antiporters / Q000235:genetics* / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D000075222:Essential Hypertension; D015870:Gene Expression; D006863:Hydrogen-Ion Concentration; D006973:Hypertension / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D000076988:Sulfate Transporters
D017920:Antiporters; D001639:Bicarbonates; D027963:Chloride-Bicarbonate Antiporters; D002712:Chlorides; C579655:SLC26A6 protein, rat; C494615:Slc26A4 protein, rat; C000589771:Slc26a9 protein, rat; D000076988:Sulfate Transporters
4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; BCECF-AM; Cl(−)/HCO(3)(−) exchanger; EDTA; HEPES; Kidney; NHE; Na(+)/H(+) exchanger; PCR; PT; PTE; Proximal tubular epithelial cells; RT-PCR; SHR; WKY; Wistar Kyoto rat; acetoxymethyl ester of 2′, 7′-bis (carboxyethyl)-5(6)-carboxyfluorescein; ethylenediamine tetraacetic acid; polymerase chain reaction; proximal tubular epithelial; proximal tubule; reverse transcriptase-PCR; siRNA; slc26a family; small interfering RNA; spontaneously hypertensive rat