Expression of mineralocorticoid receptor (MR), glucocorticoid receptor (GR), and Na⁺-K⁺ ATPase subunits in mouse macula densa cell line (NE-MD).

Abstract

The purpose of this study was to examine whether Na⁺-K⁺ ATPase, MR, and major renal Na⁺ transporters expressed in NE-MD cells. It has been proposed that instead of Na⁺-K⁺ ATPase, apical colonic H⁺-K⁺ ATPase in concert with Na⁺-H⁺ exchanger (NHE2) may account for Na⁺ exit from MD cells (Peti-Peterdi et al, 2002). In the present study, expression of Na⁺-K⁺ ATPase subunits and related genes was evaluated by reverse transcription polymerase chain reaction (RT-PCR) in newly established NE-MD cells (Yasuoka et al, 2005). Alpha₁,₃, beta₁,₃ subunits expression was positive, but Alpha₂, beta₂, and gamma (a,b,c) subunits expression was negative. Further, NHE1,2 expression was positive, whereas NHE3,4 expression was negative. MR and GR expression was positive. Moreover, colonic H⁺-K⁺ ATPase was positive, but gastric H⁺-K⁺ ATPase was negative. These data suggest that although colonic H⁺-K⁺ ATPase and NHE2 mRNAs were expressed, Na⁺-K⁺ ATPase may regulate cytosolic [Na⁺] to create a driving force for NaCl entry at the apical membrane in MD cells, and that the gamma subunit may not be essential for functional Na⁺-K⁺ ATPase in the MD. [J Physiol Sci. 2007;57 Suppl:S131]