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Regulation Of Apical Nhe3 Trafficking By Ouabain-Induced Activation Of Basolateral Na/K-Atpase Receptor Complex, Haiping Cai, Liang Wu, Weikai Qu, Deepak Malhotra, Zijian Xie, Joseph I. Shapiro, Jiang Liu

Pharmaceutical Science and Research

The long-term effects of ouabain on transepithelial Na⁺ transport involve transcriptional downregulation of apical Na⁺/H⁺ exchanger isoform 3 (NHE3). The aim of this study was to determine whether ouabain could acutely regulate NHE3 via a posttranscriptional mechanism in LLC-PK1 cells. We observed that the basolateral, but not apical, application of ouabain for 1 h significantly reduced transepithelial Na⁺ transport. This effect was not due to changes in the integrity of tight junctions or increases in the intracellular Na⁺ concentration. Ouabain regulated the trafficking of NHE3 and subsequently inhibited its activity, a process independent of …