Signaling pathways involved in the rapid biphasic effect of aldosterone on Na+/H+ exchanger in rat proximal tubule cells

Publication date: Available online 24 April 2018Source: The Journal of Steroid Biochemistry and Molecular BiologyAuthor(s): Deise C.A. Leite-Dellova, Shirley J. Szriber, Giovana K.F. Merighe, Juliano Z. Polidoro, Nancy A. Rebouças, Maria Oliveira-Souza, Margarida de Mello-AiresAbstractThe receptors and signaling pathways for nongenomic effects of aldosterone (Aldo) on the proximal Na+/H+ exchanger are still unknown; therefore, the aim of this study was to investigate the mineralocorticoid receptor (MR) and/or glucocorticoid receptor (GR) participation in rapid Aldo effects on NHE1 (basolateral Na+/H+ exchanger isoform) and cytosolic calcium concentration ([Ca2+]i). In addition, phospholipase C (PLC), protein kinase C (PKC), and mitogen-activated protein kinase kinase (MEK) involvement in signaling pathways of such effects was evaluated, using immortalized proximal tubule cells of rat (IRPTC) as an experimental model. MR and GR expression was investigated using reverse transcription polymerase chain reaction and immunoblotting. The intracellular pH recovery rate (after acid loading) and [Ca2+]i were determined by the probes BCECF-AM and FURA 2-AM, respectively. Aldo (10−12 M) promoted a moderate increase in [Ca2+]i and stimulation of NHE1, whereas Aldo (10−6 M) greatly increased the [Ca2+]i, but inhibited the NHE1. BAPTA-AM (a calcium chelator), GR antagonism and inhibition of PLC, PKC and MEK pathway abolished the biphasic and dose-dependent effect of Aldo on NHE1 an...
Source: The Journal of Steroid Biochemistry and Molecular Biology - Category: Biochemistry Source Type: research