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

The 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 ([Ca]). 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 Role of β-Adrenergic Overstimulation in the Early Stages of Renal Injury.

Background/aims: To assess the possible contribution of the β-adrenergic overstimulation in early stages of renal injury, the present study evaluated, in rats, the effects of the β-adrenoceptor agonist isoproterenol (ISO) on renal function and morphology, as well as the renal mRNA and protein expression of the NADPH oxidase isoform 4 (Nox 4) and subunit p22phox, endoplasmic reticulum (ER) stress, pro-inflammatory, pro-apoptotic and renin-angiotensin system (RAS) components.

Methods: Wistar rats received ISO (0.3 mg.

The effects of angiotensin-(1-7) on the exchanger NHE3 and on [Ca] in the proximal tubules of spontaneously hypertensive rats.

The acute effects of angiotensin-1-7 [ANG-(1-7)] on the reabsorptive bicarbonate flow (J[Formula: see text]) were evaluated using stationary microperfusion in vivo in the proximal tubules of spontaneously hypertensive rats (SHR) and their normotensive controls, Wistar-Kyoto (WKY) rats, using a microelectrode sensitive to H In WKY rats, the control J[Formula: see text] was 2.40 ± 0.10 nmol·cm·s ( = 120); losartan (10 M) or A779 (10 M, a specific Mas antagonist), alone or in combination with losartan, decreased the J[Formula: see text] ANG-(1-7) had biphasic effects on J[Formula: see text]: at 10 M, it inhibited, and at 10, it stimulated the flow.

Dose-dependent effects of angiotensin-(1-7) on the NHE3 exchanger and [Ca(2+)](i) in in vivo proximal tubules.

The acute direct action of angiotensin-(1-7) [ANG-(1-7)] on bicarbonate reabsorption (JHCO(3)(-)) was evaluated by stationary microperfusions on in vivo middle proximal tubules in rats using H ion-sensitive microelectrodes. The control JHCO(3)(-) is 2.82 ± 0.

Action of ANP on the nongenomic dose-dependent biphasic effect of aldosterone on NHE1 in proximal S3 segment.

The rapid (2 min) nongenomic effects of aldosterone (ALDO) and/or spironolactone (MR antagonist), RU 486 (GR antagonist), atrial natriuretic peptide (ANP) and dimethyl-BAPTA (BAPTA) on the intracellular pH recovery rate (pHirr) via NHE1 (basolateral Na⁺/H⁺ exchanger isoform), after the acid load induced by NH₄Cl, and on the cytosolic free calcium concentration ([Ca²⁺](i)) were investigated in the proximal S3 segment isolated from rats, by the probes BCECF-AM and FLUO-4-AM, respectively. The basal pHi was 7.15±0.