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In recent studies, there has been a re-evaluation of the polarity of Na+/H+ exchange in Madin-Darby canine kidney (MDCK) cells. This study was designed to examine aldosterone actions on basolaterally located Na+/H+ exchange of MDCK cell monolayers grown on permeant filter supports; pHi was analysed in the absence of bicarbonate by using the pH-sensitive fluorescent probe 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein. Pre-exposure of MDCK cells to aldosterone led within 10-20 min to an alkalization of pHi (approximately 0.3 pH unit); this effect is prevented by an addition of dimethylamiloride to the basolateral superfusate. Addition of aldosterone led to stimulation of the basolaterally located Na+/H+ exchange activity (Na(+)-dependent recovery from an acid load); this effect required preincubation (more then 3 min) and was observed at 0.1 nM aldosterone. Pre-exposure (15 min) of MDCK monolayers to phorbol 12-myristate 13-acetate also led to an activation of Na+/H+ exchange; pre-exposure to 8-bromo-cAMP led to inhibition of Na+/H+ exchange activity. An inhibitory effect of aldosterone was observed if Na+/H+ exchange activity was analysed in the presence of aldosterone; the highest inhibitory effects (20%-30%) occurred at concentrations of 5 nM and higher. Aldosterone-dependent inhibition does not require preincubation and is fully reversible; it was only observed at low (20 mM) but not at high Na+ concentrations (130 mM). The data suggest that aldosterone has an instantaneous inhibitory effect on basolaterally located Na+/H+ exchange activity under conditions of low Na+, but stimulates the rate of transport activity upon preincubation under conditions of physiological Na+ concentrations.
S Vilella, and
L Guerra, and
C Helmle-Kolb, and
H Murer
July 1990,
Pflugers Archiv : European journal of physiology,
S Vilella, and
L Guerra, and
C Helmle-Kolb, and
H Murer
January 1993,
The Biochemical journal,
S Vilella, and
L Guerra, and
C Helmle-Kolb, and
H Murer
July 1990,
Pflugers Archiv : European journal of physiology,
S Vilella, and
L Guerra, and
C Helmle-Kolb, and
H Murer
January 1996,
The Journal of clinical investigation,
S Vilella, and
L Guerra, and
C Helmle-Kolb, and
H Murer
June 1993,
The American journal of physiology,
S Vilella, and
L Guerra, and
C Helmle-Kolb, and
H Murer
January 2007,
Traffic (Copenhagen, Denmark),
S Vilella, and
L Guerra, and
C Helmle-Kolb, and
H Murer
July 2016,
Molecular biology of the cell,
S Vilella, and
L Guerra, and
C Helmle-Kolb, and
H Murer
November 1985,
The EMBO journal,
S Vilella, and
L Guerra, and
C Helmle-Kolb, and
H Murer
August 1996,
Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association,
S Vilella, and
L Guerra, and
C Helmle-Kolb, and
H Murer
April 1987,
The Journal of biological chemistry,
