ISSN:
1432-2013
Keywords:
MDCK-cells
;
Aldosterone
;
Na+/H+ exchange
;
Cl−/HCO 3 − exchange
;
Intercalated cells
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Experiments in dome epithelium of Madin-Darby canine kidney (MDCK) cells were performed to elucidate aldosterone action on acid-base transport. By means of pH-sensitive microelectrodes the pH of the dome fluid was measured while the apical plasma membrane was superfused. In the absence of HCO 3 − the dome fluid (facing the basolateral cell membrane) alkalinized in response to 10−7 mol/l aldosterone. Amiloride (10−3 mol/l) inhibited dome formation and pH recovery of the dome fluid from an extracellular acid load. In the presence of HCO 3 − dome fluid acidified in response to aldosterone. The stilbene derivative diisothiocyanate-stilbene-2,2′-disulphonic acid (DIDS) or removal of Cl− from the apical perfusate inhibited this dome acidification. In aldosterone-depleted MDCK monolayers HCO 3 − was actively accumulated in the dome fluid in contrast to aldosterone-supplemented cells. The results indicate that aldosterone stimulates both amiloride-sensitive Na+/H+ exchange and DIDS-sensitive Cl−/HCO 3 − exchange in the apical cell membrane of MDCK cells. In the absence of aldosterone the HCO 3 − extrusion process is localized in the basolateral membrane in series with apical Na+/H+ exchange, while in the presence of aldosterone Cl−/HCO 3 − is mainly localized in the apical membrane in parallel with Na+/H+ exchange. Cl− exits the cell through apical Cl− channels and is absorbed via the paracellular route.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00382686
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