Cl- and regulation of pH by MDCK-C11 cells
Rev. bras. pesqui. méd. biol
; Braz. j. med. biol. res;40(5): 687-696, May 2007. graf, tab
Article
em En
| LILACS
| ID: lil-449084
Biblioteca responsável:
BR1.1
ABSTRACT
The interaction between H+ extrusion via H+-ATPase and Cl- conductance was studied in the C11 clone of MDCK cells, akin to the intercalated cells of the collecting duct. Cell pH (pHi) was measured by fluorescence microscopy using the fluorescein-derived probe BCECF-AM. Control recovery rate measured after a 20 mM NH4Cl acid pulse was 0.136 ± 0.008 pH units/min (dpHi/dt) in Na+ Ringer and 0.032 ± 0.003 in the absence of Na+ (0 Na+). With 0 Na+ plus the Cl- channel inhibitor NPPB (10 æM), recovery was reduced to 0.014 ± 0.001 dpHi/dt. 8-Br-cAMP, known to activate CFTR Cl- channels, increased dpHi/dt in 0 Na+ to 0.061 ± 0.009 and also in the presence of 46 nM concanamycin and 50 æM Schering 28080. Since it is thought that the Cl- dependence of H+-ATPase might be due to its electrogenic nature and the establishment of a +PD (potential difference) across the cell membrane, the effect of 10 æM valinomycin at high (100 mM) K+ was tested in our cells. In Na+ Ringer, dpHi/dt was increased, but no effect was detected in 0 Na+ Ringer in the presence of NPPB, indicating that in intact C11 cells the effect of blocking Cl- channels on dpHi/dt was not due to an adverse electrical gradient. The effect of 100 æM ATP was studied in 0 Na+ Ringer solution; this treatment caused a significant inhibition of dpHi/dt, reversed by 50 æM Bapta. We have shown that H+-ATPase present in MDCK C11 cells depends on Cl- ions and their channels, being regulated by cAMP and ATP, but not by the electrical gradient established by electrogenic H+ transport.
Texto completo:
1
Base de dados:
LILACS
Assunto principal:
ATPases Translocadoras de Prótons
/
Canais de Cloreto
Limite:
Animals
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article
/
Project document