Evidence for a DIOA-sensitive [K+,Cl-]-cotransport system in cultured vascular smooth muscle cells.
The existence of a [K+,Cl-]-cotransport system in vascular smooth muscle cells was investigated in the A10 cell line by studying the effect of DIOA (dihydroindenyl-oxy-alkanoic acid, a potent inhibitor) on K+, Rb+ and Cl- fluxes. Hypotonic medium (150 mOsm) increased initial rates of ouabain and bumetanide-resistant (OBR) Rb+ uptake by 100%, bumetanide and DIDS-resistant Cl- uptake by 200%, and OBR net K+ efflux by 130%. DIOA inhibited 40 to 100% of the Rb+ influx and net K+ efflux stimulation with an IC50 of 4 X 10(-5) mol/L. DIOA-sensitive Rb+ influx was a sigmoidal function of the decrease in osmolarity, with a threshold at about 230 mOsm. Our results suggest that vascular smooth muscle cells have a DIOA-sensitive [K+,Cl-]-cotransport system. Dissipation of the outwardly directed Cl- gradient with an apparent [Cl- to K+] stoichiometry much higher than one may provide the energy to ensure net KCl (and osmotic water) extrusion and cell volume regulation in these cells.
Saitta
M
M
Institut National de la Santé et de la Recherche Médicale U7/Centre National de la Recherche Scientifique UA 318. Hôpital Necker, Paris, France.
Cavalier
S
S
Garay
R
R
Cragoe
E
E
Hannaert
P
P
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002264:Carboxylic Acids / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D002712:Chlorides / Q000378:metabolism*; D007192:Indenes / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D009994:Osmolar Concentration; D011188:Potassium / Q000378:metabolism*; D012413:Rubidium / Q000378:metabolism; D027981:Symporters; D000096922:K Cl- Cotransporters
D002264:Carboxylic Acids; D002352:Carrier Proteins; D002712:Chlorides; D007192:Indenes; D011188:Potassium; D012413:Rubidium; D027981:Symporters; D000096922:K Cl- Cotransporters; C059990:((dihydroindenyl)oxy)alkanoic acid