Swelling-activated K fluxes in vascular endothelial cells: volume regulation via K-Cl cotransport and K channels.
K efflux pathways responsible for regulatory volume decrease (RVD) were examined in bovine aortic endothelial cells. Hypotonic swelling produced a rapid and reversible threefold increase in bumetanide-insensitive 86Rb efflux. Swelling-activated 86Rb efflux was inhibited 43% when Cl was replaced with NO3, and this Cl-dependent efflux was inhibited by 1 mM furosemide. Neither Cl replacement nor furosemide inhibited the efflux stimulated by a Ca ionophore (A23187) in isotonic medium. Swelling-activated 86Rb efflux was also inhibited by 4,4'-diisothiocyanostilbene-2,2'-disulfonate but not by dinitrostilbenedisulfonate. Cell swelling induced a volume-regulatory K loss that was incomplete in hypotonic medium but complete and more rapid when bumetanide was added or when cells were swollen isosmotically. K loss in the presence of bumetanide was partially blocked by furosemide. We conclude that two separate swelling-activated K fluxes mediate RVD in aortic endothelial cells: a Cl-dependent, furosemide-sensitive, but bumetanide-insensitive flux that is consistent with K-Cl cotransport, and a Cl-independent efflux that presumably is mediated by K channels.
Perry
P B
PB
Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30322.
O'Neill
W C
WC
D000818:Animals; D002034:Bumetanide / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism*; D002712:Chlorides / Q000378:metabolism; D003470:Culture Media; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D005452:Fluoresceins / Q000378:metabolism; D005456:Fluorescent Dyes; D005665:Furosemide / Q000494:pharmacology; D007038:Hypotonic Solutions; D009995:Osmosis; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism*; D012413:Rubidium / Q000378:metabolism; D027981:Symporters; D000096922:K Cl- Cotransporters
D002034:Bumetanide; D002352:Carrier Proteins; D002712:Chlorides; D003470:Culture Media; D005452:Fluoresceins; D005456:Fluorescent Dyes; D005665:Furosemide; D007038:Hypotonic Solutions; D011188:Potassium; D015221:Potassium Channels; D012413:Rubidium; D027981:Symporters; D000096922:K Cl- Cotransporters; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein