The involvement of the Ca-dependent K channel and of the KCl co-transport in sickle cell dehydration during cyclic deoxygenation.
We have investigated the mechanisms involved in sickle cell dehydration upon continuous or cyclic deoxygenation: the Ca(2+)-activated K+ channel and the KCl co-transport system. Short-term continuous deoxygenation (1 h) of sickle cells in a Ca(2+)-containing medium promoted a stimulation of the efflux of K+ and cell dehydration. This latter was reduced by the replacement of Ca2+ in the medium by EGTA, but not by addition of [(dihydro-indenyl) oxy] alkanoic acid (DIOA), an inhibitor of the KCl co-transport. During cycles of deoxygenation-reoxygenation, cell dehydration was partly prevented by EGTA and significantly reduced by DIOA only in the presence of Ca2+. The present data support the view that sickle cell dehydration during deoxygenation arises from the stimulation of the Ca(2+)-dependent K+ permeability leading to water loss, whereas during reoxygenation periods, subsequent activation of the KCl co-transport also contributes to cell dehydration.
Apovo
M
M
URA CNRS 1116, Université Paris, Orsay, France.
Beuzard
Y
Y
Galacteros
F
F
Bachir
D
D
Giraud
F
F
D000755:Anemia, Sickle Cell / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology*; D002264:Carboxylic Acids / Q000494:pharmacology; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015687:Cell Hypoxia; D004912:Erythrocytes / Q000378:metabolism; D006801:Humans; D007192:Indenes / Q000494:pharmacology; D051036:Large-Conductance Calcium-Activated Potassium Channels; D008565:Membrane Proteins / Q000378:metabolism*; D009584:Nitrogen; D010100:Oxygen; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000378:metabolism*; D024681:Potassium Channels, Calcium-Activated; D027981:Symporters; D014867:Water; D000096922:K Cl- Cotransporters
D002118:Calcium; D002264:Carboxylic Acids; D002352:Carrier Proteins; D007192:Indenes; D051036:Large-Conductance Calcium-Activated Potassium Channels; D008565:Membrane Proteins; D009584:Nitrogen; D010100:Oxygen; D011188:Potassium; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D027981:Symporters; D014867:Water; D000096922:K Cl- Cotransporters; C059990:((dihydroindenyl)oxy)alkanoic acid