Whole cell Cl- currents in human neutrophils induced by cell swelling.
The properties of the conductive Cl- transport pathway underlying regulatory volume decrease (RVD) in human neutrophils were investigated using the whole cell patch-clamp technique. Cell swelling was induced during whole cell recordings by making the patch pipette solution hyperosmotic (approximately 20%) relative to the bath by addition of sucrose. Immediately after establishment of the whole cell configuration, no measurable Cl- currents were evident. Over a period of several minutes the outwardly rectifying Cl- current that developed displayed no apparent voltage dependence of activation and did not inactivate with time during voltage steps over the range of -80 to +80 mV. Reduction of Cl- currents by application of suction to the interior of the pipette implied that the swelling-induced Cl- channels are activated by membrane stretch. Based on reversal potential measurements, the volume-induced Cl- conductance was found to discriminate poorly among Cl-, Br-, I-, and NO3-, to possess a finite permeability to glucuronate (Pglucuronate/PCl approximately 0.1) and to be impermeable to cations. Single-channel conductance was estimated to be 1.5 pS from analysis of the variance of membrane current fluctuations. The activated Cl- currents were blocked by 100 microM of the compound MK-447 analogue A (inhibitor constant Ki = 37 microM) and by 200 microM 3,5-diiodosalicylate, 500 microM 4-acetamido-4'-iodothiocyanostilbene-2,2'-disulfonic acid, and 200 microM UK-5099. These results suggest that the initial event triggering RVD in neutrophils may be activation of stretch sensitive Cl- channels in the plasma membrane.
Stoddard
J S
JS
Department of Medicine, Veterans Affairs Medical Center, St. Louis, Missouri.
Steinbach
J H
JH
Simchowitz
L
L
D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D000179:Acrylates / Q000494:pharmacology; D000838:Anions / Q000378:metabolism; D002084:Butylated Hydroxytoluene / Q000031:analogs & derivatives / Q000494:pharmacology; D002712:Chlorides / Q000502:physiology*; D004553:Electric Conductivity; D006801:Humans; D007463:Iodobenzoates; D009504:Neutrophils / Q000166:cytology / Q000378:metabolism* / Q000502:physiology*; D012459:Salicylates / Q000494:pharmacology; D014867:Water / Q000378:metabolism*
D000179:Acrylates; D000838:Anions; D002712:Chlorides; D007463:Iodobenzoates; D012459:Salicylates; D014867:Water; C020891:3,5-diiodosalicylic acid; D002084:Butylated Hydroxytoluene; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; C043654:2-cyano-3-(1-phenylindol-3-yl)acrylate; C013753:2-aminomethyl-4-t-butyl-6-iodophenol