A swelling-activated chloride current in rat sympathetic neurones.
1. We have tested whether neurones show a swelling-induced Cl- current following hypotonic shock, by recording membrane current responses and cell volume changes in voltage clamped isolated rat sympathetic neurones during application of hypotonic solutions. 2. Using both whole-cell and perforated patch recording methods, hypotonic solution caused cell swelling and the activation of an inward Cl- current at -60 mV. This current showed weak outward rectification with no obvious time dependence. It was inhibited by SITS (0.3-1 mM), NPPB (30-300 microM) and niflumic acid (50-200 microM), but not by tamoxifen (10 microM). 3. Hypotonic solution did not cause a rise in intracellular Ca2+ concentration as measured by simultaneous indo-1 fluorescence. Also, neither the volume change nor Cl- current were affected by the removal of external Ca2+ or internal Ca2+ buffering to < or = 1 nM with EGTA. 4. The Cl- current was unaffected by an inhibitor of protein kinase C (PKC; GF109203X, 3 microM) or by omission of ATP from the pipette solution. 5. Cells exhibited a regulatory volume decrease during sustained exposure to hypotonic solution. This was completely inhibited by 0.5 mM niflumic acid. 6. It is concluded that osmotic swelling induces an outwardly rectifying, Ca2(+)- and PKC-independent Cl- current in these nerve cells. It is suggested that this current may be involved in volume regulatory mechanisms.
Leaney
J L
JL
Department of Pharmacology, University College London, UK. j.leaney@ucl.ac.uk
Marsh
S J
SJ
Brown
D A
DA
D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D048429:Cell Size; D018118:Chloride Channels / Q000037:antagonists & inhibitors; D002712:Chlorides / Q000378:metabolism*; D007038:Hypotonic Solutions; D066298:In Vitro Techniques; D017136:Ion Transport / Q000187:drug effects; D008564:Membrane Potentials; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D009544:Niflumic Acid / Q000494:pharmacology; D009997:Osmotic Pressure; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D017783:Superior Cervical Ganglion / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D013629:Tamoxifen / Q000494:pharmacology
D018118:Chloride Channels; D002712:Chlorides; D007038:Hypotonic Solutions; D013629:Tamoxifen; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D009544:Niflumic Acid; D002118:Calcium