Swelling-activatedCl-currents,I(Cl,swell),weremeasuredduringhyposmoticshockinwhiteLeghornembryonicchickheartcellsusingthewhole-cellrecordingofpatch-clamptechnique.Genistein,aninhibitorofproteintyrosinekinase(PTK),suppressedI(Cl,swell).Underisosmoticconditionphorbol12-myristate13-acetate(PMA),anactivatorofPKC,elicitedtheCl-currentsimilartothatinhyposmoticsolution,whereashyposmoticshockdidnotelicitI(Cl,swell)inchelerythrinechloride(aninhibitorofPKC)-treatedcells.Con-focalmicroscopyexperimentsusingFITC-phalloidinasafluorescentlabelofF-actinshowedthattheactinnetworkwasmovedfromcorticalregionofthecelltothecenterafterhyposmoticshockascomparedwiththeimageunderisosmoticcondition.WhenthecellsweretreatedwithcytochalasinB(CB)orcytochalasinD(CD)underisosmoticconditionthedisruptionoftheF-actinintegritywasobserved,andI(Cl,swell)wasnotelicited.WithcombinationtreatmentofCBwithPMA,hyposmoticsolutioncouldnotelicitedI(Cl,swell).TheresultssuggestedthattheroleofPTK,probablyreceptortyrosinekinase,forregulationofI(Cl,swell)appearedtobeatupstreamsiterelatedtotheroleofF-actin.ThenPKCsignalpathwaywasactivatedsomehowandfinallychangeinthepolymerizationstateofcytoskeletonledtoactivatetheswelling-activatedCl-channels.TheseresultsdemonstrateclearlythatPTK,PKCandF-actinareimportantfactorsforreg-ulationofI(Cl,swell),inembryonicchickheartcellsascomparedwithoftencontroversialresultsreportedindifferentcelltypes.
