Evidence against the functional involvement of outwardly rectifying Cl- channels in agonist-induced mast cell exocytosis.
In isolated rat peritoneal mast cells, an outwardly rectifying Cl- channel has been described. Influx of Cl- through this Cl- channel (I(Cl-(OR)) causes hyperpolarization, which facilitates Ca2+ currents through store-operated Ca2+ channels. The exocytotic effect of nerve growth factor (NGF) in the presence of lyso-phosphatidylserine strictly depends on the presence of extracellular [Ca2+]o. The aim of the present study was to assess the importance of I(Cl-(OR)) for exocytosis induced by NGF/lyso-phosphatidylserine. Therefore, we investigated the effects on NGF/lyso-phosphatidylserine-induced exocytosis of [3H]5-hydroxytryptamine ([3H]5-HT) in rat peritoneal mast cells: (a) of two inhibitors of I(Cl-(OR)) (4,4'-diisothiocyanatostilbene2,2'-disulfonic acid [DIDS] and diethylstilbestrol), and (b) of replacement of extracellular Cl- by methylsulfate. Additionally, whole-cell patch-clamp experiments (nystatin-perforated patch) were performed. Diethylstibestrol and DIDS, in concentrations sufficient to abolish the I(Cl-(OR)) (10 microM) and the replacement of (Cl-)o by methylsulfate, were ineffective in impairing the NGF/lyso-phosphatidylserine-induced [3H]5-HT-release. These findings argue against a role of outwardly rectifying Cl- channels in exocytosis induced by NGF/lyso-phosphatidylserine in rat peritoneal mast cells.
Roloff
T
T
Institute of Pharmacology, Hospitalstrasse 4, University of Kiel, D-24105, Kiel, Germany.
Wördehoff
N
N
Ziegler
A
A
Seebeck
J
J
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D004054:Diethylstilbestrol / Q000494:pharmacology; D005089:Exocytosis; D008297:Male; D008407:Mast Cells / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects; D020932:Nerve Growth Factor / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology
D018118:Chloride Channels; D012701:Serotonin; D003189:p-Methoxy-N-methylphenethylamine; D004054:Diethylstilbestrol; D020932:Nerve Growth Factor; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D002118:Calcium