Chloride channels in mast cells: block by DIDS and role in exocytosis.

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Bibliographische Detailangaben
Zeitschriftentitel:	The Journal of general physiology
Personen und Körperschaften:	Dietrich, J, Lindau, M
In:	The Journal of general physiology, 104, 1994, 6, S. 1099-1111
Format:	E-Article
Sprache:	Englisch
veröffentlicht:	Rockefeller University Press
Schlagwörter:	Physiology

Details
Zusammenfassung:	<jats:p>In rat peritoneal mast cells, we have investigated the influence of the chloride transport blocker 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid (DIDS) and the extracellular chloride concentration on the chloride current induced by intracellular application of cyclic AMP (cAMP) and on hexosaminidase secretion from intact cells stimulated with compound 48/80. The inhibition of the Cl-current by extracellular DIDS is voltage and time dependent. Upon depolarization from -10 to +70 mV, the outward current diminishes with millisecond kinetics. The size of the steady state current and the time constant of the decrease both decrease with increasing DIDS concentrations. The steady state current at +70 mV is blocked by DIDS with an IC50 of 2.3 microM. The number of open channels at -10 mV is reduced with an IC50 of 22 microM. The electrophysiological and pharmacological properties of this current are most similar to those of the Cl- current in T lymphocytes activated by osmotic stress (Lewis, R. S., P. E. Ross, and M. D. Cahalan. 1993. Journal of General Physiology. 101:801-826). Extracellular DIDS also inhibits exocytosis. At optimal stimulation with 10 micrograms/ml compound 48/80 secretion is inhibited with an IC50 = 50 microM and a Hill coefficient n = 10. At half optimal stimulation with 1 microgram/ml inhibition occurs with an IC50 = 10 microM and n = 1. Substitution of extracellular chloride by glutamate has only very small effects on secretion stimulated with 10 micrograms/ml compound 48/80. We conclude that activation of the chloride current in mast cells is not essential for stimulation of exocytosis but may enhance secretion at suboptimal stimulation. Alternatively, the channel may play a role in volume regulation following degranulation.</jats:p>
Umfang:	1099-1111
ISSN:	0022-1295 1540-7748
DOI:	10.1085/jgp.104.6.1099