Wang L, Ding G, Gu Q, Schwarz W. Single-channel properties of a stretch-sensitive chloride channel in the human mast cell line HMC-1.
EUROPEAN BIOPHYSICS JOURNAL : EBJ 2010;
39:757-67. [PMID:
19823818 PMCID:
PMC2847164 DOI:
10.1007/s00249-009-0542-x]
[Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/25/2009] [Accepted: 09/09/2009] [Indexed: 12/11/2022]
Abstract
A stretch-activated (SA) Cl(-) channel in the plasma membrane of the human mast cell line HMC-1 was identified in outside-out patch-clamp experiments. SA currents, induced by pressure applied to the pipette, exhibited voltage dependence with strong outward rectification (55.1 pS at +100 mV and an about tenfold lower conductance at -100 mV). The probability of the SA channel being open (P (o)) also showed steep outward rectification and pressure dependence. The open-time distribution was fitted with three components with time constants of tau(1o) = 755.1 ms, tau(2o) = 166.4 ms, and tau(3o) = 16.5 ms at +60 mV. The closed-time distribution also required three components with time constants of tau(1c) = 661.6 ms, tau(2c) = 253.2 ms, and tau(3c) = 5.6 ms at +60 mV. Lowering extracellular Cl(-) concentration reduced the conductance, shifted the reversal potential toward chloride reversal potential, and decreased the P (o) at positive potentials. The SA Cl(-) currents were reversibly blocked by the chloride channel blocker 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) but not by (Z)-1-(p-dimethylaminoethoxyphenyl)-1,2-diphenyl-1-butene (tamoxifen). Furthermore, in HMC-1 cells swelling due to osmotic stress, DIDS could inhibit the increase in intracellular [Ca(2+)] and degranulation. We conclude that in the HMC-1 cell line, the SA outward currents are mediated by Cl(-) influx. The SA Cl(-) channel might contribute to mast cell degranulation caused by mechanical stimuli or accelerate membrane fusion during the degranulation process.
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