Journal article
Single-channel K+ currents in Drosophila muscle and their pharmacological block
The Journal of membrane biology, Vol.121(3), pp.237-248
05/1991
DOI: 10.1007/BF01951557
PMID: 1865488
Abstract
Four types of nonvoltage-activated potassium channels in the body-wall muscles of Drosophila third instar larvae have been identified by the patch-clamp technique. Using the inside-out configuration, tetraethylammonium (TEA), Ba2+, and quinidine were applied to the cytoplasmic face of muscle membranes during steady-state channel activation. The four channels could be readily distinguished on the basis of their pharmacological sensitivities and physiological properties. The KST channel was the only type that was activated by stretch. It had a high unitary conductance (100 pS in symmetrical 130/130 mM KCl solution), was blocked by TEA (Kd approximately 35 mM), and was the most sensitive to Ba2+ (complete block at 10(-4) M). A Ca(2+)-activated potassium channel, KCF.72 pS (130/130) mM KCl), was gated open at greater than 10(-8) m Ca2+, was the least sensitive to Ba2+ Kd of approximately 3 mM) and TEA (Kd of approximately 100 mM), and was not affected by quinidine. K2 was a small conductance channel of 11 pS (130/2 KCl, pipette/bath), and was very sensitive to quinidine, being substantially blocked at 0.1 mM. It also exhibited a half block at approximately 0.3 mM Ba2+ and approximately 25 mM TEA. A fourth channel type, K3, was the most sensitive to TEA (half block less than 1 mM). It displayed a partial block to Ba2+ at 10 mM, but no block by 0.1 mM quinidine. The blocking effects of TEA, Ba2+ and quinidine were reversible in all channels studied. The actions of TEA and Ba2+ appeared qualitatively different: in all four channels, TEA reduced the apparent unitary conductance, whereas Ba2+ decreased channel open probability.
Details
- Title: Subtitle
- Single-channel K+ currents in Drosophila muscle and their pharmacological block
- Creators
- M G Gorczyca - Department of Biology, University of Iowa, Iowa City 52242C F Wu
- Resource Type
- Journal article
- Publication Details
- The Journal of membrane biology, Vol.121(3), pp.237-248
- Publisher
- United States
- DOI
- 10.1007/BF01951557
- PMID
- 1865488
- ISSN
- 0022-2631
- eISSN
- 1432-1424
- Grant note
- NS18500 / NINDS NIH HHS NS07247 / NINDS NIH HHS
- Language
- English
- Date published
- 05/1991
- Academic Unit
- Iowa Neuroscience Institute; Biology
- Record Identifier
- 9984070459202771
Metrics
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