Single K+ Channels in Embryonic Leech Ganglion Cells |
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Authors: | G Frey W-R Schlue |
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Institution: | Institut für Neurobiologie, Heinrich-Heine-Universit?t Düsseldorf, Universit?tsstr. 1, D-40225 Düsseldorf, DE
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Abstract: | We investigated the properties of single K+ channels in the soma membrane of embryonic leech ganglion cells using the patch-clamp technique. We compared these K+ channels with the K+ channels found previously in Retzius neurons of the adult leech.
In ganglion cells of 9- to 15-day-old embryos we characterized eight different types of K+ channels with mean conductances of 21, 55, 84, 111, 122, 132, 149 and 223 pS.
The 55 pS and 84 pS channels showed flickering and were active for less than 2 min after excising the patch. The 111 pS channel
was an outward rectifier, and the open state probability (p
o
) decreased in the inside-out configuration when the Ca2+ concentration was raised from pCa 7 to pCa 3.
The 122 pS channel also showed outward rectification. This type of channel was activated after changing from the cell-attached
to the inside-out configuration and it did not inactivate during more than 30 min. The p
o
was Ca2+- and voltage-insensitive. One hundred μm glibenclamide reversibly reduced p
o
.
The 132 pS channel was an outward rectifier and was Ca2+-insensitive.
The 149 pS channel inactivated in the inside-out configuration. The 149- and the 223 pS channel showed inward rectification.
The 111 pS channel had similar properties to the Ca2+-dependent K+ channel and the 122 pS channel resembled the ATP-inhibited K+ channel found previously in Retzius neurons of the adult leech.
Received: 20 April 1995/Revised: 18 January 1996 |
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Keywords: | : Patch clamp — Central nervous system — ATP — Ca2+— Glibenclamide |
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