Single K+ channels in embryonic leech ganglion cells.
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 (po) 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 po was Ca2+- and voltage-insensitive. One hundred micron glibenclamide reversibly reduced po. 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.
Frey
G
G
Institut für Neurobiologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf.
Schlue
W
W
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D017952:Ganglia, Invertebrate / Q000166:cytology* / Q000378:metabolism; D015640:Ion Channel Gating / Q000187:drug effects; D007865:Leeches / Q000196:embryology / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000145:classification / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000145:classification / Q000187:drug effects / Q000378:metabolism*
D009419:Nerve Tissue Proteins; D015221:Potassium Channels; D000255:Adenosine Triphosphate; D011188:Potassium