Voltage-gated, margatoxin-sensitive potassium channels, but not calcium-gated, iberiotoxin-sensitive potassium channels modulate acetylcholine release in rat striatal slices.
We evaluated the effects of iberiotoxin, an inhibitor of Slo-type Ca2+-activated potassium channels and two inhibitors of Shaker-type voltage-gated potassium channels margatoxin and dendrotoxin on acetylcholine outflow in rat striatal slices. An in vitro perfusion with 100 nM margatoxin or dendrotoxin induced a concentration-dependent and tetrodotoxin-sensitive enhancement in spontaneous acetylcholine release. In contrast, a perfusion with iberiotoxin did neither modulate basal, nor electrically- or N-methyl-d-aspartate-induced transmitter release. Therefore, Slo-type Ca2+-activated K+-channels do not seem to contribute significantly to cholinergic neurotransmission within rat striatal slices. As the Kv1.2 subtype represents the only common high affinity binding site of margatoxin and dendrotoxin and the effects of these toxins are not additive, this subtype is suggested to be the channel utilized by margatoxin and dendrotoxin to release acetylcholine in this model.
Fischer
H S
HS
University Hospital, Department of Psychiatry, Innsbruck, Austria.
Saria
A
A
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000502:physiology*; D004546:Elapid Venoms / Q000494:pharmacology; D066298:In Vitro Techniques; D051663:Kv1.2 Potassium Channel; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051036:Large-Conductance Calcium-Activated Potassium Channels; D016202:N-Methylaspartate / Q000494:pharmacology*; D009498:Neurotoxins / Q000494:pharmacology*; D010455:Peptides / Q000494:pharmacology*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D024681:Potassium Channels, Calcium-Activated; D024642:Potassium Channels, Voltage-Gated; D051381:Rats; D012604:Scorpion Venoms / Q000494:pharmacology; D051637:Shaker Superfamily of Potassium Channels
D004546:Elapid Venoms; C496972:Kcna2 protein, rat; C494842:Kcnma1 protein, rat; D051663:Kv1.2 Potassium Channel; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051036:Large-Conductance Calcium-Activated Potassium Channels; D009498:Neurotoxins; D010455:Peptides; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D024642:Potassium Channels, Voltage-Gated; D012604:Scorpion Venoms; D051637:Shaker Superfamily of Potassium Channels; C077910:margatoxin; D016202:N-Methylaspartate; C020273:dendrotoxin; C064719:iberiotoxin; D000109:Acetylcholine