Expression of Kv1.5 K+ channels in activated microglia in vivo.
We examined the expression of outward rectifier K+ channels in activated microglia in vivo. For this purpose, lipopolysaccharide (LPS, 2 microg) was injected into the cortex near the hippocampal region of rat brains, and K+ channel expression was examined using antibodies against shaker-type K+ channels, Kv1.5 and Kv1.3. OX-42-positive microglia were found around the injection sites from 8 h after the LPS injection and remained there for 3 days. The OX-42-positive microglia expressed Kv1.5 immunoreactivity, and the time course of Kv1.5 expression was closely correlated with that of OX-42. In saline-injected brains, OX-42-positive cells also expressed Kv1.5 immunoreactivity even though far fewer OX-42-positive cells were found. Increase of Kv1.5 expression after LPS injection was also demonstrated by immunoblot analysis. On the other hand, Kv1.3 immunoreactivity was barely detected in OX-42-positive cells over the entire experimental period. The expression of Kv1.5 preceded that of inducible nitric oxide synthase (iNOS), which is a prominent indication of microglial activation. iNOS was not detectable until 12 h, and thereafter it was maintained for 3 days together with Kv1.5 and OX-42. These results suggest that in vivo as well as in vitro activated microglia expressed outward K+ channels and that some of the channels at least are Kv1.5.
Jou
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Department of Pharmacology, Ajou University School of Medicine, Suwon, Korea.
Pyo
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Chung
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Jung
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Gwag
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Joe
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D000818:Animals; D051666:Kv1.5 Potassium Channel; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D017628:Microglia / Q000187:drug effects / Q000378:metabolism*; D008934:Mitogens / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D015221:Potassium Channels / Q000096:biosynthesis*; D024642:Potassium Channels, Voltage-Gated; D051381:Rats; D017207:Rats, Sprague-Dawley
C496983:Kcna5 protein, rat; D051666:Kv1.5 Potassium Channel; D008070:Lipopolysaccharides; D008934:Mitogens; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat