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KMID : 0578319970070050610
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Molecules and Cells
1997 Volume.7 No. 5 p.610 ~ p.614
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Expression and Function of Outward K+ Channels Induced by Lipopolysaccharide in Microglia
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Pyo, Hankyoung
chung, Sungkwon/kou, Ilo/Gwag, Byoungjoo/Joe, Eun-Hye
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Abstract
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Cultured microglia exposed to lipopolysaccharide (LPS) express outward K^(+) currents. These currents are due to the expression of new K^(+) channels detected by antibodies against Kv1.5, a shaker type delayed rectifier. We examined whether the K^(+) currents are involved in microglial activation. The amount of nitrite, converted from nitric oxide (NO), was measured as an indication of microglial activation [Chao, C. C., Hu, S., Molitor, T. W., Shaskan, E. G., and Peterson, P.K.(1992) J. Imunumol. 149, 2730-2741]. Nitrite was detected starting from 24 h after LPS treatment and continuously increased over 4 days. Contrary to this, in the presence of 4-aminopyridine (4-AP, 2 mM), a blocker of outward K^(+) currents, nitrite production was reduced to less than 50%. However, the treatment of 4-AP 24 h after LPS did not reduce nitrite production. Other K^(+) channel blockers haveing a less blocking effect on outward k^(+) currents, such as 5 mM tetraethylammonium(TEA)and 1 mM Cs^(+), had little effect. The presnet study shows that the outward K^(+) channels induced by LPS are immunologically related to Kv1.5 and also suggests that these channels are required for microglial activation, particularly for the initiation of the activation process.
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