Evidence for two-pore domain potassium channels in rat cerebral arteries
Evidence for two-pore domain potassium channels in rat cerebral arteries
复制标题
DOI：
10.1152/ajpheart.01377.2005
复制
发表时间：
2006-08-01
影响因子：
4.8
通讯作者：
Marrelli, Sean P.
中科院分区：
文献类型：
--
作者：
Bryan, Robert M., Jr.;You, Junping;Marrelli, Sean P.
关于血管平滑肌细胞（VSMCs）中双孔结构域K+ (K- 2p)通道的存在和功能知之甚少。已知K-2P通道家族的五个成员可被花生四烯酸（AA）直接激活。本研究的目的是确定1)AA敏感的K2P通道是否在脑VSMCs中表达；2)AA是否通过非典型K+通道增加VSMCs中的K+电流，从而使大鼠大脑中动脉（MCA）扩张。RT-PCR揭示了大鼠MCA中以下aa敏感的K- 2p通道的信息：弱内向流K+ (TWIK-2)、twik相关的K+ （TREK-1和TREK-2）、twik相关的aa刺激K+ (TRAAK)和twik相关的卤代烷抑制K+ (THIK-1)通道中的P结构域串联。然而，在离体VSMCs中，只发现了TWIK-2的信息。Western blot结果显示TWIK-2存在于MCA中，免疫组化进一步证实其存在于VSMCs中。AA （10 - 100 μ M）通过内皮依赖机制使MCAs扩张。10 mM TEA、3 mM 4-氨基吡啶、10 μ M格列本脲或100 μ M Ba2+对环加氧酶、环氧加氧酶或脂加氧酶的抑制或经典K+通道的抑制均不影响aa诱导的扩张。aa诱导的扩张被50 mM K+阻断，表明K+通道参与。AA （10 μ M）使分散的VSMCs全细胞K+电流增加。AA诱导电流不受AA代谢途径抑制剂或经典K+通道阻断的影响。我们得出结论，AA扩张大鼠MCA，并通过非典型K+通道增加VSMCs中的K+电流，该通道可能是K- 2p通道家族的成员。
Little is known about the presence and function of two-pore domain K+ (K-2P) channels in vascular smooth muscle cells (VSMCs). Five members of the K-2P channel family are known to be directly activated by arachidonic acid (AA). The purpose of this study was to determine 1) whether AA-sensitive K2P channels are expressed in cerebral VSMCs and 2) whether AA dilates the rat middle cerebral artery (MCA) by increasing K+ currents in VSMCs via an atypical K+ channel. RT-PCR revealed message for the following AA-sensitive K-2P channels in rat MCA: tandem of P domains in weak inward rectifier K+ (TWIK-2), TWIK-related K+ (TREK-1 and TREK-2), TWIK-related AA-stimulated K+ (TRAAK), and TWIK-related halothane-inhibited K+ (THIK-1) channels. However, in isolated VSMCs, only message for TWIK-2 was found. Western blotting showed that TWIK-2 is present in MCA, and immunohistochemistry further demonstrated its presence in VSMCs. AA (10 - 100 mu M) dilated MCAs through an endotheliumin-dependent mechanism. AA-induced dilation was not affected by inhibition of cyclooxygenase, epoxygenase, or lipoxygenase or inhibition of classical K+ channels with 10 mM TEA, 3 mM 4-aminopyridine, 10 mu M glibenclamide, or 100 mu M Ba2+. AA-induced dilations were blocked by 50 mM K+, indicating involvement of a K+ channel. AA (10 mu M) increased whole cell K+ currents in dispersed cerebral VSMCs. AA-induced currents were not affected by inhibitors of the AA metabolic pathways or blockade of classical K+ channels. We conclude that AA dilates the rat MCA and increases K+ currents in VSMCs via an atypical K+ channel that is likely a member of the K-2P channel family.