- 學位論文
KMUP-1防止血清素誘發肺動脈鉀離子通道蛋白抑制及血管收縮作用
KMUP-1 Prevents Serotonin-Induced K+ Channel Proteins Inhibition and Vasoconstriction in Pulmonary Artery
摘要
肺高壓為一嚴重的罕見疾病，會造成肺動脈的收縮和血管的重塑作用，使得肺動脈血壓持續的升高，最終可能導致右心室衰竭而死亡。血清素可造成肺血管的收縮，且會使肺動脈平滑肌細胞增生，和形成肺高壓有很密切的關係。位於血管平滑肌上的鉀離子通道可調控細胞膜靜止膜電位，在影響血管收縮上扮演著重要的角色。目前已有研究指出，血清素會抑制鉀離子通道而開啟鈣離子通道，使得細胞內鈣離子濃度 ([Ca2+]i) 上升，引起血管收縮，進而可能造成肺高壓的產生。 在本次的研究當中，我們的研究目標為探討KMUP-1是否能預防血清素造成離體肺血管收縮現象和鉀離子通道的抑制作用，以及其所參與的機轉。肺動脈平滑肌細胞是由大鼠犧牲後培養得來，本實驗所使用的細胞均不超過第六代。細胞置入細胞培養箱中與血清素 (10 μM)、KMUP-1 (1 μM) 和其他試劑作用24小時後進行實驗。 我們觀察血清素對離體肺動脈血管的收縮現象，發現血清素可造成明顯的血管收縮，而KMUP-1可以避免此收縮的反應。加入各種鉀離子通道的抑制劑TEA (10 mM)、4-AP (5 mM) 和paxilline (10 μM) 會阻斷KMUP-1的血管舒張作用，推測KMUP-1可能是藉由活化鉀離子通道，而預防血清素造成的血管收縮反應。此外，血清素會抑制肺動脈平滑肌細胞中的Kv (Kv1.5、Kv2.1) 和BKCa等鉀離子通道蛋白質和表現，而KMUP-1可以防止血清素所造成的抑制作用。同時血清素抑制鉀通道蛋白的作用可以被PKA的活化劑8-Br-cAMP (100 μM) 所減弱，另外PKC的抑制劑chelerythrine (1 μM) 也可預防血清素所抑制的鉀通道蛋白表現，以上結果顯示血清素的作用可能參與抑制cAMP/PKA並活化PKC的路徑。因此由本研究中可以得知，KMUP-1可以預防血清素造成的血管收縮現象和鉀離子通道抑制作用，進而有助於改善肺動脈高血壓。
並列摘要
Serotonin (5-hydroxytryptamine, 5-HT) is a potent pulmonary vasoconstrictor and promotes pulmonary arterial smooth muscle cells (PASMCs) proliferation. K+ channels play an essential role in regulating resting membrane potential and contraction of vascular smooth muscle. Serotonin-induced inhibition of K+ channels could increase the intracellular Ca2+ concentration ([Ca2+]i) in PASMCs and could be a major trigger for pulmonary vasoconstriction and development of pulmonary arterial hypertension (PAH). In this study, we examined the mechanism of action by which KMUP-1 could attenuate the pulmonary vasoconstriction in isolated pulmonary arteries (PAs) and prevent the serotonin-induced K+ channel inhibitory activity in PASMCs. PASMCs were primary cultured from Spraque-Dawley rats and placed in the incubator. PASMCs from passage 3 to 6 were used in this study. Cells were incubated with serotonin (10 μM), KMUP-1 (1 μM) or test agents in the same medium for 24 h. Stimulation of isolated PAs with serotonin induced a significant contractile response and KMUP-1 could prevent it. The various K+ channel inhibitors blocked the effect of vasodilatation of KMUP-1. We suggest that the prevention of KMUP-1 on serotonin-induced contraction might via activation of K+ channels. Additionally, serotonin caused decreases the protein expression and activity of voltage-gated K+ (Kv1.5 and Kv2.1) and large-conductance Ca2+-activated K+ (BKCa) channels in PASMCs. KMUP-1 avoided serotonin-induced decreases in K+ channel proteins. Serotonin-inhibited K+ channel proteins were attenuated by the PKA activator 8-Br-cAMP (100 μM). And a PKC inhibitor chelerythrine (1 μM) enhanced serotonin-inhibited K+ channel proteins. These results indicate that serotonin-inhibited K+ channel might involve the PKA inhibition and PKC activation. In conclusion, KMUP-1 could be used to prevent serotonin-induced K+ channels inhibition and vasoconstriction, which promote the development of PAH.
參考文獻
延伸閱讀
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