摘要
在這個研究中,我們探討吳茱萸次鹼對神經細胞 NG-108-15 離子電流的影響。利用濃度依賴的方法，我們發現吳茱萸次鹼 (2-100 μM)會抑制delay rectifer K+ current(IK(DR))電流幅度。
吳茱萸次鹼抑制IK(DR) IC50為11 μM。Quinidine及dendrotoxin對於這些細胞中的IK(DR)也具有抑制效果，但E-4031則否。吳茱萸次鹼的存在可以延長 IK(DR)去活化的速率，但對細胞中的IK(DR)早期活化階段沒有影響。受到吳茱萸次鹼(5 μM) 抑制後的回復時間，利用單一指數吻合計算為2.87秒。吳茱萸次鹼存在時也可以觀察到有末端電流 (tail current)的存在。細胞接觸單一離子通道紀錄並顯示出吳茱萸次鹼會抑制離子通道的活性，但沒有改變單一離子通道的電流幅度(amplitude)。為了幫助資料整合，我們提供了吳茱萸次鹼對於IK(DR)影響的定量實驗。然而，吳茱萸次鹼(20 μM)對於細胞L型鈣離子電流並無影響。利用current-clamp的技術觀察，吳茱萸次鹼能夠延長神經細胞 NG-108-15的動作電位。這些結果顯示吳茱萸次鹼是KDR離子通道的阻礙物。其增加動作電位duration的機制可能是阻礙IK(DR)。

Abstract
In the present study, the effects of rutaecarpine on ionic currents of NG108-15 neuronal cells were studied. Rutaecarpine (2-100 μM) suppressed the amplitude of voltage-dependent K+ outward current (IK(DR)) in a concentration-dependent manner. The IC50 value for rutaecarpine-induced inhibition of IK was 11μM. However, rutaecarpine (20 μM) had little effect on L-type Ca2+ current. IK(DR) present in these cells is sensitive to the inhibition by quinidine and dendrotoxin, yet not by E-4031. Rutaecarpine enhanced the rate and extent of IK(DR) inactivation, although it had no effect on the initial activation phase of IK(DR). Recovery from block by rutaecarpine (5 μM) was fitted by a single exponential with a value of 2.87 s. Cell-attached single-channel recordings revealed that rutaecarpine decreased channel activity over the length of the test potential without altering single-channel amplitude. With the aid of binding scheme, a quantitative description of the actions of rutaecarpine on IK(DR) was provided. Under current-clamp configuration, rutaecarpine also prolonged action potential duration in NG108-15 cells without altering other variables of the action potential. The results clearly show that rutaecarpine is a blocker of the KDR channel. The increase in action potential duration induced by rutaecarpine can be
explained mainly by its blocking effects on IK(DR).

目錄

中文摘要…………………………………………………….i
英文摘要……………………………………………………. ii
第一章、 緒論………………………………………………. 1
第二章、 材料與方法………………………………………. 3
第三章、 結果………………………………………………. 7
第四章、 討論………………………………………………. 17
第五章、 參考文獻…………………………………………. 22
圖表……………………………………………………….25

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