1997 Fiscal Year Final Research Report Summary
The uptake of lidocaine by Characean cells with nuclear magnetic resonance spectroscopy
| Project/Area Number |
07671655
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Anesthesiology/Resuscitation studies
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| Research Institution | Shiga University of Medical Science |
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Principal Investigator |
NOSAKA Shuichi Shiga University of Medical Science, Anesthesiology, Professor, 医学部, 教授 (80237833)
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| Project Period (FY) |
1995 – 1997
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| Keywords | Chara / plasma membrane / membrane potential / Local anesthetic / electrophysiology / NMR / calcium / channel |
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| Research Abstract |
The Chara internodal cell has an action potential. We have employed nuclear magnetic resonance (NMR) spectroscopy to investigate the uptake of lidocaine by the internodal cells of Chara corallina. One of these cells was incubated in 1mM lidocaine solution. After incubation, one sample was washed with deionized water and placed into the NMR tube. All the NMR measurements were performed on a JEOL GX-270 NMR spectrometer. Local anesthetic, lidocaine was taken up by the internodal cell. The uptake of lidocaine was dependent on extracellular pH.When the cells were incubated in lidocaine solution of pH7.8, the uptake of lidocaine increased significantly compared with those incubated in the solution of pH7.O, in the lidocaine solution of pH7.8 the lidocaine level for the intact cell was found to be much higher than that for the internal fluid squeezed from the cell. 0.3mM CaCI2 reduced the uptake of lidocaine, but it was not significant. 1OmM KCL did not increase the uptake of Ilidocaine. The
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se findings have an agreement with the fact that the concentration of uncharged lidocaine increases depending on extracellular pH.They suggested that lidocaine was distributed mainly in the cell membrane and/or the cell wall and the uncharged lidocaine was primarily important. The bound lidocaine might be related to the change of the conductance after the lidocaine-induced depolarization, When the cells were incubated in lower pH medium and at lower temperature, the uptake of lidocaine did not decrease.
QX-314 depolarized the membrane of the cell at rest. This means that not only the charged form of local anesthetic but also the uncharged form can affect the membrane of the cell, In the Chara plasma membrane the main time course of the excitation followed the early ionic processes. The early ionic processes after reception of stimuli could be separated to 2-5 components, one of which was blocked by 0.5mM Ba^<2+>. We concluded that the K^+ channel opens very early after electrical stimulation. Less
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