二价阳离子与低浓度河豚毒素下的递质释放
Divalent cations and transmitter release at low concentration of tetrodotoxin.
作者信息
Dascal N, Landau E M, Lass Y
出版信息
Biophys J. 1981 Sep;35(3):573-86. doi: 10.1016/S0006-3495(81)84813-8.
Transmitter release from frog motor terminals was studied in the presence of very low concentrations of tetrodotoxin (TTX, 4.10(-10)--6.10(-9) g/ml). TTX reversibly reduced the amplitude of the end-plate potential (epp), while leaving the amplitude distribution to follow Poisson's law. The effects of a number of divalent cations were studied in the presence of TTX. It was found that after the addition of TTX there was an increase in the constant of dissociation of calcium and strontium from a hypothetical membrane "release site," while the dissociation constants of magnesium and manganese remained unaltered. It is concluded that the release site is probably intracellular and that a reduced presynaptic spike amplitude, as well as magnesium and manganese ions, decrease the access of calcium and strontium to the site.
在极低浓度的河豚毒素（TTX，4×10⁻¹⁰ - 6×10⁻⁹ g/ml）存在的情况下，研究了青蛙运动终板的递质释放。TTX可逆地降低终板电位（epp）的幅度，同时使幅度分布遵循泊松定律。在TTX存在的情况下，研究了多种二价阳离子的作用。发现加入TTX后，钙和锶从假设的膜“释放位点”的解离常数增加，而镁和锰的解离常数保持不变。得出的结论是，释放位点可能在细胞内，并且突触前峰电位幅度的降低以及镁离子和锰离子会减少钙和锶到达该位点的机会。
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