MIXED EFFECT OF PICROTOXIN ON GABA DOSE CONDUCTANCE RELATION RECORDED FROM LOBSTER MUSCLE
MIXED EFFECT OF PICROTOXIN ON GABA DOSE CONDUCTANCE RELATION RECORDED FROM LOBSTER MUSCLE
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DOI：
10.1016/0028-3908(78)90095-3
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发表时间：
1978-01-01
影响因子：
4.7
通讯作者：
CONSTANTI, A
中科院分区：
文献类型：
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作者：
CONSTANTI, A
印防己毒素（0.1 μ M-10 μ M）以看似竞争型的方式置换龙虾[Homarus vulgaris]肌肉上的GABA对数剂量/电导曲线，并抑制表观GABA最大值（混合拮抗作用）。这种与真正的非竞争性抑制的偏离通过相对阻断效应对GABA浓度的依赖性、GABA双倒数图的非线性（1/平方根）来反映。Δ GN vs.1/a），以及随着GABA浓度的降低，印防己毒素剂量/效应曲线的位置发生改变。γ-γ的剂量/电导曲线氨基-β-羟丁酸（GABOB）和胍基乙酸（GuAc）以混合抑制方式被印防己毒素取代。荷包牡丹碱（100 μ M）对GABA曲线的抑制与真正的非竞争性拮抗作用一致。提出了一个模型，其中GABA与受体的结合被假定为影响印防己毒素的亲和力，其结合位点。基于该模型的表观拮抗/受体解离常数通过将数据直接代入模型方程来估计。
Picrotoxin (0.1 .mu.M-10 .mu.M) displaced the GABA log-dose/conductance curve on lobster [Homarus vulgaris] muscle in a seemingly competitive-type manner as well as depressing the apparent GABA maximum (mixed antagonism). This deviation from true non-competitive inhibition was reflected by a dependence of the relative blocking effect upon GABA concentration, a non-linearity of the GABA double-reciprocal plot (1/.sqroot..DELTA.GN vs. 1/a) in the presence of picrotoxin and an alteration in position of the picrotoxin dose/effect curve with decreasing GABA concentration. Dose/conductance curves for .gamma.-amino-.beta.-hydroxybutyric acid (GABOB) and guanidoacetic acid (GuAc) were displaced in a mixed inhibitory fashion by picrotoxin. The depression of the GABA curve by bicuculline (100 .mu.M) was consistent with a true non-competitive antagonism. A model is proposed in which binding of GABA to the receptor is assumed to influence the affinity of picrotoxin for its binding-site. The apparent antagonistic/receptor dissociation constants on the basis of this model were estimated by direct substitution of data into the model equation.