首页> 外文期刊>Life sciences >Inhibitory effects of 1,4-DHP antagonists on synaptic GABA release modulated by BAY-K 8644 in mechanically dissociated rat substantia innominata.
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Inhibitory effects of 1,4-DHP antagonists on synaptic GABA release modulated by BAY-K 8644 in mechanically dissociated rat substantia innominata.

机译:1,4-DHP拮抗剂对BAY-K 8644调节的机械分离大鼠无名实突触GABA释放的抑制作用。

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The effects of dihydropyridine (1,4-DHP) agonist and antagonists on miniature inhibitory postsynaptic currents (mIPSCs) were investigated in mechanically dissociated rat substantia innominata neurons attached to native GABAergic presynaptic nerve terminals, namely 'synaptic bouton preparation', using nystatin perforated patch recording mode under voltage-clamp conditions. BAY-K 8644 (BAY-K), an L-type Ca(2+) channel agonist, reversibly and concentration dependently facilitated the GABAergic mIPSC frequency without altering the distribution of current amplitudes. Removal of extracellular Ca(2+) completely suppressed the facilitatory effect of BAY-K on mIPSC frequency. The facilitatory effect of BAY-K on mIPSC frequency was maintained even in the presence of selective N-, P- and Q-type Ca(2+) channel antagonists, such as 3 x 10(-6) M omega-conotoxin-GVIA (omega-CgTX-GVIA), 3 x 10(-8) M omega-agatoxin-IVA (omega-AgTX-IVA) and 3 x 10(-6)M omega-conotoxin-MVIIC (omega-CmTX-MVIIC). However, nicardipine (3 x 10(-6) M) and nimodipine (3 x 10(-6) M), 1,4-DHP antagonists, significantly inhibited the mIPSC frequency enhanced by BAY-K by 37 +/- 5 and 42 +/- 6%, respectively. These results suggest the possible existence of L-type Ca(2+) channels in GABAergic presynaptic nerve terminals.
机译:使用制霉菌素穿孔的贴片在附着于天然GABA能突触前神经末梢的机械解离的大鼠无意识神经元中,研究了二氢吡啶(1,4-DHP)激动剂和拮抗剂对微型抑制突触后电流(mIPSCs)的影响。钳位条件下的记录模式。 BAY-K 8644(BAY-K),一种L型Ca(2+)通道激动剂,可逆地且浓度依赖性地促进了GABAergic mIPSC频率,而没有改变电流振幅的分布。去除细胞外Ca(2+)完全抑制了BAY-K对mIPSC频率的促进作用。即使存在选择性的N-,P-和Q型Ca(2+)通道拮抗剂,例如3 x 10(-6)Mω-conotoxin-GVIA,BAY-K对mIPSC频率的促进作用也得以维持。 (omega-CgTX-GVIA),3 x 10(-8)M omega-agatoxin-IVA(omega-AgTX-IVA)和3 x 10(-6)M omega-conotoxin-MVIIC(omega-CmTX-MVIIC)。但是,1,4-DHP拮抗剂尼卡地平(3 x 10(-6)M)和尼莫地平(3 x 10(-6)M)显着抑制BAY-K增强的mIPSC频率37 +/- 5和分别为42 +/- 6%。这些结果表明在GABA能突触前神经末梢可能存在L型Ca(2+)通道。

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