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首页> 外文期刊>The Journal of Neuroscience: The Official Journal of the Society for Neuroscience >Bidirectional interactions between h-channels and Na+-K+ pumps in mesencephalic trigeminal neurons.
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Bidirectional interactions between h-channels and Na+-K+ pumps in mesencephalic trigeminal neurons.

机译：中脑三叉神经元中h通道与Na + -K +泵之间的双向相互作用。

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摘要

The Na(+)-K(+) pump current (I(p)) and the h-current (I(h)) flowing through hyperpolarization-activated channels (h-channels) participate in generating the resting potential. These two currents are thought to be produced independently. We show here bidirectional interactions between Na(+)-K(+) pumps and h-channels in mesencephalic trigeminal neurons. Activation of I(h) leads to the generation of two types of ouabain-sensitive I(p) with temporal profiles similar to those of instantaneous and slow components of I(h), presumably reflecting Na(+) transients in a restricted cellular space. Moreover, the I(p) activated by instantaneous I(h) can facilitate the subsequent activation of slow I(h). Such counteractive and cooperative interactions were also disclosed by replacing extracellular Na(+) with Li(+), which is permeant through h-channels but does not stimulate the Na(+)-K(+) pump as strongly as Na(+) ions. These observations indicate that the interactions are bidirectional and mediated by Na(+) ions. Also after substitution of extracellular Na(+) with Li(+), the tail I(h) was reduced markedly despite an enhancement of I(h) itself, attributable to a negative shift of the reversal potential for I(h) presumably caused by intracellular accumulation of Li(+) ions. This suggests the presence of a microdomain where the interactions can take place. Thus, the bidirectional interactions between Na(+)-K(+) pumps and h-channels are likely to be mediated by Na(+) microdomain. Consistent with these findings, hyperpolarization-activated and cyclic nucleotide-modulated subunits (HCN1/2) and the Na(+)-K(+) pumpalpha3 isoform were colocalized in plasma membrane of mesencephalic trigeminal neurons having numerous spines.
机译：流过超极化激活通道（h通道）的Na（+）-K（+）泵浦电流（I（p））和h电流（I（h））参与产生静息电位。认为这两个电流是独立产生的。我们在这里显示Na（+）-K（+）泵与中脑三叉神经元中的h通道之间的双向相互作用。 I（h）的激活导致产生两种类型的哇巴因敏感的I（p），其时间分布与I（h）的瞬时和慢速成分相似，大概反映了受限细胞空间中的Na（+）瞬变。此外，瞬时I（h）激活的I（p）可以促进慢速I（h）的后续激活。还公开了通过用Li（+）代替细胞外Na（+）来实现这种反作用和合作相互作用，Li（+）可以通过h通道渗透，但不会像Na（+）那样强烈刺激Na（+）-K（+）泵。离子。这些观察结果表明相互作用是双向的，并由Na（+）离子介导。同样在用Li（+）取代细胞外Na（+）之后，尽管I（h）本身增强，尾部I（h）仍显着减少，这归因于I（h）的逆转电位的负移通过细胞内的Li（+）离子积累。这表明存在可发生相互作用的微区。因此，Na（+）-K（+）泵与h通道之间的双向相互作用很可能是由Na（+）微域介导的。与这些发现相一致，超极化激活和环状核苷酸调节亚基（HCN1 / 2）和Na（+）-K（+）pumpalpha3亚型共定位在具有众多刺的中脑三叉神经元的质膜中。

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