Na+/K+ pump interacts with the h-current to control bursting activity in central pattern generator neurons of leeches

The dynamics of different ionic currents shape the bursting activity of neurons and networks that control motor output. Despite being ubiquitous in all animal cells, the contribution of the Na+/K+ pump current to such bursting activity has not been well studied. We used monensin, a Na+/H+ antiporter, to examine the role of the pump on the bursting activity of oscillator heart interneurons in leeches. When we stimulated the pump with monensin, the period of these neurons decreased significantly, an effect that was prevented or reversed when the h-current was blocked by Cs+. The decreased period could also occur if the pump was inhibited with strophanthidin or K+-free saline. Our monensin results were reproduced in model, which explains the pump’s contributions to bursting activity based on Na+ dynamics. Our results indicate that a dynamically oscillating pump current that interacts with the h-current can regulate the bursting activity of neurons and networks.

不同离子流的动力学特性塑造了控制运动输出的神经元及神经元网络的爆发式活动。尽管钠钾泵（Na+/K+ pump）流普遍存在于所有动物细胞中，但针对其对这类爆发式活动的贡献尚未得到充分研究。我们利用莫能菌素——一种钠氢反向转运体（Na+/H+ antiporter）——来探究该泵对水蛭心脏振荡中间神经元爆发式活动的调控作用。当我们通过莫能菌素激活该泵时，这些神经元的放电周期显著缩短；若使用铯离子（Cs+）阻断H电流（h-current），则可阻止这一效应或使其逆转。若使用毒毛旋花子苷元或无钾生理盐水抑制该泵，同样可观察到周期缩短的现象。我们在模型中复现了莫能菌素相关的实验结果，该结果基于钠离子动力学阐释了钠钾泵对爆发式活动的调控机制。我们的研究结果表明，与H电流相互作用的动态振荡泵流可调控神经元及神经元网络的爆发式活动。