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首页> 外文期刊>Journal of Neurophysiology >Persistent Ca2+ current contributes to a prolonged depolarization in Aplysia bag cell neurons.
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Persistent Ca2+ current contributes to a prolonged depolarization in Aplysia bag cell neurons.

机译：持续的Ca2 +电流有助于Aplysia袋细胞神经元的去极化时间延长。

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摘要

Neurons may initiate behavior or store information by translating prior activity into a lengthy change in excitability. For example, brief input to the bag cell neurons of Aplysia results in an approximate 30-min afterdischarge that induces reproduction. Similarly, momentary stimulation of cultured bag cells neurons evokes a prolonged depolarization lasting many minutes. Contributing to this is a voltage-independent cation current activated by Ca(2+) entering during the stimulus. However, the cation current is relatively short-lived, and we hypothesized that a second, voltage-dependent persistent current sustains the prolonged depolarization. In bag cell neurons, the inward voltage-dependent current is carried by Ca(2+); thus we tested for persistent Ca(2+) current in primary culture under voltage clamp. The observed current activated between -40 and -50 mV exhibited a very slow decay, presented a similar magnitude regardless of stimulus duration (10-60 s), and, like the rapid Ca(2+) current, was enhanced when Ba(2+) was the permeant ion. The rapid and persistent Ca(2+) current, but not the cation current, were Ni(2+) sensitive. Consistent with the persistent current contributing to the response, Ni(2+) reduced the amplitude of a prolonged depolarization evoked under current clamp. Finally, protein kinase C activation enhanced the rapid and persistent Ca(2+) current as well as increased the prolonged depolarization when elicited by an action potential-independent stimulus. Thus the prolonged depolarization arises from Ca(2+) influx triggering a cation current, followed by voltage-dependent activation of a persistent Ca(2+) current and is subject to modulation. Such synergy between currents may represent a common means of achieving activity-dependent changes to excitability.
机译：神经元可以通过将先前的活动转化为兴奋性的长期变化来启动行为或存储信息。例如，短暂输入海藻的袋状细胞神经元会导致放电后大约30分钟，从而诱导生殖。类似地，对培养的袋状细胞神经元的瞬时刺激会引起持续数分钟的长时间去极化。促成此作用的是由Ca（2+）在刺激过程中进入激活的电压无关阳离子电流。但是，阳离子电流的寿命相对较短，我们假设第二个依赖电压的持续电流会维持延长的去极化。在袋状细胞神经元中，内向电压依赖性电流由Ca（2+）携带;因此，我们在电压钳制下测试了原代培养中的持久性Ca（2+）电流。观察到的在-40至-50 mV之间激活的电流表现出非常缓慢的衰减，无论刺激持续时间（10-60 s）如何，都呈现相似的幅度，并且像快速的Ca（2+）电流一样，当Ba（2）增强时+）是渗透离子。快速和持久的Ca（2+）电流而不是阳离子电流对Ni（2+）敏感。与持续电流有助于响应一致，Ni（2+）降低了在电流钳制下引起的长时间去极化的幅度。最后，蛋白激酶C激活增强了快速和持久的Ca（2+）电流，并增加了由动作电位无关的刺激引起的延长的去极化作用。因此，长时间的去极化是由Ca（2+）涌入触发阳离子电流，然后是持久性Ca（2+）电流的电压依赖性激活引起的，并受到调制。电流之间的这种协同作用可能代表了实现与活动有关的兴奋性变化的一种常用手段。

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