KATP CHANNEL MODULATION OF BRAINSTEM NEURONS IN HYPOXIA

在过去的5年里，我们专注于旨在了解 脑干神经元对氧剥夺的反应和适应。 我们 结果表明，脑干神经元对缺氧的反应是 与皮层神经元的不同。 在缺氧期间，脑干神经元 增强运动神经元的兴奋性，提高运动神经元的输出， 而皮层神经元的兴奋性降低。 的这种降低 神经元兴奋性可能延迟皮层神经元的损伤，但不是 清楚脑干神经元如何保护自己免受过度 去极化和缺氧损伤。 对此，我们的初步数据 已经表明ATP敏感性K+（Katp）通道的激活发生在 这可能会减弱缺氧引起的去极化 并限制神经元兴奋性的增加 我们认为这是一个 重要的发现，因为它的影响不仅限于脑干 神经元，但也适用于所有具有这些功能的神经元。 渠道 尽管如此，在中枢神经元中的Katp通道调节是不稳定的。 还不太清楚，尤其是在缺氧的时候。 为了确定 这些Katp通道在O2剥夺过程中的作用及其调节 许多细胞溶质和膜因子，我们已经开发出这种 实验提案 将检验三个主要假设：1）缺氧 激活脑干神经元中的Katp通道， 缺氧后这些神经元的功能恢复; 2）Katp的激活 缺氧期间的通道是几个相互作用的结果 胞质和膜因子;和3）Katp通道活性被调节 通过内源性神经递质以G蛋白依赖的方式。 几 将使用的技术包括单通道记录， 细胞贴附膜片，急性分离的全细胞电压钳 神经元，离子选择性离子浓度测量 微电极和脑干切片的细胞内记录。 所有 这些技术目前在我们的实验室中有效。 两组 神经元（舌下神经元和非呼吸神经元在实质 nigra）将用于这些实验，两者都具有高密度 Katp频道 我们相信，我们的研究将产生 重要的新信息，这将有助于我们了解这些 在中枢神经元中，Katp通道在兴奋和缺氧时受到调节。 我们希望这些新的知识将导致更有效的设计 预防或减少缺氧/缺血的治疗策略- 导致脑损伤。

Over the past 5 years, we have focused on studies aiming at understanding the response and adaptation of brainstem neurons to O2 deprivation. Our results have indicated that the response of brainstem neurons to hypoxia is different from that of cortical neurons. During hypoxia, brainstem neurons depolarize and increase their excitability to raise motoneuronal output, while excitability of cortical neurons decreases. This decrease in neuronal excitability may delay injury in cortical neurons, but it is not clear how brainstem neurons protect themselves from excessive depolarization and hypoxic damage. In this regard, our preliminary data have shown that activation of ATP-sensitive K+ (Katp) channels occurs during hypoxia and this may attenuate the hypoxia-induced depolarization and limit the increased neuronal excitability. We believe that this is an important finding as its implications are not limited only to brainstem neurons, but also applied to all neurons that are endowed with these channels. In spite of this, Katp channel regulation in central neurons is not well understood, especially during hypoxia. In order to determine the role of these Katp channels during O2 deprivation and their regulation by a number of cytosolic and membrane factors, we have developed this experimental proposal. Three major hypotheses will be tested: 1) hypoxia activates Katp channels in brainstem neurons and this improves the functional recovery of these neurons post hypoxia; 2) activation of Katp channels during hypoxia is a result of interactive changes in several cytosolic and membrane factors; and 3) Katp channel activity is modulated by endogenous neurotransmitters in a G protein-dependent manner. Several techniques will be used including single channel recordings in excised and cell-attached patches, whole-cell voltage clamp in acutely dissociated neurons, measurements of ionic concentrations with ion-selective microelectrodes and intracellular recordings from brainstem slices. All of these techniques are currently operative in our laboratory. Two groups of neurons (hypoglossal neurons and non-respiratory neurons in the substantia nigra) will be used in these experiments, both of which have a high density of Katp channels. We believe that our proposed studies will yield important new information that will improve our understanding of how these Katp channels are regulated in central neurons at zest and during hypoxia. We wish that this new knowledge will lead to a design of more effective therapeutical strategies in preventing or diminishing hypoxia/ischemia- induced brain injury.