Continuing Studies on the Evolution of Ion Channels

这项研究项目将研究水母和扁虫神经元中的离子通道。尽管水母中的神经元的功能与高等动物中的神经元大致相同，但它们至少有一个属性可能反映了它们作为拥有神经系统的最原始动物的进化地位。它们的钠依赖动作电位的生理学与其他动物的钠电流基本相同，但这些电流的药理是钙电流。生物化学和电生理技术将被用来阐明水母神经元中快钠通道的结构。安德森博士还将研究扁虫体内离子通道的多样性和特性。扁虫是第一个拥有集中大脑的动物，因此在神经系统进化中占有重要地位。这些动物是报道的对河豚毒素敏感的最低生物，河豚毒素是一种钠通道阻滞剂。此外，这些动物是寄生虫的一大类，关于它们可兴奋细胞的生理学信息可能会导致新的驱虫药的开发。这项研究将提供神经系统如何进化的重要事实。拥有神经系统的最原始动物的离子通道的生理学和药理学将可以与原始和更高级的动物的通道进行比较。这项研究的结果将通过识别高等动物中具有等价物的离子通道亚型，为一般神经生物学提供有用的信息。

This research project will investigate ion channels in the neurons of the jellyfish and the flatworm. Although neurons in the jellyfish function in much the same way as neurons in higher animals, they have at least one property that may reflect their evolutionary position of being the most primitive animal possessing a nervous system. The physiology of their sodium- dependent action potentials is essentially the same as that of sodium currents of other animals but the pharmacology of those currents is that of calcium currents. Biochemical and electrophysiological techniques will be employed to elucidate the structure of the fast sodium channel in neurons of the jellyfish. Dr. Anderson will also examine the diversity and properties of ion channels in the flatworm. Flatworms are the "first" animals to possess a centralized brain, therefore occupying an significant position in nervous system evolution. These animals are the lowest organism reported of being sensitive to tetrodotoxin, a sodium channel blocker. Furthermore these animals are a major class of parasites and information about the physiology of their excitable cells may lead to the development of new classes of anthelminthic drugs. This study will provide important facts about how nervous systems evolved. The physiology and pharmacology of ion channels in the most primitive animals possessing a nervous system will allow comparisons with channels in primitive and more advanced animals. Results obtained from this study will provide useful information to neurobiology in general by identifying subtypes of ion channels with equivalents in higher animals.