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11 - Compounds acting on ion channels
- from Part I - Basic aspects of neurodegeneration
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- By Holger Lerche, Departments of Neurology and Applied Physiology, University of Ulm, Germany, Frank Lehmann-Horn, Departments of Neurology and Applied Physiology, University of Ulm, Germany
- M. Flint Beal, Cornell University, New York, Anthony E. Lang, University of Toronto, Albert C. Ludolph, Universität Ulm, Germany
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- Book:
- Neurodegenerative Diseases
- Published online:
- 04 August 2010
- Print publication:
- 02 June 2005, pp 141-145
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- Chapter
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Summary
Important factors of neuronal death in various diseases ranging from acute illness such as head trauma or stroke to rapidly or slowly progressive disorders such as amyotrophic lateral sclerosis or idiopathic parkinsonism are energy deficit and membrane depolarization. The communication of nerve cells via action potentials and synaptic transmission needs a highly negative resting membrane potential as well as strong transmembrane ionic gradients, which guarantee a regulated ion flow across the membrane. A large part of the energy demand of neurons is therefore required for active ionic pumps such as the Na/K ATPase. A reduction of membrane excitability preventing membrane depolarization and decreasing the transmembrane ionic flow therefore diminishes the energy demand of neurons considerably. The pharmacological modification of the gating of voltage- or ligand-activated ion channels thus provides potentially powerful strategies for neuroprotection. The block of voltage-gated sodium or calcium channels directly reduces the influx of respective ions and decreases excitability, whereas the activation of potassium channels leads to a membrane hyperpolarization reducing excitability and secondarily influx of sodium and calcium through voltage-gated channels and other mechanisms. These neuroprotective strategies, the targets and compounds used for pharmacotherapy and available studies in animal models and humans are discussed in this chapter. The concept of excitoxicity and neuroprotection by its antagonism by a block of glutamate receptors belonging to the group of ligand-gated ion channels is discussed in Chapter 4 of this book.