Roles of High-Voltage–Activated Calcium Channel Subtypes in a Vertebrate Spinal Locomotor Network
| Autor: | A. El Manira, S. Grillner, Martin A. Wikström, Ansgar Büschges |
|---|---|
| Rok vydání: | 2000 |
| Předmět: |
N-Methylaspartate
P-type calcium channel Calcium Channels L-Type Physiology Nerve net In Vitro Techniques Motor Activity Neurotransmission Synaptic Transmission Membrane Potentials Calcium Channels Q-Type Calcium Channels N-Type Biological Clocks Interneurons medicine Animals Protein Isoforms Swimming Motor Neurons Membrane potential Voltage-dependent calcium channel Chemistry General Neuroscience Calcium channel T-type calcium channel Lampreys Calcium Channels P-Type Calcium Channel Blockers Spinal cord Calcium Channel Agonists medicine.anatomical_structure Spinal Cord Calcium Channels Nerve Net Neuroscience |
| Zdroj: | Journal of Neurophysiology. 84:2758-2766 |
| ISSN: | 1522-1598 0022-3077 |
| Popis: | Lamprey spinal cord neurons possess N-, L-, and P/Q-type high-voltage-activated (HVA) calcium channels. We have analyzed the role of the different HVA calcium channels subtypes in the overall functioning of the spinal locomotor network by monitoring the influence of their specific agonists and antagonists on synaptic transmission and on N-methyl-D-aspartate (NMDA)-elicited fictive locomotion. The N-type calcium channel blocker omega-conotoxin GVIA (omega-CgTx) depressed synaptic transmission from excitatory and inhibitory interneurons. Blocking L-type and P/Q-type calcium channels with nimodipine and omega-agatoxin, respectively, did not affect synaptic transmission. Application of omega-CgTx initially decreased the frequency of the locomotor rhythm, increased the burst duration, and subsequently increased the coefficient of variation and disrupted the motor pattern. These effects were accompanied by a depression of the synaptic drive between neurons in the locomotor network. Blockade of L-type channels by nimodipine also decreased the frequency and increased the duration of the locomotor bursts. Conversely, potentiation of L-type channels increased the frequency of the locomotor activity and decreased the duration of the ventral root bursts. In contrast to blockade of N-type channels, blockade or potentiation of L-type calcium channels had no effect on the stability of the locomotor pattern. The P/Q-type calcium channel blocker omega-agatoxin IVA had little effect on the locomotor frequency or burst duration. The results indicate that rhythm generation in the spinal locomotor network of the lamprey relies on calcium influx through L-type and N-type calcium channels. |
| Databáze: | OpenAIRE |
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