Neurotransmitter inhibition of neuronal calcium currents by changes in channel voltage dependence

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摘要：

THE voltage-dependent calcium current of many neurons is depressed by transmitters such as noradrenaline 1-3 , GABA 4-6 and kappa-opiate agonists 7-12 . This modulation probably constitutes a major mechanism of presynaptic inhibition 1,8,12 . Although recent work has implicated GTP-binding proteins in the mechanism of current inhibition 13-19 , it is still unknown how the activation of those proteins alters the operation of the channels. In their initial description of the phenomenon 1 , Dunlap and Fischbach proposed that noradrenaline acts by somehow reducing the number of functions calcium channels in the cell. By contrast with this hypothesis, I have found that inhibition of Ca 2+ current is primarily due to a transmitter-induced change in the voltage-dependence with which channels are opened. Transmitters profoundly alter the voltage-dependence of channel activation, but there is little or no change in the number of functional channels activated by very large depolarizations. There is also little effect on the voltage-dependence of inactivation.

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DOI：

10.1038/340153a0

被引量：

1750

年份：

1989