Dominant role of N-type Ca2+ channels in evoked release of norepinephrine from sympathetic neurons

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作者：

L Hirning，A Fox，E Mccleskey，B Olivera，S Thayer，R Miller，R Tsien

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摘要：

Multiple types of calcium channels have been found in neurons, but uncertainty remains about which ones are involved in stimulus-secretion coupling. Two types of calcium channels in rat sympathetic neurons were described, and their relative importance in controlling norepinephrine release was analyzed. N-type and L-type calcium channels differed in voltage dependence, unitary barium conductance, and pharmacology. Nitrendipine inhibited activity of L-type channels but not N-type channels. Potassium-evoked norepinephrine release was markedly reduced by cadmium and the conesnail peptide toxin omega-Conus geographus toxin VIA, agents that block both N- and L-type channels, but was little affected by nitrendipine at concentrations that strongly reduce calcium influx, as measured by fura-2. Thus N-type calcium channels play a dominant role in the depolarization-evoked release of norepinephrine.

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关键词：

Ganglia, Sympathetic Animals Rats Calcium Norepinephrine Ion Channels Calcium Channel Blockers Membrane Potentials Secretory Rate Electric Conductivity