Abstract
We have investigated the Ca(2+) dependence of vesicular secretion from the soma of dorsal root ganglion (DRG) neurons, which secrete neuropeptides by exocytosis of dense-core vesicles. In patch-clamped somata of rat DRG neurons, we found a depolarization-induced membrane capacitance increase (DeltaC(m)) in the absence of extracellular Ca(2+) and in the presence of a Ca(2+) chelator (BAPTA) in the intracellular solution. Depletion of internal Ca(2+) stores by thapsigargin in the Ca(2+)-free bath also did not block the DeltaC(m), indicating that Ca(2+) release from internal Ca(2+) stores may not have been involved. Furthermore, the Ca(2+)-independent DeltaC(m) was blocked by whole-cell dialysis with tetanus toxin and was accompanied by pulsatile secretion of false transmitters, as detected by amperometric measurements. These results indicate the existence of Ca(2+)-independent but voltage-dependent vesicular secretion (CIVDS) in a mammalian sensory neuron.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Action Potentials / physiology
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Adenosine Triphosphate / pharmacology
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Anesthetics, Local / pharmacology
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Animals
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Cadmium / pharmacology
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Calcium / metabolism*
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Calcium Channel Blockers / pharmacology
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Cell Membrane / physiology
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Cell Separation
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Chelating Agents / pharmacology
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Egtazic Acid / analogs & derivatives*
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Egtazic Acid / pharmacology
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Electric Capacitance
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Electric Stimulation
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Exocytosis / drug effects
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Exocytosis / physiology
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Ganglia, Spinal / cytology
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Ganglia, Spinal / drug effects
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Ganglia, Spinal / metabolism*
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Neurons / cytology
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Neurons / drug effects
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Neurons / metabolism*
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Neuropeptides / metabolism
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Patch-Clamp Techniques
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Rats
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Secretory Vesicles / metabolism
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Tetanus Toxin / pharmacology
Substances
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Anesthetics, Local
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Calcium Channel Blockers
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Chelating Agents
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Neuropeptides
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Tetanus Toxin
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Cadmium
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Egtazic Acid
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Adenosine Triphosphate
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1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid
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Calcium