Ca(2+)-independent but voltage-dependent secretion in mammalian dorsal root ganglion neurons.
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.
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Institute of Neuroscience, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai 200031, China.
Zhou
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D000200:Action Potentials / Q000502:physiology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002462:Cell Membrane / Q000502:physiology; D002469:Cell Separation; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D025802:Electric Capacitance; D004558:Electric Stimulation; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism; D018408:Patch-Clamp Techniques; D051381:Rats; D022142:Secretory Vesicles / Q000378:metabolism; D013744:Tetanus Toxin / Q000494:pharmacology
D000779:Anesthetics, Local; D002121:Calcium Channel Blockers; D002614:Chelating Agents; D009479:Neuropeptides; D013744:Tetanus Toxin; D002104:Cadmium; D004533:Egtazic Acid; D000255:Adenosine Triphosphate; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium