Activity-dependent accumulation of Ca2+ in axon and dendrites of the leech Leydig neuron.
We have investigated Ca2+ changes evoked by single action potentials (APs) in axon and dendrites of leech Leydig neurons. Dendritic Ca2+ transients induced by an AP were twice as large as in the axon, and Ca2+ recovery was significantly faster in the dendrites as compared to the axon. The AP-induced Ca2+ transients were blocked by Co2+ and suppressed in Ca2+-free saline, indicating Ca2+ influx through voltage-activated channels. During a train of APs, Ca2+ accumulated significantly more in the axon than in the dendrites. Suppression of the Ca2+ influx changed the shape of the action potential and increased the firing frequency. The results suggest a functional role of Ca2+ influx and Ca2+ accumulation during electrical activity in different neuronal subcompartments.
Lohr
C
C
Abteilung für Allgemeine Zoologie, Universität Kaiserslautern, Postfach 3049, D-67653 Kaiserslautern, Germany.
Beck
A
A
Deitmer
J W
JW
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002490:Central Nervous System / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002614:Chelating Agents / Q000494:pharmacology; D003035:Cobalt / Q000494:pharmacology; D003712:Dendrites / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D005456:Fluorescent Dyes; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007395:Interneurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D007865:Leeches / Q000166:cytology / Q000378:metabolism*; D018613:Microscopy, Confocal; D009930:Organic Chemicals
D015220:Calcium Channels; D002614:Chelating Agents; D005456:Fluorescent Dyes; C403124:Oregon Green BAPTA-dextran; D009930:Organic Chemicals; D003035:Cobalt; D002118:Calcium