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Differential contribution of extracellular and intracellular calcium sources to basal transmission and long‐term potentiation in the sympathetic ganglion of the rat
Author(s) -
Vargas R.,
Cifuentes F.,
Morales M.A.
Publication year - 2007
Publication title -
developmental neurobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.716
H-Index - 129
eISSN - 1932-846X
pISSN - 1932-8451
DOI - 10.1002/dneu.20364
Subject(s) - long term potentiation , extracellular , thapsigargin , ryanodine receptor , biology , intracellular , calcium , neurotransmission , calcium in biology , endocrinology , biophysics , microbiology and biotechnology , medicine , neuroscience , receptor , biochemistry
Abstract Calcium involved in basal ganglionic transmission and long‐term potentiation (LTP) can arise either by influx from the extracellular medium or release from intracellular stores. No attempts have yet been made to concurrently explore the contributions of extracellular and intracellular Ca 2+ to basal ganglionic transmission or LTP. Here, we investigate this subject using the superior cervical ganglion of the rat. To explore the extracellular Ca 2+ contribution, we evaluated basal transmission and LTP at different extracellular Ca 2+ concentrations. To assess intracellular Ca 2+ release, we explored the contribution of the calcium‐induced calcium release process by overactivation or blockade of ryanodine‐sensitive Ca 2+ receptor channel with caffeine, and also by blocking either IP3R with Xestospongin C or the sarco(endo)plasmic reticulum Ca 2+ ‐ATPase pump with thapsigargin. Extracellular Ca 2+ affected ganglionic basal transmission and LTP to different extents. While 25% of the physiological Ca 2+ concentration supported 80% of basal transmission, 50% of normal Ca 2+ was required to achieve 80% of LTP. Notably, disruption of intracellular Ca 2+ release by all the drugs tested apparently did not affect basal ganglionic transmission but impaired LTP. We conclude that basal transmission requires only a small level of Ca 2+ entry, while LTP expression not only requires more Ca 2+ entry but is also dependent on Ca 2+ release from intracellular stores. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007