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Intracellular Ca2+ dynamics in presympathetic PVN neurons during repetitive firing
Author(s) -
Sonner Patrick M,
Filosa Jessica A,
Stern Javier E
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a471-b
Subject(s) - bursting , neuroscience , depolarization , intracellular , biophysics , chemistry , tonic (physiology) , electrophysiology , nucleus , neuronal firing , patch clamp , neuron , physics , biology , biochemistry
Ca2+ influx during repetitive firing influences a variety of neuronal functions, including feedback effects on firing discharge and activation of Ca2+‐dependent signaling mechanisms. Here, we evaluated the effects of firing activity on intracellular Ca2+ levels [Ca2+]i in presympathetic paraventricular nucleus (PVN) neurons. Simultaneous patch‐clamp recordings and Ca2+ confocal imaging were obtained from PVN‐RVLM neurons loaded with Fluo‐5 in brain slices. Spikes were evoked with depolarizing trains of varying numbers of spikes and frequencies. At a given frequency, peak [Ca2+]i, rise time and half width linearly increased with increasing spike numbers. Moreover, at a given number of spikes, [Ca2+]i monoexponentially increased with increasing spike frequency. Changes in [Ca2+]i amplitude were more pronounced in proximal dendrites as compared to somata, possibly reflecting geometrical differences between these two compartments. Finally, larger [Ca2+]i transients were observed when spikes occurred in bursting rather that tonic mode, supporting a contribution of a low threshold spike (LTS), known to underlie bursting firing in these neurons, to spike‐induced changes in [Ca2+]i. Current studies aim to determine whether [Ca2+]i dynamics during repetitive firing in PVN‐RVLM neurons are altered during hypertension. Supported by NIH RO1 HL68725 (JES).