PMID- 9625875
OWN - NLM
STAT- MEDLINE
DCOM- 19980901
LR  - 20240414
IS  - 0022-3751 (Print)
IS  - 1469-7793 (Electronic)
IS  - 0022-3751 (Linking)
VI  - 510 ( Pt 1)
IP  - Pt 1
DP  - 1998 Jul 1
TI  - Caesium blocks depolarizing after-potentials and phasic firing in rat supraoptic 
      neurones.
PG  - 165-75
AB  - 1. The effects of Cs+ on the action potential, post-train after-hyperpolarization 
      (AHP), Ca2+-dependent post-spike depolarizing after-potential (DAP) and phasic 
      firing were examined during intracellular recordings from magnocellular 
      neurosecretory cells (MNCs) in superfused rat hypothalamic explants. 2. 
      Extracellular Cs+ reversibly inhibited (IC50, approximately 1 mM) DAPs, and 
      associated after-discharges, that followed brief spike trains in each of sixteen 
      cells tested. Although bath application of Cs+ also provoked a small reversible 
      depolarization, inhibition of the DAP was retained when membrane voltage was kept 
      constant by current injection. 3. Application of Cs+ had no significant effects 
      on spike duration (n = 8), frequency-dependent spike broadening (n = 8), spike 
      hyperpolarizing after-potentials (n = 14), or the amplitude of the isolated AHP 
      (n = 7). Caesium-evoked inhibition of the DAP, therefore, does not result from 
      diminished spike-evoked Ca2+ influx, and may reflect direct blockade of the 
      conductance underlying the DAP. 4. Inhibition of the DAP was associated with an 
      enhancement of the amplitude and duration of the AHP, indicating that the 
      currents underlying the AHP and the DAP overlap in time following a train of 
      action potentials, and that the relative magnitude of these currents is an 
      important factor in determining the shape and time course of post-train 
      after-potentials. 5. Bath application of Cs+ reversibly abolished phasic firing 
      in each of seven cells tested. This effect was reversible and persisted at all 
      subthreshold voltages tested. These results indicate that the current underlying 
      the DAP is necessary for the genesis of plateau potentials and phasic firing in 
      MNCs.
FAU - Ghamari-Langroudi, M
AU  - Ghamari-Langroudi M
AD  - Centre for Research in Neuroscience, Montreal General Hospital & McGill 
      University, 1650 Cedar Avenue, Montreal, QC, Canada H3G 1A4.
FAU - Bourque, C W
AU  - Bourque CW
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - J Physiol
JT  - The Journal of physiology
JID - 0266262
RN  - 1KSV9V4Y4I (Cesium)
RN  - SY7Q814VUP (Calcium)
SB  - IM
MH  - Animals
MH  - Calcium/physiology
MH  - Cesium/*pharmacology
MH  - Electrophysiology
MH  - Male
MH  - Membrane Potentials/drug effects
MH  - Neurons/*drug effects/*physiology
MH  - Neurosecretory Systems/cytology/physiology
MH  - Rats
MH  - Rats, Inbred Strains
MH  - Reaction Time/drug effects
MH  - Supraoptic Nucleus/cytology/*drug effects/*physiology
PMC - PMC2231010
EDAT- 1998/06/17 00:00
MHDA- 1998/06/17 00:01
PMCR- 1999/07/01
CRDT- 1998/06/17 00:00
PHST- 1998/06/17 00:00 [pubmed]
PHST- 1998/06/17 00:01 [medline]
PHST- 1998/06/17 00:00 [entrez]
PHST- 1999/07/01 00:00 [pmc-release]
AID - 10.1111/j.1469-7793.1998.165bz.x [doi]
PST - ppublish
SO  - J Physiol. 1998 Jul 1;510 ( Pt 1)(Pt 1):165-75. doi: 
      10.1111/j.1469-7793.1998.165bz.x.