PMID- 10864942
OWN - NLM
STAT- MEDLINE
DCOM- 20000726
LR  - 20191023
IS  - 1529-2401 (Electronic)
IS  - 0270-6474 (Print)
IS  - 0270-6474 (Linking)
VI  - 20
IP  - 13
DP  - 2000 Jul 1
TI  - Excitatory role of the hyperpolarization-activated inward current in phasic and 
      tonic firing of rat supraoptic neurons.
PG  - 4855-63
AB  - The properties and functional roles of the hyperpolarization-activated inward 
      current (I(H)) in magnocellular neurosecretory cells (MNCs) were investigated 
      during sharp microelectrode recordings from supraoptic neurons in superfused 
      explants of rat hypothalamus. Under current clamp, voltage responses to 
      hyperpolarizing current pulses featured depolarizing sags that were abolished by 
      the I(H) blocker ZD 7288. Under voltage clamp, subtraction of current responses 
      to hyperpolarizing steps recorded in the absence and presence of ZD 7288 was used 
      to investigate the properties of I(H). Current-voltage analysis revealed that 
      steady-state I(H) amplitude increases with hyperpolarization, with half-maximal 
      activation of the underlying conductance occurring at -78 mV. The time course of 
      activation of I(H) during hyperpolarizing steps was monoexponential with time 
      constants (100-800 msec) decreasing with hyperpolarization. The effects of ZD 
      7288 on I(H) were slow (tau, approximately 15 min), irreversible, and 
      half-maximal at 1.8 micrometer. When tested on continuously active MNCs, 
      application of 30-60 micrometer ZD 7288 caused a significant reduction in firing 
      rate. In phasically active MNCs, the drug decreased burst duration and intraburst 
      firing frequency and caused an increase in the duration of interburst intervals. 
      These effects were accompanied with a small hyperpolarization of the membrane 
      potential. In contrast, ZD 7288 had no effect on spike duration, on the amplitude 
      of calcium-dependent afterpotentials, or on the frequencies and amplitudes of 
      spontaneous synaptic potentials. These results confirm the presence of I(H) in 
      MNCs of the rat supraoptic nucleus and suggest that the presence of this 
      conductance provides an excitatory drive that contributes to phasic and tonic 
      firing.
FAU - Ghamari-Langroudi, M
AU  - Ghamari-Langroudi M
AD  - Centre for Research in Neuroscience, Montreal General Hospital and McGill 
      University, Montreal, Quebec H3G 1A4, Canada. mdbq@musica.mcgill.ca
FAU - Bourque, C W
AU  - Bourque CW
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - J Neurosci
JT  - The Journal of neuroscience : the official journal of the Society for 
      Neuroscience
JID - 8102140
RN  - 0 (Pyrimidines)
RN  - 133059-99-1 (ICI D2788)
RN  - 4368-28-9 (Tetrodotoxin)
RN  - 66-40-0 (Tetraethylammonium)
SB  - IM
MH  - Animals
MH  - Electric Stimulation
MH  - Kinetics
MH  - Male
MH  - Membrane Potentials/drug effects/physiology
MH  - Neurons/drug effects/*physiology
MH  - Organ Culture Techniques
MH  - Patch-Clamp Techniques
MH  - Pyrimidines/pharmacology
MH  - Rats
MH  - Rats, Long-Evans
MH  - Supraoptic Nucleus/*physiology
MH  - Tetraethylammonium/pharmacology
MH  - Tetrodotoxin/pharmacology
PMC - PMC6772279
EDAT- 2000/06/24 00:00
MHDA- 2000/08/01 00:00
PMCR- 2001/01/01
CRDT- 2000/06/24 00:00
PHST- 2000/06/24 00:00 [pubmed]
PHST- 2000/08/01 00:00 [medline]
PHST- 2000/06/24 00:00 [entrez]
PHST- 2001/01/01 00:00 [pmc-release]
AID - 20/13/4855 [pii]
AID - 4295 [pii]
AID - 10.1523/JNEUROSCI.20-13-04855.2000 [doi]
PST - ppublish
SO  - J Neurosci. 2000 Jul 1;20(13):4855-63. doi: 10.1523/JNEUROSCI.20-13-04855.2000.