PMID- 9234197
OWN - NLM
STAT- MEDLINE
DCOM- 19970910
LR  - 20190512
IS  - 0022-3751 (Print)
IS  - 1469-7793 (Electronic)
IS  - 0022-3751 (Linking)
VI  - 502 ( Pt 1)
IP  - Pt 1
DP  - 1997 Jul 1
TI  - Outward potassium currents of supraoptic magnocellular neurosecretory cells 
      isolated from the adult guinea-pig.
PG  - 61-74
AB  - 1. Several types of whole-cell outward K+ current recorded from magnocellular 
      neurosecretory cells (MNCs) dissociated from the supraoptic nucleus of the adult 
      guinea-pig were identified on the basis of their voltage dependence, kinetics, 
      pharmacology and Ca2+ dependence. 2. The predominant K+ current evoked from a 
      holding potential of -40 mV was slowly activating, long-lasting, 
      tetraethylammonium (TEA) sensitive and showed little steady-state inactivation. 
      Also, this current was reduced by extracellular Cd2+. These data suggest that in 
      supraoptic MNCs classical Ca(2+)-insensitive, delayed rectifier channels (KV) and 
      Ca(2+)-sensitive, non-inactivating channels (KCa) both contribute to the 
      sustained current. 3. A transient, low-threshold K+ current, which was 
      4-aminopyridine (4-AP) sensitive and showed significant steady-state 
      inactivation, was evoked along with the sustained current from a holding 
      potential of -90 mV. Based on these characteristics, this current corresponds to 
      the A-current (IK(A)) described in other neurons. 4. IK(A) was activated when 
      Ca2+ influx was blocked or when Ca2+ was absent from the extracellular medium, 
      suggesting that Ca2+ influx is not necessary for activation of the current. 5. In 
      many recordings, a transient 4-AP-insensitive outward current was evoked from a 
      holding potential of -40 mV. This high-threshold transient K+ current was 
      abolished by extracellular Cd2+ or TEA and was absent when extracellular Ca2+ was 
      replaced by Sr2+, suggesting that it is a transient Ca(2+)-dependent K+ current. 
      6. We conclude that the presence of multiple types of K+ current may, in part, 
      underlie the complex firing patterns of oxytocinergic and vasopressinergic MNCs.
FAU - Hlubek, M D
AU  - Hlubek MD
AD  - Department of Pharmacology and Toxicology, Michigan State University, East 
      Lansing 48824-1317, USA.
FAU - Cobbett, P
AU  - Cobbett P
LA  - eng
GR  - NS07279/NS/NINDS NIH HHS/United States
GR  - NS28206/NS/NINDS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - England
TA  - J Physiol
JT  - The Journal of physiology
JID - 0266262
RN  - 0 (Potassium Channel Blockers)
RN  - 0 (Potassium Channels)
RN  - 0 (Tetraethylammonium Compounds)
RN  - 00BH33GNGH (Cadmium)
RN  - 66-40-0 (Tetraethylammonium)
RN  - BH3B64OKL9 (4-Aminopyridine)
RN  - RWP5GA015D (Potassium)
RN  - SY7Q814VUP (Calcium)
SB  - IM
MH  - 4-Aminopyridine/pharmacology
MH  - Age Factors
MH  - Animals
MH  - Cadmium/pharmacology
MH  - Calcium/pharmacology
MH  - Electrophysiology
MH  - Guinea Pigs
MH  - Ion Channel Gating/drug effects/physiology
MH  - Kinetics
MH  - Male
MH  - Neurosecretory Systems/*physiology
MH  - Potassium/*metabolism
MH  - Potassium Channel Blockers
MH  - Potassium Channels/physiology
MH  - Supraoptic Nucleus/*cytology/metabolism
MH  - Tetraethylammonium
MH  - Tetraethylammonium Compounds/pharmacology
PMC - PMC1159572
EDAT- 1997/07/01 00:00
MHDA- 1997/07/01 00:01
PMCR- 1997/07/01
CRDT- 1997/07/01 00:00
PHST- 1997/07/01 00:00 [pubmed]
PHST- 1997/07/01 00:01 [medline]
PHST- 1997/07/01 00:00 [entrez]
PHST- 1997/07/01 00:00 [pmc-release]
AID - 10.1111/j.1469-7793.1997.061bl.x [doi]
PST - ppublish
SO  - J Physiol. 1997 Jul 1;502 ( Pt 1)(Pt 1):61-74. doi: 
      10.1111/j.1469-7793.1997.061bl.x.