Linked Life Data

7477959

Source:http://linkedlifedata.com/resource/pubmed/id/7477959

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1995-12-12
pubmed:abstractText
After blockade of the voltage-dependent potassium conductances by intracellular application of 4-aminopyridine and tetraethylammonium in frog myelinated axons, a set of brief (0.1 ms) intracellular depolarizing pulses or a long (200 ms) depolarizing pulse evoked a train of action potentials. Under both experimental conditions a hyperpolarizing afterpotential appeared (duration 367 ms +/- 34, mean +/- S.E., n = 15). The purpose of this study was to investigate the properties of this hyperpolarizing afterpotential. It was found that the hyperpolarizing afterpotential increases in amplitude with: (1) the number of sodium-dependent action potentials; (2) action potential broadening (following potassium channels blockade); and (3) the level of depolarization during a current step. Application of tetrodotoxin prevented the activation of the hyperpolarizing afterpotential by any of the above stimuli. The hyperpolarizing afterpotential was unaffected by: (1) 8-acetyl-strophanthidin, an agent that poisons the electrogenic pumping in the axon; (2) blocking calcium influx with extracellular 10 mM magnesium or 2 mM manganese; and (3) buffering of the intracellular calcium, using EGTA in the recording microelectrode. Extracellular application of tetraethylammonium, but not 4-aminopyridine, reduced the hyperpolarizing afterpotential. The hyperpolarizing afterpotential reversed at >> -92 mV. Increasing the external potassium concentration from 2 to 10 mM shifted the reversal potential +14.5 mV, indicating that the hyperpolarizing afterpotential is a potassium mediated conductance.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0306-4522
pubmed:author
pubmed:issnType
Print
pubmed:volume
68
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
487-95
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
Evidence for a sodium-dependent potassium conductance in frog myelinated axon.
pubmed:affiliation
Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada.
pubmed:publicationType
Journal Article, In Vitro, Research Support, Non-U.S. Gov't