Linked Life Data

1279941

Source:http://linkedlifedata.com/resource/pubmed/id/1279941

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1992-12-7
pubmed:abstractText
The effects of 4-aminopyridine (4-AP) and tetraethylammonium (TEA) on the outward potassium currents in the rapidly and slowly adapting stretch receptor neurons (SRNs) of the crayfish (Pacifastacus leniusculus) were studied using a two micro-electrode voltage-clamp technique. The leakage current was not affected by either 4-AP or TEA. External 4-AP blocked the peak outward current in a dose-dependent manner (1:1 stoichiometry) with an apparent dissociation constant (Kd) of 2.3 +/- 0.2 mM (mean +/- SEM) in the slowly and 1.4 +/- 0.2 mM in the rapidly adapting SRN, the block being voltage dependent. External application of TEA resulted in a block of the steady state current enhancing the transient characteristics of the current response. The block appeared to deviate from a 1:1 stoichiometry and the apparent Kd for TEA was 9.6 +/- 3.4 mM with a cooperativity factor n = 0.43 +/- 0.03 in the slowly adapting SRN and 34.5 +/- 9.2 mM and 0.37 +/- 0.03 respectively in the rapidly adapting SRN. Low Ca2+, apamin and charybdotoxin, which are known to block Ca(2+)-dependent K-currents, had no effects on the outward current as was also the case with catechol. It is concluded that the different effects of TEA and 4-AP on the outward current in the two types of SRNs can be explained by the presence of at least two, probably heteromultimeric, channel populations having similar sensitivity to 4-AP but different sensitivity to TEA. One channel has a high affinity (Kd = 0.8-1.6 mM) for TEA and the other a low affinity (Kd = 173-213 mM) for TEA. The low-affinity channel seems to dominate in the slowly adapting SRN while both channels are equally common in the rapidly adapting SRN. Further, the present results do not support the existence of a macroscopic Ca(2+)-dependent K+ current in the SRNs.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0001-6772
pubmed:author
pubmed:issnType
Print
pubmed:volume
146
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
67-77
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Block of potassium outward currents in the crayfish stretch receptor neurons by 4-aminopyridine, tetraethylammonium chloride and some other chemical substances.
pubmed:affiliation
Department of Physiology II, Karolinska Institute, Stockholm, Sweden.
pubmed:publicationType
Journal Article, In Vitro, Research Support, Non-U.S. Gov't