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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
2
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pubmed:dateCreated |
1997-10-23
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pubmed:abstractText |
The regulation of A-type K+ current (I(A)) and the single channel underlying I(A) in neonatal rat hypothalamus/brain stem cultured neurons were studied with the use of the patch-clamp technique. I(A) had a threshold of activation between -30 and -25 mV (n = 14). Steady-state inactivation of I(A) occurred between -80 and -70 mV and had a membrane voltage at which I(A) was half-maximum of -52.2 mV (n = 14). The mean values for the activation and inactivation (decay) time constants during a voltage step to +20 mV were 2.1 +/- 0.3 (SE) ms (n = 8) and 13.6 +/- 1.9 ms (n = 8), respectively. Single-channel recordings from outside-out patches revealed A-type K+ channels with voltage-dependent activation, 4-aminopyridine (4-AP) sensitivity, and inactivation kinetics similar to those of I(A). The single-channel conductance obtained from cell-attached patches was 15.8 +/- 1.3 pS (n = 4) in a physiological K+ gradient and 41.2 +/- 3.7 pS (n = 5) in symmetrical 140 mM K+. Angiotensin II (Ang II, 100 nM) reduced peak I(A) by approximately 20% during a voltage step to +20 mV (n = 8). Similarly, Ang II (100 nM) markedly reduced single A-type K+ channel activity by decreasing open probability (n = 4). The actions of Ang II on I(A) and single A-type K+ channels were reversible either by addition of the selective angiotensin type 1 (AT1) receptor antagonist losartan (1 microM) or on washout of the peptide. Thus the activation of AT1 receptors inhibits a tetraethylammonium-chloride-resistant, 4-AP-sensitive I(A) and single A-type K+ channels, and this may underlie some of the actions of Ang II on electrical activity of the brain.
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pubmed:grant | |
pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
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pubmed:month |
Aug
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pubmed:issn |
0022-3077
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:volume |
78
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
1021-9
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pubmed:dateRevised |
2008-11-21
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pubmed:meshHeading |
pubmed-meshheading:9307132-4-Aminopyridine,
pubmed-meshheading:9307132-Action Potentials,
pubmed-meshheading:9307132-Angiotensin II,
pubmed-meshheading:9307132-Animals,
pubmed-meshheading:9307132-Animals, Newborn,
pubmed-meshheading:9307132-Biophysical Phenomena,
pubmed-meshheading:9307132-Biophysics,
pubmed-meshheading:9307132-Brain Stem,
pubmed-meshheading:9307132-Cells, Cultured,
pubmed-meshheading:9307132-Hypothalamus,
pubmed-meshheading:9307132-Membrane Potentials,
pubmed-meshheading:9307132-Neurons,
pubmed-meshheading:9307132-Patch-Clamp Techniques,
pubmed-meshheading:9307132-Potassium Channels,
pubmed-meshheading:9307132-Rats,
pubmed-meshheading:9307132-Rats, Sprague-Dawley
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pubmed:year |
1997
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pubmed:articleTitle |
A-type K+ current in neurons cultured from neonatal rat hypothalamus and brain stem: modulation by angiotensin II.
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pubmed:affiliation |
Department of Physiology, University of Florida College of Medicine, Gainesville 32610, USA.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
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