Linked Life Data

2722445

Source:http://linkedlifedata.com/resource/pubmed/id/2722445

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
1989-6-26
pubmed:abstractText
Human nonpigmented ciliary epithelial cells (NPE) were grown in tissue culture after transformation with an origin-defective mutant of SV-40 DNA. In these cells membrane potentials (V) were measured using the microelectrode technique. Addition of 10(-4) M acetylcholine led to a bisphasic voltage response. An immediate, transient hyperpolarization was followed by a sustained depolarization below the steady state level. These responses were irreversibly blocked by 10(-5) M atropine. In Ca2+-free media the initial addition of acetylcholine resulted in an unchanged voltage response. A second application of acetylcholine in Ca2+-free solution evoked only an abortive response of V, and further addition had no effect on V. In the presence of Ca2+ channel blockers (10(-5) M verapamil, 1 mM Co2+) the acetylcholine-induced response of the membrane potential was not changed. The initial hyperpolarization induced by acetylcholine was reduced by 33 +/- 3% (n = 6) in the presence of 2 mM Ba2+ and by 79 +/- 6% (n = 6) in the presence of 1 mM quinidine. Moreover, the amplitude of the hyperpolarization was dependent on the extracellular K+ concentration. With increasing extracellular K+ concentration (and decreasing transmembrane K+ gradient) the acetylcholine-induced hyperpolarization was reduced. To further elucidate the role of Ca2+ in the acetylcholine-induced responses, we measured cytoplasmic Ca2+ activity using the fluorescence of intracellularly trapped Fura-2. Cytoplasmic Ca2+ activity increased immediately and transiently upon addition of acetylcholine. We conclude that acetylcholine transiently hyperpolarizes V in cultured human NPE by activation of K+ channels mediated by mobilization of Ca2+ from intracellular stores.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0146-0404
pubmed:author
pubmed:issnType
Print
pubmed:volume
30
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
890-6
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Effect of acetylcholine on membrane potential of cultured human nonpigmented ciliary epithelial cells.
pubmed:affiliation
Institut für Klinische Physiologie, Klinikum Steglitz, Freien Universität Berlin, Federal Republic of Germany.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't