ATP activates K and Cl channels via purinoceptor-mediated release of Ca2+ in human coronary artery smooth muscle.

Full Abstract

Coronary artery smooth muscle cells express G protein-coupled purinoceptors, and we report here for the first time how receptor activation by extracellular ATP influences cell membrane currents and membrane potential in human cells. ATP (100 microM) stimulated a triphasic change in membrane potential lasting several seconds, which was caused by sequential opening of transient inward and outward conductances. The inward current was carried by Cl- and the outward current by K+, as shown by ion substitution and changes in holding potential. Both currents were independent of the presence of external Ca2+ but were blocked by strong buffering of Ca2+ in the internal solution. The P2u- and P2y-purinoceptor agonists UTP and 2-methylthioadenosine 5'-triphosphate activated similar currents, whereas the P2x-receptor agonist alpha, beta-methyleneadenosine 5'-triphosphate and the P1-receptor agonist adenosine failed to stimulate any whole cell currents. The ATP-activated K+ current was inhibited by iberiotoxin (200 nM), and it was potentiated by the BK channel activator NS-1619 (30 microM). In cell-attached recordings, ATP activated a 230-pS BK channel. In conclusion, ATP acting via P2 purinoceptors stimulated release of Ca2+ from internal stores and transiently activated depolarizing Cl- and hyperpolarizing BK channels in human coronary artery smooth muscle cells.

Author information

Author/s: Strøbaek, D (D); Christophersen, P (P); Dissing, S (S); Olesen, S P (SP);

Affiliation: NeuroSearch A/S, Smedeland, Glostrup, Denmark.

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: The American journal of physiology (Am J Physiol), published in UNITED STATES. (Language: eng)

Reference: 1996-Nov; vol 271 (issue 5 Pt 1) : pp C1463-71

Dates: Created 1997/01/09; Completed 1997/01/09; Revised 2006/11/15;

PMID: 8944628, status: MEDLINE (last retrieved date: 2/18/2009)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MeSH Headings (categories) shown below.

Adenosine Triphosphate - analogs & derivatives; pharmacology
Calcium - metabolism
Cells, Cultured
Chloride Channels - drug effects; physiology
Coronary Vessels - physiology
Egtazic Acid - pharmacology
Humans
Indoles - pharmacology
Kinetics
Membrane Potentials - drug effects

Membrane Potentials - drug effects
Muscle, Smooth, Vascular - physiology
Patch-Clamp Techniques
Potassium Channels - drug effects; physiology
Receptors, Purinergic P2 - drug effects; physiology
Tetraethylammonium
Tetraethylammonium Compounds - pharmacology
Thionucleotides - pharmacology
Time Factors
Uridine Triphosphate - pharmacology

Note: Bold headings indicate primary MeSH headings or qualifiers.

Associated Chemicals: Chloride Channels (0) ; Indoles (0) ; Potassium Channels (0) ; Receptors, Purinergic P2 (0) ; Tetraethylammonium Compounds (0) ; Thionucleotides (0) ; 2-methylthio-ATP (43170-89-4) ; Adenosine Triphosphate (56-65-5) ; paxilline (57186-25-1) ; Uridine Triphosphate (63-39-8) ; Tetraethylammonium (66-40-0) ; Egtazic Acid (67-42-5) ; Calcium (7440-70-2)

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