Larger transient outward K(+) current and shorter action potential duration in Galpha(11) mutant mice. 2010

Michael Wagner, and Elena Rudakova, and Vera Schütz, and Magdalena Frank, and Heimo Ehmke, and Tilmann Volk
Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstrasse 6, 91054, Erlangen, Germany.

The alpha(1)-adrenoceptor as well as the AT(1)- and the ET(A)-receptor couple to G-proteins of the Galpha(q/11) family and contribute to the regulation of the transient outward K(+) current (I(to,f)) under pathological conditions such as cardiac hypertrophy or failure. This suggests an important role of Galpha(q/11)-signalling in the physiological regulation of I(to,f). Here, we investigate mice deficient of the Galpha(11) protein (gna11(-/-)) to clarify the physiological role of Galpha(11) signalling in cardiac ion channel regulation. Myocytes from endocardial and epicardial layers were isolated from the left ventricular free wall and investigated using the ruptured-patch whole-cell patch-clamp technique. At +40 mV, epicardial myocytes from gna11(-/-) mice displayed a 23% larger I(to,f) than controls (52.6 + or - 4.1 pApF(-1), n = 20 vs 42.7 + or - 2.8 pApF(-1), n = 26, p < 0.05). Endocardial I(to,f) was similar in gna11(-/-) mice and controls. With the except of minor changes in endocardial myocytes, I(to,f) kinetics were similar in both groups. In the epicardial layer, western blot analysis revealed a 19% higher expression of the K(+)-channel alpha-subunit Kv4.2 in gna11(-/-) mice than in wild type (wt; p < 0.05). The beta-subunit KChIP2b was upregulated by 102% in epicardial myocytes of gna11(-/-) mice (p < 0.01, n = 4). Consistent with the difference in I(to,f), action potential duration was shorter in epicardial cells of gna11(-/-) mice than in wt (p < 0.05), while no difference was found in endocardial myocytes. These results suggest that Galpha(11)-coupled signalling is a central pathway in the regulation of I(to,f). It physiologically exerts a tonic inhibitory influence on the expression of I(to,f) and thereby contributes to the regulation of cardiac repolarisation.

UI MeSH Term Description Entries
D011188 Potassium An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000200 Action Potentials Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli. Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D015398 Signal Transduction The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway. Cell Signaling,Receptor-Mediated Signal Transduction,Signal Pathways,Receptor Mediated Signal Transduction,Signal Transduction Pathways,Signal Transduction Systems,Pathway, Signal,Pathway, Signal Transduction,Pathways, Signal,Pathways, Signal Transduction,Receptor-Mediated Signal Transductions,Signal Pathway,Signal Transduction Pathway,Signal Transduction System,Signal Transduction, Receptor-Mediated,Signal Transductions,Signal Transductions, Receptor-Mediated,System, Signal Transduction,Systems, Signal Transduction,Transduction, Signal,Transductions, Signal
D015640 Ion Channel Gating The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability. Gating, Ion Channel,Gatings, Ion Channel,Ion Channel Gatings
D043802 GTP-Binding Protein alpha Subunits, Gq-G11 A family of heterotrimeric GTP-binding protein alpha subunits that activate TYPE C PHOSPHOLIPASES dependent signaling pathways. The Gq-G11 part of the name is also spelled Gq/G11. G alpha q Protein,G-Protein, Gq,G-Protein, Gq alpha Family,G-Protein, Gq-G11 alpha Family,G alpha Protein q,G alpha11 Protein,G-Protein, G11,G-Protein, Gq-G11,GTP-Binding Protein alpha Subunit, G11,GTP-Binding Protein alpha Subunit, Gq,Galpha11 Protein,Galphaq Protein,Gq Protein,Gq-G11 G-Protein Family,Gq-G11 G-Proteins,Family, Gq-G11 G-Protein,G Protein, G11,G Protein, Gq,G Protein, Gq G11,G Protein, Gq G11 alpha Family,G Protein, Gq alpha Family,G-Protein Family, Gq-G11,G-Proteins, Gq-G11,G11 G-Protein,GTP Binding Protein alpha Subunit, G11,GTP Binding Protein alpha Subunit, Gq,GTP Binding Protein alpha Subunits, Gq G11,Gq G-Protein,Gq G11 G Protein Family,Gq G11 G Proteins,Gq-G11 G-Protein,Protein, G alpha11,Protein, Galpha11,alpha11 Protein, G
D051379 Mice The common name for the genus Mus. Mice, House,Mus,Mus musculus,Mice, Laboratory,Mouse,Mouse, House,Mouse, Laboratory,Mouse, Swiss,Mus domesticus,Mus musculus domesticus,Swiss Mice,House Mice,House Mouse,Laboratory Mice,Laboratory Mouse,Mice, Swiss,Swiss Mouse,domesticus, Mus musculus
D051605 Kv Channel-Interacting Proteins A family of neuronal calcium-sensor proteins that interact with and regulate potassium channels, type A. Potassium Channel Interacting Proteins,A-Type Potassium Channel Modulatory Protein 1,A-Type Potassium Channel Modulatory Protein 2,A-Type Potassium Channel Modulatory Protein 3,A-Type Potassium Channel Modulatory Protein 4,A-Type Potassium Channel Modulatory Proteins,Calsenilin,Calsenilin-Like Protein,Downstream Regulatory Element Antagonist Modulator,KChIP Proteins,KChIP1 Protein,KChIP2 Protein,KChIP3 Protein,KChIP4 Protein,Kv Channel-Interacting Protein 1,Kv Channel-Interacting Protein 2,Kv Channel-Interacting Protein 3,Kv Channel-Interacting Protein 4,Type A Potassium Channel Interacting Proteins,A Type Potassium Channel Modulatory Protein 1,A Type Potassium Channel Modulatory Protein 2,A Type Potassium Channel Modulatory Protein 3,A Type Potassium Channel Modulatory Protein 4,A Type Potassium Channel Modulatory Proteins,Calsenilin Like Protein,Kv Channel Interacting Protein 1,Kv Channel Interacting Protein 2,Kv Channel Interacting Protein 3,Kv Channel Interacting Protein 4,Kv Channel Interacting Proteins,Protein, KChIP4
D051672 Shal Potassium Channels A shaker subfamily of potassium channels that participate in transient outward potassium currents by activating at subthreshold MEMBRANE POTENTIALS, inactivating rapidly, and recovering from inactivation quickly. KCND1 Potassium Channel,KCND2 Potassium Channel,KCND3 Potassium Channel,Kv4 Potassium Channels,Kv4.1 Potassium Channel,Kv4.2 Potassium Channel,Kv4.3 Potassium Channel,Kv4.3L Potassium Channel,Potassium Channel, KCND1,Potassium Channel, KCND2,Potassium Channel, KCND3,Potassium Channel, Kv4.1,Potassium Channel, Kv4.2,Potassium Channel, Kv4.3,Potassium Channel, Kv4.3L,Potassium Channels, Kv4,Potassium Channels, Shal

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