Simultaneous activation of p38 MAPK and p42/44 MAPK by ATP stimulates the K+ current ITREK in cardiomyocytes.
Living cells exhibit multiple K(+) channel proteins; among these is the recently reported atypical two-pore domain K(+) channel protein TREK-1. Most K(+) currents are modulated by neurohormones and under various pathological conditions. Here, in rat ventricular cardiomyocytes using the whole-cell patch-clamp technique, we characterize for the first time a native TREK-1-like current (I(TREK)) that is activated by ATP, a purine agonist applied at a micromolar range. This current is sensitive to arachidonic acid, intracellular acidosis, and various K(+) current inhibitors. Reverse transcription-polymerase chain reaction reveals the presence of a TREK-1-like mRNA in rat cardiomyocytes that shows 93% identity with mouse TREK-1. ATP effects are greatly attenuated in the presence of arachidonic acid or HCO(-)(3)-induced intracellular acidosis. Using a series of inhibitors, we further demonstrate that the ATP-induced stimulation of I(TREK) implies the activation of cytosolic phospholipase A(2) and the release of arachidonic acid. These events require the simultaneous involvement of p38 MAPK and p42/44 MAPK, respectively, via a cAMP-dependent protein kinase and a tyrosine kinase pathway, whereas the two MAPKs conjugate to activate a mitogen- and stress-activated protein kinase (MSK-1). Our results thus demonstrate the occurrence of a TREK-1-like current in cardiac cells whose activation by purine agonists implies a dual-MAPK cytosolic pathway.
Aimond
F
F
INSERM U-390, Physiopathologie cardiovasculaire, IFR N degrees 3, CHU Arnaud de Villeneuve, F-34295 Montpellier Cedex 5, France.
Rauzier
J M
JM
Bony
C
C
Vassort
G
G
D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology; D015153:Blotting, Western; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology; D004622:Embryo, Mammalian / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006352:Heart Ventricles / Q000378:metabolism; D007477:Ions; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008954:Models, Biological; D009206:Myocardium / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism*; D024683:Potassium Channels, Tandem Pore Domain; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D038744:Ribosomal Protein S6 Kinases, 90-kDa; D048051:p38 Mitogen-Activated Protein Kinases
D004791:Enzyme Inhibitors; D007477:Ions; D015221:Potassium Channels; D024683:Potassium Channels, Tandem Pore Domain; D012333:RNA, Messenger; C103742:potassium channel protein TREK-1; D016718:Arachidonic Acid; D000242:Cyclic AMP; D011505:Protein-Tyrosine Kinases; D038744:Ribosomal Protein S6 Kinases, 90-kDa; C116919:mitogen and stress-activated protein kinase 1; D017868:Cyclic AMP-Dependent Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D010741:Phospholipases A; D011188:Potassium