title: Chronic administration of KB-R7943 induces up-regulation of cardiac NCX1.
abstract: The NCX1 (sodium-calcium exchanger) is up-regulated in human heart failure and in many animal models of heart failure. The potential benefits and risks of therapeutically blocking NCX1 in heart failure and during ischemia-reperfusion are being actively investigated. In this study, we demonstrate that prolonged administration of the NCX1 inhibitor KB-R7943 resulted in the up-regulation of Ncx1 gene expression in both isolated adult cardiomyocytes and intact mouse hearts. Ncx1 up-regulation is mediated by the activation of p38. Importantly, p38 is not activated by KB-R7943 treatment in heart tubes from Ncx1(-/-) mice at 9.5 days postcoitum but is activated in heart tubes from Ncx1(+/+) mice. p38 activation does not appear to be in response to changes in cytosolic calcium concentration, [Ca(2+)](i). Interestingly, chronic KB-R7943 treatment in mice leads to the formation of an NCX1-p38 complex. Our study demonstrates for the first time that the electrogenic sarcolemma membrane cardiac NCX1 can act as a regulator of "activity-dependent signal transduction" leading to changes in gene expression.
authors: Department of Medicine, Gazes Cardiac Research Institute, Division of Cardiology, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
authors: Lin
authors: L
authors: Xu
authors: Christiana S
authors: CS
authors: Kappler
authors: Santhosh K
authors: SK
authors: Mani
authors: Neal R
authors: NR
authors: Shepherd
authors: Ludivine
authors: L
authors: Renaud
authors: Paige
authors: P
authors: Snider
authors: Simon J
authors: SJ
authors: Conway
authors: Donald R
authors: DR
authors: Menick
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000378:metabolism; D002415:Cats; D004789:Enzyme Activation / Q000187:drug effects; D006321:Heart / Q000187:drug effects*; D051379:Mice; D009206:Myocardium / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000235:genetics* / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors; D013890:Thiourea / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D013997:Time Factors; D015854:Up-Regulation / Q000187:drug effects*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: C101670:2-(2-(4-(4-nitrobenzyloxy)phenyl)ethyl)isothiourea methanesulfonate; D000319:Adrenergic beta-Antagonists; D000889:Anti-Arrhythmia Agents; D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D011943:Receptors, Adrenergic, beta; D019831:Sodium-Calcium Exchanger; D017923:Sodium-Hydrogen Exchangers; C110374:sodium-calcium exchanger 1; D048051:p38 Mitogen-Activated Protein Kinases; D013890:Thiourea