title: [Role of calcineurin in down-regulation of left ventricular transmural voltage- dependent K(+) currents in mice with heart failure].
abstract: The aim of the present study was to investigate the role of calcineurin in the down-regulation of left ventricular transmural voltage-dependent K(+) currents in heart failure. Transverse aorta was banded by using microsurgical techniques to create mouse heart failure model. Sham-operated (Sham) or aorta banded (Band) mice were randomized to receive calcineurin inhibitor cyclosporine A (CsA) or vehicle. The densities and kinetic properties of voltage-dependent K(+) currents, as well as action potential (AP), of left ventricular subendocardial (Endo) and subepicardial (Epi) myocytes were determined by using whole-cell patch-clamp technique. The results showed that calcineurin activity was significant higher in Endo myocytes than that in Epi ones in all the groups. Compared with Sham group, Band mice showed significantly increased calcineurin activity both in Endo and Epi myocytes. CsA significantly reduced calcineurin activity in Band mice. CsA treatment in Band mice partially reversed the down-regulation of Ito density, completely reversed the down-regulation of IK,slow density both in Endo and Epi myocytes, and Iss density in Endo myocytes. In addition, CsA treatment in Band mice partially antagonized the prolongation of action potential duration (APD), and APD at 50% (APD50) and 90% repolarization (APD90) were significantly reduced. Because of non-parallel shortening of APD in Endo and Epi myocytes, the ratio of Endo/Epi APD90 was reduced from 4.8:1 in Band mice to 2.6:1 in CsA-treated mice, which was close to that in Sham mice. The results suggest that non-parallel activation of calcineurin in Endo and Epi myocytes contributes to the down-regulation of transmural voltage-dependent K(+) currents and the amplification of transmural dispersion of repolarization (TDR) in left ventricular failure hearts. Inhibition of calcineurin may be a potential new therapeutic strategy to prevent and cure arrhythmias and sudden death in heart failure.
authors: Department of Pharmacology of Hebei Medical University, Key Laboratory of New Drug Pharmacology and Toxicology of Hebei Province, Key Laboratory of Neural and Vascular Biology of Ministry of Education, Shijiazhuang 050017, China.
authors: Chen-Xia
authors: CX
authors: Shi
authors: Department of Pharmacology of Hebei Medical University, Key Laboratory of New Drug Pharmacology and Toxicology of Hebei Province, Key Laboratory of Neural and Vascular Biology of Ministry of Education, Shijiazhuang 050017, China.
authors: Fang
authors: F
authors: Dong
authors: Department of Pharmacology of Hebei Medical University, Key Laboratory of New Drug Pharmacology and Toxicology of Hebei Province, Key Laboratory of Neural and Vascular Biology of Ministry of Education, Shijiazhuang 050017, China.
authors: Yan-Chao
authors: YC
authors: Chang
authors: Department of Orthopaedics, Third Hospital of Hebei Medical University, Shijiazhuang 050051, China.
authors: Xiao-Feng
authors: XF
authors: Wang
authors: Department of Pharmacology of Hebei Medical University, Key Laboratory of New Drug Pharmacology and Toxicology of Hebei Province, Key Laboratory of Neural and Vascular Biology of Ministry of Education, Shijiazhuang 050017, China. yanfangxu@hotmail.com.
authors: Yan-Fang
authors: YF
authors: Xu
mesh_terms: D000200:Action Potentials; D000818:Animals; D019703:Calcineurin / Q000502:physiology*; D065095:Calcineurin Inhibitors / Q000494:pharmacology; D016572:Cyclosporine / Q000494:pharmacology; D004195:Disease Models, Animal; D015536:Down-Regulation; D006321:Heart / Q000503:physiopathology; D006333:Heart Failure / Q000503:physiopathology*; D051379:Mice; D018408:Patch-Clamp Techniques; D024642:Potassium Channels, Voltage-Gated / Q000502:physiology*; D016277:Ventricular Function, Left
chemical_list: D065095:Calcineurin Inhibitors; D024642:Potassium Channels, Voltage-Gated; D016572:Cyclosporine; D019703:Calcineurin