title: E-4031 enhanced Ca2+ transient and ventricular myocytes contraction via reverse mode Na+/Ca2+ exchange in normal and hypertrophic rats.
abstract: OBJECTIVE
  To study the effects of N-[4-[[1-[2-(6-methyl-2-pyridinyl)ethyl]-4-piperidinyl]carbonyl]phenyl]methanesulfonamide dihydrochloride dihydrate (E-4031), a specific Ik blocker, on Ca2+ transient and cell contraction of normal and hypertrophied rat ventricular myocytes.
  
  
  METHODS
  Electrically triggered Ca2+ transient and cell shortening were measured simultaneously using the Ion Imaging System with charge coupled digital (CCD) camera.
  
  
  RESULTS
  E-4031 (10 micromol/L) increased Ca2+ transient and cell shortening from (210+/-49) and (3.0+/-0.8) micron to (245+/-47) and (3.6+/-1.0) micron, respectively (P<0.05) in normal cardiomyocytes and from (196+/-54) and (3.0+/-1.3) micron to (240+/-49) and (3.6+/-1.3) micron respectively (P<0.05) in hypertrophied cardiomyocytes, while did not change calcium sensitivity in both groups. KB-R7943 completely blocked the activating effects induced by E-4031 in both of normal and hypertrophied cardiomyocytes. Nicardipine did not block the increasing effects of E-4031.
  
  
  CONCLUSIONS
  E-4031 increased Ca2+ transient and cell contraction via stimulating reverse mode of Na+/Ca2+ exchange while without influencing calcium sensitivity. These effects were more notable in hypertrophied cardiomyocytes than in normal myocytes.
authors.affiliation: Department of Physiology, Shanxi Medical University, Taiyuan 030001, China. xianglic@sohu.com
authors.forename: Xiang-Li
authors.initials: XL
authors.lastname: Cui
authors.forename: Lu-Ying
authors.initials: LY
authors.lastname: Zhao
authors.forename: Bo-Wei
authors.initials: BW
authors.lastname: Wu
mesh_terms: D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D004558:Electric Stimulation; D017379:Hypertrophy, Left Ventricular / Q000378:metabolism*; D009200:Myocardial Contraction / Q000187:drug effects*; D010880:Piperidines / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D019831:Sodium-Calcium Exchanger / Q000378:metabolism*
chemical_list: D000889:Anti-Arrhythmia Agents; D010880:Piperidines; D011725:Pyridines; D019831:Sodium-Calcium Exchanger; C063968:E 4031; D002118:Calcium