title: Transmural heterogeneity and remodeling of ventricular excitation-contraction coupling in human heart failure.
abstract: BACKGROUND
  Excitation-contraction (EC) coupling is altered in end-stage heart failure. However, spatial heterogeneity of this remodeling has not been established at the tissue level in failing human heart. The objective of this article was to study functional remodeling of excitation-contraction coupling and calcium handling in failing and nonfailing human hearts.
  
  
  RESULTS
  We simultaneously optically mapped action potentials and calcium transients in coronary perfused left ventricular wedge preparations from nonfailing (n=6) and failing (n=5) human hearts. Our major findings are the following. First, calcium transient duration minus action potential duration was longer at subendocardium in failing compared with nonfailing hearts during bradycardia (40 bpm). Second, the transmural gradient of calcium transient duration was significantly smaller in failing hearts compared with nonfailing hearts at fast pacing rates (100 bpm). Third, calcium transient in failing hearts had a flattened plateau at the midmyocardium and exhibited a 2-component slow rise at the subendocardium in 3 failing hearts. Fourth, calcium transient relaxation was slower at the subendocardium than at the subepicardium in both groups. Protein expression of sarcoplasmic reticulum Ca(2+)-ATPase 2a was lower at the subendocardium than the subepicardium in both nonfailing and failing hearts. Sarcoplasmic reticulum Ca(2+)-ATPase 2a protein expression at subendocardium was lower in hearts with ischemic cardiomyopathy compared with those with nonischemic cardiomyopathy.
  
  
  CONCLUSIONS
  For the first time, we present direct experimental evidence of transmural heterogeneity of excitation-contraction coupling and calcium handling in human hearts. End-stage heart failure is associated with the heterogeneous remodeling of excitation-contraction coupling and calcium handling.
authors.affiliation: Department of Biomedical Engineering, Washington University, St. Louis, MO, USA.
authors.forename: Qing
authors.initials: Q
authors.lastname: Lou
authors.forename: Vadim V
authors.initials: VV
authors.lastname: Fedorov
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Glukhov
authors.forename: Nader
authors.initials: N
authors.lastname: Moazami
authors.forename: Vladimir G
authors.initials: VG
authors.lastname: Fast
authors.forename: Igor R
authors.initials: IR
authors.lastname: Efimov
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000328:Adult; D000368:Aged; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000502:physiology; D002135:Calcium-Binding Proteins / Q000378:metabolism; D009202:Cardiomyopathies / Q000378:metabolism / Q000503:physiopathology; D005260:Female; D006333:Heart Failure / Q000378:metabolism / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology*; D017202:Myocardial Ischemia / Q000378:metabolism / Q000503:physiopathology; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism; D020257:Ventricular Remodeling / Q000502:physiology*; D000099211:Phospholamban
chemical_list: D002118:Calcium; D015220:Calcium Channels; D002135:Calcium-Binding Proteins; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000099211:Phospholamban