title: Increased expression of isoform 1 of the sarcoplasmic reticulum Ca(2+)-release channel in failing human heart.
abstract: BACKGROUND
  The sarcoplasmic reticulum (SR) Ca(2+)-release channel plays a key role in the excitation-contraction coupling of cardiac myocytes. Because respective alterations have been reported in human heart failure, we investigated isoform expression of the SR Ca(2+)-release channel in human hearts from patients with terminal heart failure (dilated cardiomyopathy [DCM], n=8) and nonfailing organ donors (NF, n=8).
  
  
  RESULTS
  Expression of mRNA of SR Ca(2+)-release channel isoforms in isolated human cardiomyocytes and myocardial tissue was analyzed by reverse-transcription polymerase chain reaction. Protein expression was quantified in myocardial tissue with [(3)H]-ryanodine binding and with Western blots, expressed as densitometric units per microgram of protein (DU), and cellular localization was visualized with immunohistochemistry. We found mRNA expression of isoforms 1, 2, and 3 in cardiomyocytes and myocardial tissue both in NF and DCM. Total SR Ca(2+)-release channel protein expression in NF (B(max) 2.16+/-0.43 pmol/mg protein) and in DCM (B(max) 2.33+/-0.22 pmol/mg protein) myocardium was unchanged. Expression of isoform 1 of the SR Ca(2+)-release channel was significantly (P=0.0037) increased in DCM myocardium (NF 1.97+/-0.25 versus DCM 3.37+/-0.31 DU), whereas protein expression of isoform 2 (NF 14.62+/-0.87 versus DCM 13.52+/-0.43 DU) and isoform 3 (NF 1.39+/-0.13 versus DCM 1.35+/-0.19 DU) was unchanged. All 3 isoforms of the protein could be localized in human ventricular myocytes with fluorescence immunohistochemistry.
  
  
  CONCLUSIONS
  All 3 isoforms of the SR Ca(2+)-release channel were determined in human ventricular cardiomyocytes. Increased expression of isoform 1 of the SR Ca(2+)-release channel could contribute to impaired excitation-contraction coupling in human heart failure.
authors.affiliation: Laboratory of Muscle Research and Molecular Cardiology, Klinik III für Innere Medizin, University of Cologne, Cologne, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Münch
authors.forename: B
authors.initials: B
authors.lastname: Bölck
authors.forename: A
authors.initials: A
authors.lastname: Sugaru
authors.forename: K
authors.initials: K
authors.lastname: Brixius
authors.forename: W
authors.initials: W
authors.lastname: Bloch
authors.forename: R H
authors.initials: RH
authors.lastname: Schwinger
mesh_terms: D000328:Adult; D001667:Binding, Competitive; D015153:Blotting, Western; D002311:Cardiomyopathy, Dilated / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D002478:Cells, Cultured; D005260:Female; D005786:Gene Expression Regulation; D006352:Heart Ventricles / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012433:Ryanodine / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics* / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism*; D014316:Tritium
chemical_list: D020033:Protein Isoforms; D012333:RNA, Messenger; D019837:Ryanodine Receptor Calcium Release Channel; D014316:Tritium; D012433:Ryanodine