title: Unchanged G-protein-coupled receptor kinase activity in the aging human heart.
abstract: OBJECTIVE
  We sought to find out whether G-protein-coupled receptor kinase (GRK) activity is also increased in the aging human heart.
  
  
  BACKGROUND
  In the aging and failing human heart, cardiac beta-adrenoceptors (beta-AR) are desensitized. In heart failure (HF), an increase in cardiac GRK activity considerably contributes to this beta-AR desensitization.
  
  
  METHODS
  We assessed GRK activity (by in vitro rhodopsin phosphorylation) in the right atria (RA) from 16 children (mean age 9 +/- 2 years) and 17 elderly patients (mean age 67 +/- 2 years) without apparent HF and in the RA from four patients with end-stage HF.Cytosolic and membranous GRK activities in the RA from children were not significantly different from those in elderly patients; in contrast, cytosolic and membranous GRK activities in the RA from patients with end-stage HF were significantly increased.
  
  
  CONCLUSIONS
  In contrast to the failing human heart, in the aging human heart, GRK activity is not increased. Thus, GRK activity appears to not play an important role in beta-AR desensitization in the aging human heart.
authors.affiliation: Departments of Pathophysiology and Nephrology, University of Essen School of Medicine, Essen, Germany
authors.forename: Kirsten
authors.initials: K
authors.lastname: Leineweber
authors.forename: Stefan
authors.initials: S
authors.lastname: Klapproth
authors.forename: Anja
authors.initials: A
authors.lastname: Beilfuss
authors.forename: Rolf-Edgar
authors.initials: RE
authors.lastname: Silber
authors.forename: Gerd
authors.initials: G
authors.lastname: Heusch
authors.forename: Thomas
authors.initials: T
authors.lastname: Philipp
authors.forename: Otto Erich
authors.initials: OE
authors.lastname: Brodde
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D020517:Atrial Appendage / Q000201:enzymology*; D002648:Child; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism* / Q000502:physiology; D005260:Female; D006333:Heart Failure / Q000201:enzymology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000201:enzymology*; D051552:beta-Adrenergic Receptor Kinases
chemical_list: D017868:Cyclic AMP-Dependent Protein Kinases; D051552:beta-Adrenergic Receptor Kinases; D000262:Adenylyl Cyclases