title: Location and density of alpha- and beta-adrenoreceptor sub-types in myocardium after mechanical left ventricular unloading.
abstract: BACKGROUND
  We hypothesized that not all subtypes of alpha- and beta-adrenoreceptors undergo similar upregulation and redistribution in human myocardium after mechanical unloading with an assist device.
  
  
  METHODS
  We obtained core biopsy samples of the left ventricle in 19 patients before and after removal of a Jarvik or Thoratec left ventricular assist device (LVAD) to study the effect of mechanical unloading on the distribution of alpha- and beta-adrenoreceptors. Fresh, embedded tissue sections were incubated with receptor blockers and antibodies before the fluorescent labeling of receptors. Images were obtained by fluorescence deconvolution microscopy, and composite tissue renditions were made from the stacked images. Multiple adrenoreceptor subtypes were studied.
  
  
  RESULTS
  We saw a reversal of myocyte hypertrophy in all patients, but the upregulation of receptors was not seen in all post-LVAD tissue samples. Furthermore, we noted receptor relocalization from an initial punctate/clumped pattern to a normal homogeneous distribution in many patients. Significant differences were seen in the distribution of beta(2)- and alpha(1)-receptors and in alpha(1A) subtypes.
  
  
  CONCLUSIONS
  In this study we show not only the expected reversal of myocyte hypertrophy and the increase in adrenoreceptors after ventricular unloading, but also the relocalization of specific receptor subtypes.
authors.affiliation: Department of Cardiovascular Surgical Research, Texas Heart Institute, St Luke's Episcopal Hospital, Houston, Texas, USA.
authors.forename: Pippa M
authors.initials: PM
authors.lastname: Schnee
authors.forename: Naeema
authors.initials: N
authors.lastname: Shah
authors.forename: Marianne
authors.initials: M
authors.lastname: Bergheim
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Poindexter
authors.forename: L Maximilian
authors.initials: LM
authors.lastname: Buja
authors.forename: Courtney
authors.initials: C
authors.lastname: Gemmato
authors.forename: Branislav
authors.initials: B
authors.lastname: Radovancevic
authors.forename: George V
authors.initials: GV
authors.lastname: Letsou
authors.forename: O Howard
authors.initials: OH
authors.lastname: Frazier
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Bick
mesh_terms: D000328:Adult; D001707:Biopsy, Needle; D005260:Female; D006333:Heart Failure / Q000473:pathology* / Q000628:therapy*; D016027:Heart Transplantation; D006353:Heart-Assist Devices; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology*; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta
chemical_list: D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta