title: Alterations of subtypes of cardiac adrenoceptors in old rat.
abstract: OBJECTIVE
  To determine alterations of subtypes of myocardial adrenoceptors in senescence.
  
  
  METHODS
  Heart membrane preparations were made from 3- and 25-month old Wistar rats. Alpha 1- and beta-adrenoceptors were measured by radioligand, 125I-BE2254 and 125I-pindolol, binding assays, respectively.
  
  
  RESULTS
  In the old rat heart, alpha 1- and beta-adrenoceptor densities were declined from the young rats of 119 +/- 4 and 45.9 +/- 1.9 pmol L-1 to 70 +/- 6 and 36.4 +/- 1.6 pmol L-1 (P < 0.01), with a greater change in alpha 1-AR and in beta-AR. The ratio of alpha 1A/alpha 1B subtypes was decreased from the young rats of 39/61 to the old rats of 26/74 (P < 0.05).
  
  
  CONCLUSIONS
  The cardiac adrenoceptors are decreased with different extents in the different subtypes in old rats.
authors.affiliation: Institute of Vascular Medicine, Beijing Medical University, China.
authors.forename: G S
authors.initials: GS
authors.lastname: Yu
authors.forename: M Z
authors.initials: MZ
authors.lastname: Chen
authors.forename: Q D
authors.initials: QD
authors.lastname: Han
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D009206:Myocardium / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D017208:Rats, Wistar; D018340:Receptors, Adrenergic, alpha-1 / Q000145:classification / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*
chemical_list: D018340:Receptors, Adrenergic, alpha-1; D011943:Receptors, Adrenergic, beta