title: Different regulation of ERK1/2 activation by beta-adrenergic receptor subtypes in adult mouse cardiomyocytes.
abstract: BACKGROUND
  Increasing evidence suggests that stimulation of beta-adrenergic receptor (betaAR) activates mitogen-activated protein kinases (MAPKs), particularly extracellular signal-regulated kinase (ERK1/2) which is involved in the regulation of a multitude of cellular processes. However, the subtype-specific effects of betaAR stimulation on MAPKs remain to be elucidated.
  
  
  OBJECTIVE
  In the present study, we determined whether beta(1)AR and beta(2)AR differ in regulating ERK1/2 activation in the myocardium.
  
  
  METHODS
  To avoid complicated interactions between betaAR subtypes, we separately expressed either beta(1)AR or beta(2)AR using adenoviral gene transfer in adult mouse cardiac myocytes from beta(1)beta(2) double knockout mice.
  
  
  RESULTS
  Stimulation of beta(1)AR by isoproterenol markedly increased ERK phosphorylation and activity by 2.1-fold in a time-dependent manner. In contrast, stimulation of beta(2)AR slightly decreased ERK activation. Furthermore, pretreatment of cells with pertussis toxin to disrupt Gi function did not affect the inhibitory effect of beta(2)AR on ERK1/2.
  
  
  CONCLUSIONS
  We have shown that stimulation of cardiac betaAR subtypes differentially regulates ERK activation in adult mouse cardiomyocytes.
authors.affiliation: Institute of Cardiovascular Sciences, Peking University, Beijing 100083, PR China. zhengm@bjmu.edu.cn
authors.forename: Ming
authors.initials: M
authors.lastname: Zheng
authors.forename: Rong
authors.initials: R
authors.lastname: Hou
authors.forename: Qide
authors.initials: Q
authors.lastname: Han
authors.forename: Rui-Ping
authors.initials: RP
authors.lastname: Xiao