title: Functional analysis of a novel antagonistic antibody against the short epitope of the α1A-adrenergic receptor.
abstract: OBJECTIVE
  The alpha1A-adrenergic receptor (α1A-AR) regulates various vascular functions and participates in the pathogenesis of primary hypertension. However, highly specific and subtype-selective antagonists of α1A-AR have not been developed.
  
  
  RESULTS
  Two novel antibodies against the short peptides CP-7, which is located in the second extracellular loop of α1A-AR, and CPE-8, which is located in the third extracellular loop of α1A-AR, were prepared. The two antibodies specifically bound to α1A-AR. However, neither antibody prevented [(3)H]-epinephrine or [(3)H]-prazosin from binding to the receptor. In vitro, the anti-CP-7 antibody inhibited Ca(2+)-dependent signal transduction processes including protein kinase C translocation and extracellular signal-regulated kinase (ERK1/2) phosphorylation induced by phenylephrine (PHE). The anti-CP-7 antibody decreased the beating rates of neonatal rat cardiomyocytes with or without PHE stimulation and reduced the blood pressure of spontaneously hypertensive rats that were immunized with CP-7-keyhole limpet haemocyanin.
  
  
  CONCLUSIONS
  The anti-CP-7 antibody specifically inhibited the activation of α1A-AR both in vitro and in vivo. No competition binding was found between anti-CP-7 and [(3)H]-epinephrine or [(3)H]-prazosin. An antibody that specifically inhibits a receptor could be useful in research on G-protein-coupled receptors that lack specific antagonists. The antibody against the epitope CP-7 might have potential in a therapeutic application for treating primary hypertension.
authors: Laboratory of Cardiovascular Immunology, Key Laboratory of Molecular Targeted Therapies of the Ministry of Education,  Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jie-Fang Avenue, Wuhan 430022,  China.
authors: Fen
authors: F
authors: Chen
authors: Xiao
authors: X
authors: Chen
authors: Zhihua
authors: Z
authors: Qiu
authors: Min
authors: M
authors: Wang
authors: Shijun
authors: S
authors: Yang
authors: Mustafa
authors: M
authors: Khamis
authors: Miao
authors: M
authors: Yu
authors: Xian
authors: X
authors: Yu
authors: Zuxia
authors: Z
authors: Liu
authors: Lan
authors: L
authors: Wang
authors: Zihua
authors: Z
authors: Zhou
authors: Yuhua
authors: Y
authors: Liao
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D000906:Antibodies / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004837:Epinephrine / Q000378:metabolism; D000939:Epitopes / Q000276:immunology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D007114:Immunization; D009131:Muscle, Smooth, Vascular / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism; D010656:Phenylephrine / Q000494:pharmacology; D010766:Phosphorylation; D011224:Prazosin / Q000378:metabolism; D051571:Protein Kinase C-alpha / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D018340:Receptors, Adrenergic, alpha-1 / Q000276:immunology*
chemical_list: D000317:Adrenergic alpha-Antagonists; D000906:Antibodies; D000939:Epitopes; D018340:Receptors, Adrenergic, alpha-1; D010656:Phenylephrine; D051571:Protein Kinase C-alpha; D048049:Extracellular Signal-Regulated MAP Kinases; D002118:Calcium; D011224:Prazosin; D004837:Epinephrine