title: Angiotensin-(1-7) prevent atrial tachycardia induced sodium channel remodeling.
abstract: BACKGROUND
  Activation of the renin-angiotensin system plays an important role in atrial electrical remodeling; angiotensin-(1-7) (Ang-(1-7)) counterbalances the actions of angiotensin II. The aim of this study was to determine the effects of Ang-(1-7) on cardiac sodium current (INa ) in a canine model of atrial tachycardia.
  
  
  METHODS
  Eighteen dogs were randomly assigned to sham, pacing, or pacing + Ang-(1-7) groups (n = 6 in each group). Rapid atrial pacing (500 beats/min) was maintained for 2 weeks, while the dogs in the sham group were not paced. Ang-(1-7) (6 μg/kg/h) was administered intravenously during pacing. Whole-cell patch clamp techniques were utilized to record INa from canine atrial myocytes. Reverse transcription-polymerase chain reaction was used to assess possible underlying changes in cardiac Na(+) channels (Nav1.5).
  
  
  RESULTS
  Our results showed that INa density and expression of the Nav1.5 mRNA significantly decreased following pacing (P < 0.05 vs sham); however, the half-activation voltage (V1/2act ) and half-inactivation voltage (V1/2inact ) of INa were not significantly altered (P > 0.05 vs sham). Ang-(1-7) treatment significantly increased INa densities and hyperpolarized V1/2act without concomitant changes in V1/2inact but have no effect on the expression of the Nav1.5 gene.
  
  
  CONCLUSIONS
  Ang-(1-7) significantly increased INa densities, which contributed to improving intraatrial conduction and decreasing the likelihood of atrial fibrillation maintenance.
authors.affiliation: Department of Cardiology, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin, People's Republic of China.
authors.forename: Xuewen
authors.initials: X
authors.lastname: Wang
authors.forename: Guangping
authors.initials: G
authors.lastname: Li
mesh_terms: D000803:Angiotensin I / Q000627:therapeutic use*; D000818:Animals; D064752:Atrial Remodeling / Q000187:drug effects*; D004285:Dogs; D005260:Female; D015870:Gene Expression; D008297:Male; D062554:NAV1.5 Voltage-Gated Sodium Channel / Q000235:genetics / Q000502:physiology*; D010446:Peptide Fragments / Q000627:therapeutic use*; D013617:Tachycardia, Supraventricular / Q000235:genetics / Q000503:physiopathology*
chemical_list: D062554:NAV1.5 Voltage-Gated Sodium Channel; D010446:Peptide Fragments; D000803:Angiotensin I; C118790:angiotensin I (1-7)
keywords: angiotensin-(1-7); atrial electrical remodeling; renin-angiotensin system; sodium current