Interaction between AT1 and AT2 receptors during postinfarction left ventricular remodeling

Szilard Voros, Zequan Yang, Christina M. Bove, Wesley D. Gilson, Frederick H. Epstein, Brent A. French, Stuart S. Berr, Sanford P. Bishop, Mark R. Conaway, Hiroaki Matsubara, Robert M. Carey, Christopher M. Kramer

Research output: Contribution to journalArticlepeer-review

Abstract

The relative contribution of the angiotensin II type 1 and 2 receptors (AT1-R and AT2-R) in postmyocardial infarction (MI) remodeling remains incompletely understood. We studied five groups of C57Bl/6 mice after 1 h of left anterior descending artery occlusion-reperfusion: 1) wild type, untreated (n = 12); 2) wild type, treated with the AT1-R blocker losartan (10-20 mg·kg-1·day-1 in drinking water) from day 1 to day 28 post-MI (n = 10); 3) cardiac overexpression of the AT2-R [AT2-transgenic (TG); n = 14]; 4) AT 2-TG treated with losartan (n = 13); and 5) AT2-TG and null for the AT1a-R [AT2-TG/AT1 knockout (KO); n = 10]. Cardiac magnetic resonance imaging (CMR) measured ejection fraction and left ventricular end-diastolic and endsystolic volume (EDVI and ESVI) and mass indexed to weight on days 0, 1, 7, and 28 post-MI. Infarct size was measured on day 1 by late gadolinium-enhanced CMR. Regional myocyte hypertrophy and collagen content were measured on day 28 post-MI. Infarct size was similar among groups. Systolic blood pressure was lowest in AT2-TG/AT1KO. By day 28 post-MI, when corrected for baseline differences, EDVI and ESVI were higher and ejection fraction was lower in wild type than other groups. Ejection fraction was highest and EDVI and mass index were lowest in AT 2-TG/AT1KO at day 28. The AT2-TG/AT 1KO demonstrated less fibrosis in adjacent regions. Regional myocyte hypertrophy was similar in all groups. The AT1-R and AT2-R are intricately intertwined in post-MI remodeling. Pharmacological blockade of AT1-R is equivalent to AT2-R overexpression in attenuating post-MI remodeling. Genetic knockout of the AT1a-R is additive to AT2-R overexpression, due, at least in part, to blood pressure lowering.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume290
Issue number3
DOIs
StatePublished - Mar 2006
Externally publishedYes

Keywords

  • Angiotensin
  • Magnetic resonance imaging
  • Myocardial infarction
  • Receptors

ASJC Scopus subject areas

  • Physiology

Fingerprint Dive into the research topics of 'Interaction between AT1 and AT2 receptors during postinfarction left ventricular remodeling'. Together they form a unique fingerprint.

Cite this