Angiotensin II receptor gene expression in hypertrophied left ventricles of rat hearts

Konrad Wolf, Roberto Della Bruna, Günther Bruckschlegel, Heribert Schunkert, Günter A.J. Riegger, Armin Kurtz

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20 Scopus citations

Abstract

Objective. To examine the expression of angiotensin II AT(1a), AT(1b) and AT2 receptor genes in the left ventricles of rats subjected to ventricular pressure overloading induced by aortic banding for 6 weeks and then 6 weeks medical treatment. Results. Aortic banding was related to an increase in relative weight of the left ventricle from 1.73 ± 0.06 (sham-operated) to 2.81 ± 0.25 g/kg, an increase in β-myosin:α-myosin messenger RNA (mRNA) ratio from 0.30 ± 0.02 to 1.94 ± 0.55 and an 18-fold increase in left ventricular atrial natriuretic peptide mRNA levels. In contrast, left ventricular pressure overload hypertrophy was not related to a significant change in the abundance of AT(1a) and AT(1b) mRNA, which were expressed in a relative ratio of 5:1. Similarly, the abundance of AT2 mRNA was not significantly changed in hypertrophied ventricles. In rats receiving the angiotensin II AT1 receptor antagonist losartan (40 mg/kg) for 6 weeks after banding, relative heart weights were β-myosin:α-myosin ratio was natriuretic peptide mRNA levels displayed a blunted increase (11-fold over sham-treated controls), documenting a significant amelioration of left ventricular hypertrophy by blockade of the AT1 receptor. Conclusion. Losartan treatment in parallel did not affect AT(1A), AT(1b) and AT2 receptor mRNA levels, which were not different from those in vehicle-treated or sham-treated controls. These findings confirm that left ventricular hypertrophy in the rat is associated with increased ventricular expression of β-myosin and of atrial natriuretic peptide and with reduced expression of α-myosin. Despite these significant changes in cardiac gene expression no alteration was observed in AT(1A), AT(1b) and AT2 receptor mRNA levels.

Original languageEnglish
Pages (from-to)349-354
Number of pages6
JournalJournal of Hypertension
Volume14
Issue number3
DOIs
StatePublished - 1996
Externally publishedYes

Keywords

  • Angiotensin II receptors
  • Atrial natriuretic peptide
  • Hypertrophy
  • Losartan
  • α-myosin/β-myosin

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