BACKGROUND: The role of angiotensin II type 1 (AT1) and type 2 (AT2) receptors in cardiac hypertrophy and fibrosis is incompletely understood. The availability of AT2 receptor-deficient mice (AT2 -/y) makes it possible to study the effects of AT1 receptors without the confounding influence of AT2 receptor activity. OBJECTIVE: To test the hypothesis that the AT2 receptor affords protection from left ventricular hypertrophy and fibrosis in chronic hypertension induced by N-nitro-L-arginine methyl ester (L-NAME). DESIGN: Four groups of mice were studied over a period of 3 weeks: AT2 -/y mice with and without L-NAME, and AT2 +/y mice with and without L-NAME. METHODS: Blood pressure and heart rate were monitored by telemetry in groups of AT2 +/y and AT2 -/y mice for 4 weeks. L-NAME groups received the compound in drinking water for the last 3 weeks. We determined left ventricular AT1 receptor expression, cardiac hypertrophy and fibrosis, with and without L-NAME treatment. We used a miniaturized conductance-manometer system to measure pressure-volume loops at the time when the animals were killed. RESULTS: AT2 -/y mice treated with L-NAME showed worse left ventricular hypertrophy, more perivascular fibrosis and greater concentrations of brain natriuretic peptide than did AT2 +/y mice treated with L-NAME. The end-systolic pressure-volume relationship, an index of left ventricular contractility, was decreased in AT2 -/y mice treated with L-NAME. CONCLUSIONS: The AT2 receptor is not essential for development of L-NAME-induced cardiac hypertrophy, fibrosis and concomitant changes in left ventricular performance. In contrast, the AT2 receptor offers a protective effect.
BACKGROUND: The role of angiotensin II type 1 (AT1) and type 2 (AT2) receptors in cardiac hypertrophy and fibrosis is incompletely understood. The availability of AT2 receptor-deficient mice (AT2 -/y) makes it possible to study the effects of AT1 receptors without the confounding influence of AT2 receptor activity. OBJECTIVE: To test the hypothesis that the AT2 receptor affords protection from left ventricular hypertrophy and fibrosis in chronic hypertension induced by N-nitro-L-arginine methyl ester (L-NAME). DESIGN: Four groups of mice were studied over a period of 3 weeks: AT2 -/y mice with and without L-NAME, and AT2 +/y mice with and without L-NAME. METHODS: Blood pressure and heart rate were monitored by telemetry in groups of AT2 +/y and AT2 -/y mice for 4 weeks. L-NAME groups received the compound in drinking water for the last 3 weeks. We determined left ventricular AT1 receptor expression, cardiac hypertrophy and fibrosis, with and without L-NAME treatment. We used a miniaturized conductance-manometer system to measure pressure-volume loops at the time when the animals were killed. RESULTS:AT2 -/y mice treated with L-NAME showed worse left ventricular hypertrophy, more perivascular fibrosis and greater concentrations of brain natriuretic peptide than did AT2 +/y mice treated with L-NAME. The end-systolic pressure-volume relationship, an index of left ventricular contractility, was decreased in AT2 -/y mice treated with L-NAME. CONCLUSIONS: The AT2 receptor is not essential for development of L-NAME-induced cardiac hypertrophy, fibrosis and concomitant changes in left ventricular performance. In contrast, the AT2 receptor offers a protective effect.
Authors: U Muscha Steckelings; Robert E Widdop; Edward D Sturrock; Lizelle Lubbe; Tahir Hussain; Elena Kaschina; Thomas Unger; Anders Hallberg; Robert M Carey; Colin Sumners Journal: Pharmacol Rev Date: 2022-10 Impact factor: 18.923
Authors: Emma S Jones; Antony Vinh; Claudia A McCarthy; Tracey A Gaspari; Robert E Widdop Journal: Pharmacol Ther Date: 2008-08-31 Impact factor: 12.310