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Br J Pharmacol. 2008 Feb;153(4):684-92. doi: 10.1038/sj.bjp.0707622. Epub 2008 Jan 14.

Knockout of beta(1)- and beta(2)-adrenoceptors attenuates pressure overload-induced cardiac hypertrophy and fibrosis.

Author information

1
Department of Experimental Cardiology, Baker Heart Research Institute, Melbourne, Victoria, Australia.

Abstract

BACKGROUND AND PURPOSE:

The role of beta-adrenoceptors in heart disease remains controversial. Although beta-blockers ameliorate the progression of heart disease, the mechanism remains undefined. We investigated the effect of beta-adrenoceptors on cardiac hypertrophic growth using beta(1)- and beta(2)-adrenoreceptor knockout and wild-type (WT) mice.

EXPERIMENTAL APPROACH:

Mice were subjected to aortic banding or sham surgery, and their cardiac function was determined by echocardiography and micromanometry.

KEY RESULTS:

At 4 and 12 weeks after aortic banding, the left ventricle:body mass ratio was increased by 80-87% in wild-type mice, but only by 15% in knockouts, relative to sham-operated groups. Despite the blunted hypertrophic growth, ventricular function in knockouts was maintained. WT mice responded to pressure overload with up-regulation of gene expression of inflammatory cytokines and fibrogenic growth factors, and with severe cardiac fibrosis. All these effects were absent in the knockout animals.

CONCLUSION AND IMPLICATIONS:

Our findings of a markedly attenuated cardiac hypertrophy and fibrosis following pressure overload in this knockout model emphasize that beta-adrenoceptor signalling plays a central role in cardiac hypertrophy and maladaptation following pressure overload.

PMID:
18193078
PMCID:
PMC2259198
DOI:
10.1038/sj.bjp.0707622
[Indexed for MEDLINE]
Free PMC Article

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