Early responses of the left ventricle to pressure overload in Wistar rats

Authors: Roussel, ÉliseGaudreau, MartinPlante, ÉricDrolet, Marie-ClaudeBreault, CatherineCouët, JacquesArsenault, Marie
Other Title(s): Early LV signaling events in pressure overload
Abstract: The early events leading to the establishment of left ventricular hypertrophy associated to pressure overload (PO) are not well characterized. To explore these early events, aortic banding (AB) was performed in rats to induce left ventricle (LV) PO. Animals were sacrificed after 24, 48 h or 14 days. An echocardiogram was performed before the procedure and at sacrifice. LVs were preserved for the evaluation of fibrosis, angiotensin II (AT) receptors expression and stress-related MAP kinases (ERK 1/2, JNK and p38) pathways. We observed that concentric LV hypertrophy was established after only 14 days. Collagen I and fibronectin gene expressions were decreased the first 2 days after AB induction whereas AT receptors mRNA levels were sharply increased. ERK 1/2 and JNK activities in LV homogenates were decreased 24 h after AB but came back to normal after 14 days. p38 activity however was stable during the period studied. We also evaluated the presence of two phosphorylated transcription factors related to JNK signaling pathway (ATF-2 and c-Jun) in cardiomyocyte nuclei. The proportion of LV cell nuclei positive for these two activated transcription factors was significantly reduced in AB rats compared to sham. These results suggest that the early response of the LV to acute PO is to attenuate the expression of some pro-fibrotic and pro-hypertrophic signaling pathways and possibly AT signaling by decreasing ERK 1/2 and JNK relative activities.
Document Type: Article de recherche
Issue Date: 29 November 2007
Open Access Date: 14 November 2017
Document version: AM
Permalink: http://hdl.handle.net/20.500.11794/15843
This document was published in: Life sciences, Vol. 82 (5-6), 265-272 (2008)
Alternative version: 10.1016/j.lfs.2007.11.008
Collection:Articles publiés dans des revues avec comité de lecture

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