OBJECTIVETo investigate the effects of renal denervation (RDN) on left atrial fibrosis in rats with chronic heart failure.

METHODSSixty healthy male Sprague Dawley rats were randomly assigned to control group (n=10, intraperitoneal injection with 5 mg/kg normal saline daily for 3 consecutive weeks), sham group (n=25) and RDN group (n=25). Rats in sham and RDN group were intraperitoneally injected with 5 mg/kg isoproterenol daily for 3 consecutive weeks. RDN and sham RDN procedure was implemented at week 5. The renal arteries and veins were not isolated and the nerves were left intact in sham group. The experiment ended at week 10. Cardiac function, diastolic interventricular septal thickness (IVSD) and left atrial dimension (LAD) were evaluated by echocardiography at baseline, week 5 and 10. The rats of all three groups were sacrificed at week 10 and the left atrial tissue was used for following analysis: fibrosis was detected by Masson staining, plasma BNP was measured by ELISA kit, the protein expression of AngII, TGF-β1, MMP2 and collagen I was determined by Western blot.

RESULTS(1) Cardiac function: compared with control group, LVEF decreased (P<0.01), IVSD (P<0.01) and LAD (P<0.01) increased significantly in the sham and RDN group at week 5. Compared with sham group at week 10, LVEF and IVSD significantly improved (P<0.05) and LAD tended to be smaller (P>0.05) in RDN group. (2) The degree of left atrial tissue fibrosis: Masson staining (collagen volume fraction, CVF) showed significantly decreased fibrosis of left atrial tissue in RDN group compared with that in sham group (P<0.01). (3) Plasma BNP level: ELISA assay revealed that plasma BNP in sham group was significantly increased compared with that in control group (P<0.05) and was similar between RND group and control group at week 10. (4) Protein expression of AngII, TGF-β1, MMP2 and collagen I in rats left atrial: Western blot analysis demonstrated that the expression of AngII, TGF-β1, MMP2 and collagen I was significantly down-regulated in RDN group compared to sham group (all P<0.05) but still significantly higher than in control group (all P<0.05).

CONCLUSIONSRDN can effectively attenuate the left atrial fibrosis in rats with isoproterenol induced chronic heart failure. The attenuation of left atrial fibrosis by RDN in these rats may be attributed to improved cardiac function and downregulated pro-fibrogenic factors (AngII, TGF-β1, MMP2 and collagen I).