[Cardiac protective effect of the autoantibody against β3-adrenoceptor in rats with experimental heart failure].

Objective: To explore the effect of the autoantibody against the β3-adrenoceptor on rats with experimental heart failure.
Method: The peptide corresponding to the sequence of β3 adrenoceptor was synthesized to actively immunize the rats, ELISA was used to detect the serum level of autoantibody against the β3-adrenoceptor (β3AA). Total IgGs were extracted from the serum containing β3AA in immunized rats. Aortic banding surgery was used to establish the heart failure model in male Wistar rats and rats were divided into the sham group (n = 8), heart failure group(n = 8),β3AA-immunized heart failure group (HF+β3AA, n = 8) and corresponding negative IgG-immunized heart failure group (HF+ IgG, n = 8).In 6 weeks and 8 weeks after aortic banding surgery, the serum levels of NT-pro brain natriuretic peptide (NT-proBNP) were assayed with ELISA assay and cardiac function was assessed by echocardiography.
Results: β3AA was used to immunize rat with heart failure, the serum level of β3AA was stable at 50 days post immunization. At 8 weeks after aortic banding surgery, heart failure group showed significantly increased LVEDD [(6.92 ± 0.22) mm vs.(5.62 ± 0.19) mm, P < 0.001], LVESD [(4.63 ± 0.23) mm vs.(3.50 ± 0.20) mm, P < 0.01] and IVS [(2.44 ± 0.06) mm vs.(2.28 ± 0.05) mm, P < 0.05], and decreased LVEF[(62.07 ± 3.99)% vs.(79.63 ± 3.02)%, P < 0.01] and LVFS [(31.46 ± 3.22)% vs.(43.65 ± 2.68) %, P < 0.05] compared with the sham group.HF+β3AA IgG group showed decreased LVEDD [(6.07 ± 0.30) mm vs.(6.92 ± 0.24) mm, P < 0.05] and LVESD [(3.92 ± 0.22) mm vs.(4.68 ± 0.23) mm, P < 0.05], and higher LVEF [(70.29 ± 1.78)% vs.(61.95 ± 3.03)%, P < 0.05] and LVFS [(38.08 ± 2.32)% vs.(30.50 ± 1.82)%, P < 0.05] compared to the HF+ IgG group.In addition, compared with the HF+ IgG group, HF+β3AA IgG group showed decreased serum levels of NT-proBNP [(196.43 ± 6.56) pg/ml vs.(242.13 ± 7.86) pg/ml, P < 0.01].
Conclusion: Our results demonstrate that β3AA can improve cardiac function and reduce the serum levels of NT-proBNP in rat with heart failure.