In numerous cardiac diseases leading to heart failure, involvement of anti-β-adrenoceptors autoantibodies (β-aAb) has been demonstrated. However, to date no link has been made between degenerative mitral valve disease (DMVD) and those β-aAb. In order to evaluate their possible involvement in the disease development, King Charles spaniel dog was chosen as a study model, owing to its particular predisposition for this affection. Thus, aims of this study were to detect β1 – and β3-aAb presence in the sera of diseased dogs and to assess their impact on cardiovascular response to different β-adrenoceptors agonists in rats by acute passive immunization.

Blood samples were collected from 15 dogs, including 6 females and 9 males. Total immunoglobulins G (IgG) were purified and an ELISA assay was performed. Male SD rats were then passively immunized with the IgG (25μg IgG/kg/day for 3 days) of diseased dogs. A concentration-response curve to isoproterenol (10-10 to 10-6 M), a non-selective β-adrenergic agonist, was carried on isolated perfused rat hearts and dose-response curves to dobutamine (5 to 20μg/kg/min), a selective β1-adrenergic agonist, and SR58611A (5 to 40μg/kg/min), a preferential β3-adrenergic agonist, were performed on anaesthetized catheterized rats.

β1 – and β3-aAb were detected in all dogs sera. A strong trend to lower baseline values was observed for all parameters in isolated hearts of immunized rats, without any modification of the concentration-response curve to isoproterenol. In contrast, baseline values as well as dobutamine response remained unchanged for all parameters in anaesthetized immunized animals. However, response to SR58611A was attenuated in immunized rats, especially for arterial pressure parameters.

These preliminary results highlight the presence of β1 – and β3-aAb in the sera of dogs suffering from DMVD and suggest that β-aAb can exert functional effects within this pathological context.

The author hereby declares no conflict of interest