Abstract
Pulmonary arterial hypertension (PAH) is a progressive disease with a high mortality rate. Previous studies have revealed the important function of the β3 adrenergic receptor (β3-AR) in cardiovascular diseases, and the potential beneficial effects of numerous β3-AR agonists on pulmonary vasodilation. Conversely, a number of studies have proposed that the antagonism of β3-AR may prevent heart failure. The present study aimed to investigate the functional involvement of β3-AR and the effects of the β3-AR antagonist, SR59230A, in PAH and subsequent heart failure. A rat PAH model was established by the subcutaneous injection of monocrotaline (MCT), and the rats were randomly assigned to groups receiving four weeks of SR59230A treatment or the vehicle control. SR59230A treatment significantly improved right ventricular function in PAH in vivo compared with the vehicle control (P<0.001). Additionally, the expression level of β3-AR was significantly upregulated in the lung and heart tissues of PAH rats compared with the sham group (P<0.01), and SR59230A treatment inhibited this increase in the lung (P<0.05), but not the heart. Specifically, SR59230A suppressed the elevated expression of endothelial nitric oxide and alleviated inflammatory infiltration to the lung under PAH conditions. These results are, to the best of our knowledge, the first to reveal that SR59230A exerts beneficial effects on right ventricular performance in rats with MCT-induced PAH. Furthermore, blocking β3-AR with SR59230A may alleviate the structural changes and inflammatory infiltration to the lung as a result of reduced oxidative stress.