[Pulmonary hypertension: from molecular pathophysiology to haemodynamic abnormalities]

Protective effects of astragaloside IV against hypoxic pulmonary hypertension

The present study aimed to evaluate the protective effects of astragaloside IV (As-IV) against hypoxic pulmonary hypertension (HPH) and its mechanisms of action. Sprague-Dawley rats were used in a model of HPH induced by chronic hypoxia. After hypoxia, the mean pulmonary arterial pressure (mPAP), right ventricular pressure (RVP), and right ventricular hypertrophy index (RVHI) were monitored. Relaxation of the pulmonary artery in response to As-IV was measured. The levels of endothelin-1 (ET-1), angiotensin II (Ang II), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in serum were assessed. Cell proliferation was detected by the cell counting kit-8 (CCK-8) assay. Treatment with As-IV significantly decreased mPAP, RVP and RV/(LV + S) and attenuated the development of HPH. Moreover, As-IV time-dependently relaxed the pulmonary arteries from HPH rats. In addition, As-IV decreased the levels of ET-1, Ang II, TNF-α, and IL-6 in serum of HPH rats. In vitro experiments demonstrated that As-IV also significantly inhibited the proliferation of pulmonary artery smooth muscle cells (PASMCs) subjected to hypoxia. Our findings suggested the therapeutic potential of As-IV in the treatment of pulmonary hypertension.

Effects of baicalin on collagen Ι and collagen ΙΙΙ expression in pulmonary arteries of rats with hypoxic pulmonary hypertension

The synthesis and accumulation of collagen play an important role in the formation and progression of hypoxic pulmonary hypertension. Baicalin has been reported to prevent bleomycin-induced pulmonary fibrosis. However, the role of baicalin in the treatment of pulmonary hypertension remains unknown. A disintegrin and metalloprotease with thrombospondin type-1 motif (ADAMTS-1) is a secreted enzyme that acts on a wide variety of extracellular matrix (ECM) substrates associated with vascular diseases. In this study, we aimed to investigate the effects of baicalin on the synthesis of collagen I in rats with pulmonary hypertension induced by hypoxia and the changes in ADAMTS-1 expression. A total of 24 Sprague Dawley rats were randomly assigned to 3 groups as follows: the control group (C), the hypoxia group (H) and the hypoxia + baicalin group (B). The rats in groups H and B were kept in a normobaric hypoxic chamber for 4 weeks, and the rats in group C were exposed to room air. We measured the hemodynamic indexes, including mean pulmonary artery pressure (mPAP), mean systemic (carotid) artery pressure (mSAP), and then calculated the mass ratio of right ventricle to left ventricle plus septum [RV/(LV + S)] to reflect the extent of right ventricular hypertrophy. We measured the mRNA and protein expression levels of type I collagen, type III collagen and ADAMTS-1 by hybridization in situ, and immunohistochemistry and western blot analysis, respectively. The results revealed that treatment with baicalin significantly reduced pulmonary artery pressure and attenuated the remodeling of the pulmonary artery under hypoxic conditions by increasing the expression of ADAMTS-1, so that the synthesis of type I collagen and its mRNA expression were inhibited. In conclusion, baicalin effectively inhibits the synthesis of collagen I in pulmonary arteries and this is associated with an increase in the expression of ADAMTS-1. Thus, treatment with baicalin may be an effective method for lowering pulmonary artery pressure and preventing pulmonary artery remodeling.