ETHNOPHARMACOLOGICAL RELEVANCE: Pulmonary hypertension (PH) is a serious and progressive disease, posing a significant challenge to patient survival and quality of life. However, current treatments have limited effectiveness. Tianlong Kechuanling (TL) is a traditional Chinese medicine (TCM) compound formulation commonly used in clinical practice for the treatment of pulmonary heart disease, but its underlying mechanism is unknown. AIM OF THE STUDY: This study aimed to validate the mitigating effect of TL on PH and to further investigate its mechanism. MATERIALS AND METHODS: A rat model of PH was induced by SU5416 combined with hypoxia (SuHx). The effects of TL on PH were evaluated through right ventricular systolic pressure (RVSP), Right ventricular hypertrophy index (RVHI) and histopathological analysis. The serum levels of HIF-1α, VEGFA in rats were detected by ELISA
VEGFR2, Vimentin and CD31 were detected by immunohistochemistry to explore the mechanism of action of TL. Human pulmonary artery endothelial cells (HPAECs) were induced by hypoxia, and the effects of TL were confirmed by RT-PCR and Western Blotting. Liquid chromatography-mass spectrometry (LC-MS) analysis was used to identify the chemical composition of TL. RESULTS: TL ameliorated PH through modulation of the HIF-1α/VEGFA pathway and endothelial-to-mesenchymal transition (End-MT). The study also identified the key chemical components responsible for these effects. CONCLUSIONS: The study demonstrates that TL can improve PH by inhibiting End-MT, supporting the further development of TL as an effective therapeutic option for PH.