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Pulmonary arterial hypertension (PAH) is a progressive disease characterised by vascular remodelling. Inflammatory responses and oxidative stress have been shown to contribute to its progression. This study investigated the effects of a novel HIF-1α-miR-663b axis on pulmonary arterial smooth muscle inflammation, oxidative stress and apoptosis in a monocrotaline (MCT)-induced PAH rat model. A PAH rat model was constructed via MCT injection; moreover, miR-663b inhibitors were administered to inhibit miR-663b. PASMCs were cultured under hypoxic conditions to establish an in vitro PAH model. The data revealed that miR-663b was highly expressed in PAH rats and hypoxia-induced PASMC models. Overexpression of miR-663b exacerbated hypoxia-induced proliferation, apoptosis, migration and inflammation in PASMCs. Conversely, miR-663b inhibition reversed hypoxia-induced dysfunction in PASMCs. ZBP1 downregulation dampened miR-663b upregulation-mediated dysfunctions in PASMCs. In vivo experiments revealed that miR-663b inhibitors mitigated pulmonary arterial remodelling, inflammation and PANoptosis in MCT-induced PAH rats. HIF-1α expression was upregulated in hypoxia-induced PASMCs. ChIP-qPCR and dual-luciferase reporter gene assays confirmed that HIF-1α transcriptionally regulated and promoted miR-663b expression. Upregulation of miR-663b inhibited AMPK/Sirt1 signalling pathway activation and promoted ZBP1-mediated PANoptosis. However, miR-663b inhibitors reversed hypoxia-induced PANoptosis in PASMCs. The protective effects of miR-663b inhibitors on PASMCs and their inhibitory effects on PANoptosis were significantly weakened by treatment with an AMPK inhibitor or a Sirt1 inhibitor. Collectively, these findings suggest that inhibiting HIF-1α-mediated miR-663b expression improves PAH by reducing PASMC dysfunction through the attenuation of inflammatory responses, oxidative stress and apoptosis in PASMCs and the activation of the AMPK/Sirt1 pathway.