Abstract：Objective: To investigate the effect of rhein on hypoxia-induced pulmonary hypertension (HPH) and its mechanism. Methods: Sprague-Daeley (SD) rats were used as the research objects. The SD rats separated into 3 groups: normoxia group (N), hypoxia group (H), hypoxia+rhein group (HR). The expressions of p-CDK9,CDK9, p-STAT3/STAT3, PCNA, Bcl-2, Bax, Caspase-3, CC-3 (Cleaved-Caspase-3) in lung homogenate were revealed by Western blot. The mean pulmonary artery pressure in 3 groups of rat was measured by right heart catheterization method. The degree of right cardiac hypertrophy was measured by weighing, while the degree of pulmonary vascular remodeling in each group of rats was observed by HE staining. Results: Compared with the N group, the p-CDK9, CDK9, p-STAT3/STAT3, PCNA, Bcl-2 protein expression in H group was increased (P<0.05), the Bax, Caspase-3, CC-3 protein expression in H group was reduced (P<0.05), the mPAP, right cardiac
hypertrophy index and WA/TA in H group were considerably enhanced (P<0.05). In contrast with the H group,the p-CDK9, CDK9, p-STAT3/STAT3, PCNA, Bcl-2 protein expression in HR group was reduced (P<0.05), the Bax, Caspase-3, CC-3 protein expression in HR group was considerably increased (P<0.05), the mPAP, right cardiac hypertrophy index and WA/TA in HR group were reduced (P<0.05). Conclusion: Rhein could inhibit the phosphorylation of STAT3 by inhibiting the expression and phosphorylation of CDK9, thereby alleviating pulmonary hypertension, improving pulmonary vascular remodeling and right heart hypertrophy in HPH rats.
