〔Abstract〕 Abstract Objective To investigate the effects of heat shock protein 70 ku protein 1A (HSPA1A) on H9c2 in- flammation and apoptotic injury in rat cardiomyocytes under hypoxia , and to analyze its mechanism . Methods H9c2 cells were treated with normal oxygen (Nor) and hypoxia (Hyp) , and the expression of HSPA1A was detec- ted by RT-qPCR and Western blot. Normal H9c2 cells were divided into Nor group (normoxia culture) , sh-HS- PA1A + Nor group (cells transfected with HSPA1A shRNA , normoxia culture) , Hyp group (hypoxia culture) , sh- HSPA1A + Hyp group (cells transfected with HSPA1A SHRNA , hypoxia culture) , the expression level of HSPA1A in H9c2 cells in each group was detected by RT-qPCR and Western blot , the morphology of H9c2 cells in each group was observed by inverted microscope , and the activity of H9c2 cells in each group was detected by CCK-8 , the contents of inflammatory factors tumor necrosis factor-α(TNF-α) , interleukin(IL)-6 , IL-1βand the activities of myocardial injury markers lactate dehydrogenase (LDH) , creatine kinase (CK) in the supernatant of H9c2 cells were detected by ELISA , apoptosis rate of H9c2 cells in each group was detected by Annexin V-FITC/PI double staining , the expression levels of TNF receptor-associated factor 2 (TRAF2) /nuclear factor κB (NF-κB) pathway- related proteins in H9c2 cells of each group were detected by Western blot. Results Compared with Nor group , the relative expression of HSPA1A mRNA and protein in H9c2 cells in Hyp group after hypoxia induction was sig- nificantly up-regulated (P < 0. 05) . Compared with Nor group , the number of H9c2 cells in Hyp group significant- ly decreased , some cells were wrinkled and disordered , the cell activity significantly decreased ( P < 0. 05) , the contents of TNF-α, IL-6 , IL-1βand the activities of LDH and CK in supernatant significantly increased ( P < 0. 05) , the cell apoptosis rate significantly increased (P < 0. 05) , the relative expressions of TRAF2 protein and the phosphorylation level of p65 and inhibitor of nuclear factor κB alpha (IκBα) were significantly up-regulated (P < 0. 05) ; compared with Hyp group , the morphology of H9c2 cells in sh-HSPA1A + Hyp group was improved , the cell arrangement was more dense , the cell activity significantly increased (P < 0. 05) , the contents of TNF-α, IL- 6 and IL-1βin supernatant decreased , the activities of LDH and CK significantly decreased (P < 0. 05) , the apop- tosis rate significantly decreased ( P < 0. 05) , the relative expressions of TRAF2 protein and the phosphorylation level of p65 and IκBαwere also significantly down-regulated ( P < 0. 05 ) . Conclusion The expression of HS- PA1A in rat cardiomyocytes H9c2 is increased by hypoxia , and inhibition of HSPA1A expression can improve the hypoxia-induced inflammatory response of H9c2 cells and reduce apoptosis damage , which may be related to the regulation of TRAF2/NF-κB pathway .