In the present study, we found that highglucose significantly increased expression of CHOP, ATF-6 and GRP78 compared withthe control group, indicating that high glucose induces ER stress in AF cells.However, when ER stress was inhibited by the inhibitor 4-PBA, expression of CHOP,ATF-6 and GRP78 was decreased, and AF cell apoptosis was attenuated. Here, HSPA5 is linked to atrial fibrillation.