Effect of apocynin on L-type calcium current and action potential duration in rabbit atrial myocytes under oxidative stress in vitro

  Background  The occurrence and development of atrial fibrillation is complex. A large number of studies have shown that oxidative stress is closely related to atrial fibrillation. Apocynin (APO) is an important oxidase inhibitor in the process of oxidative stress injury, which can resist oxidative stress injury.

  Objective  To study the protective effect of apocynin on L-type calcium current (I_Ca,L) and action potential duration (APD) in rabbit left atrial myocytes under oxidative stress injury.

  Methods   We used enzyme to get single left atrial myocytes of rabbit, and they were divided into control group (n=13), H₂O₂(10 μmol/L) group (n=13), H₂O₂ (50 μmol/L) group (n=13), H₂O₂ (50 μmol/L) + APO (100 μmol/L) group, APO (100 μmol/L) group (n=13). The whole cell patch clamp technique was used to study the protective effect of APO on I_Ca,L and APD under oxidative stress injury. Real-time qPCR and Western blot were used to detect the expression of CACNA1C mRNA and Ca_V1.2 protein levels.

  Results   In the H₂O₂ (10 μmol/L) group, the peak value of I_Ca,L declined from (−18.5±0.1) pA/pF to (−10.7±0.7) pA/pF (P＜0.01); In the H₂O₂ (50 μmol/L) group, the peak value of I_Ca,L declined from (−18.5±0.1) pA/pF to (−9.4±0.8) pA/pF (P＜0.01); In H₂O₂ (50 μmol/L) + APO (100 μmol/L) group, the peak value of I_Ca,L was (−16.7±1.6) pA/pF, significantly higher than that in the H₂O₂ (50 μmol/L) group after treatment (P＜0.01); In APO (100 μmol/L) group, the peak of I_Ca,L was (−17.2±1.3) pA/pF, similar to the control group (P＞0.01). APO also recovered the shortened APD₅₀ induced by H₂O₂. Compared with H₂O₂ group, the expression of CACNA1C mRNA and the protein levels of Ca_V1.2 decreased (P＜0.05), which could be recovered by APO.

  Conclusion   APO have the protective effect on I_Ca,Land APD in left atrial myocytes of rabbit.