C3 and atrial fibrillation: In contrast, C3 deposition increased significantly after cold stress (10.78 ± 2.16, P = 0.000), however, pretreatment with 15 mg/kg (6.18 ± 0.39, P = 0.006) and 30 mg/kg (5.45 ± 0.60, P = 0.003) AF significantly reduced the C3 levels on erythrocyte membranes, suggesting that AF might inhibit the activation of the complement pathway in lung tissue after cold exposure.