Acute myocardial ischemia (AMI) was induced by occlusion of the left anterior descending (LAD) coronary artery in rats.AMI rats and normal rats were administered with protocatechuic aldehyde(Pal) at a single dose of 20 mg/kg through peritoneal injection.Concentrations of Pal,protocatechuic acid (PAC) and vanillic acid (VAC) in plasma were determined by HPLC to evaluate the effect of AMI on pharmacokinetics of Pal in rats.Pal was quickly metabolized to PAC,which was then methylated into VAC.Compared to the normal group,AUC_(0-∞) of PAC significantly increased from 14.01 ±3.11 to 22.31 ±4.96 μg·h/mL in AMI group (P ＜ 0.01),and AUC_(0-∞) of VAC markedly elevated from 19.64 ±4.36 to 38.76±5.75 μg·h/mL (P＜0.01).Both MRT of PAC and VAC increased (0.43 ± 0.08 h vs 0.27 ± 0.04 h,0.61 ± 0.11 h vs 0.38 ± 0.05 h,P ＜ 0.01).Metabolic ratio M/P of PAC increased from 1.43 ±0.31 to 1.77 ±0.22 (P ＜0.05).Results indicated that AMI status had great influence on pharmacokinetic behavior of Pal.Meanwhile,the level of methylation was greatly increased.