Protein kinase A-mediated cardioprotection of Tongxinluo relates to the inhibition of myocardial inflammation, apoptosis, and edema in reperfused swine hearts

Background Our previous studies have demonstrated that Tongxinluo （TXL）, a traditional Chinese medicine, can protect hearts against no-reflow and reperfusion injury in a protein kinase A （PKA）-dependent manner. The present study was to investigate whether the PKA-mediated cardioprotection of TXL against no-reflow and reperfusion injury relates to the inhibition of myocardial inflammation, edema, and apoptosis. Methods In a 90-minute ischemia and 3-hour reperfusion model, minipigs were randomly assigned to sham, control, TXL （0.05 g/kg, gavaged one hour prior to ischemia）, and TXL ＋ H-89 （a PKA inhibitor, intravenously and continuously infused at 1.0 μg/kg per minute） groups. Myocardial no-reflow, necrosis, edema, and apoptosis were determined by pathological and histological studies. Myocardial activity of PKA and myeloperoxidase was measured by colorimetric method. The expression of PKA, phosphorylated cAMP response element-binding protein （p-CREB） （Ser133）, tumor necrosis factor a （TNF-a）, P-selectin, apoptotic proteins, and aquaporins was detected by Western blotting analysis. Results TXL decreased the no-reflow area by 37.4% and reduced the infarct size by 27.0% （P〈0.05）. TXL pretreatment increased the PKA activity and the expression of Ser133 p-CREB in the reflow and no-reflow myocardium （P 〈0.05）. TXL inhibited the ischemia-reperfusion-induced elevation of myeloperoxidase activities and the expression of TNF-a and P-selectin, reduced myocardial edema in the left ventricle and the reflow and no-reflow areas and the expression of aquaporin-4, -8, and -9, and decreased myocytes apoptosis by regulation of apoptotic protein expression in the reflow and no-reflow myocardium. However, addition of the PKA inhibitor H-89 counteracted these beneficial effects of TXL. Conclusion PKA-mediated cardioprotection of TXL against no-reflow and reperfusion injury relates to the inhibition of myocardial inflammation, edema, and apoptosis in the reflow and no-reflow myocardium.