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The aim of the present study was to examine the post-infarct acute effect of adenosine-5'-triphosphate (ATP) on myocardial infarction (MI) size as well as its precise molecular mechanism. Sixty New Zealand white male rabbits were exposed to 40 min of ischemia followed by 180 min of reperfusion. The rabbits were intravenously administered 3 mg/kg of ATP (ATP group) or saline (control group) immediately after reperfusion and maintained throughout the first 30 min. The wortmannin+ATP, PD-98059+ATP, and 5-hydroxydecanoic acid (5-HD) sodium salt+ATP groups were separately injected with wortmannin (0.6 mg/kg), PD-98059 (0.3 mg/kg), and 5-HD (5 mg/kg) 5 min prior to ATP administration. MI size was calculated as the percentage of the risk area in the left ventricle. Myocardial apoptosis was determined using a TUNEL assay. Western blot analysis was performed to examine the levels of protein kinase B (Akt)/ p-Akt and extracellular signal-regulated kinase (ERK)/p-ERK in the ischemic myocardium, 180 min after reperfusion. The infarct size was significantly smaller in the ATP group than in the control group (p<0.05). The infarct size-reducing effect of ATP was completely blocked by wortmannin, PD-98059 and 5-HD. Compared with the control group, cardiomyocyte apoptosis was significantly reduced in the ATP group, while this did not occur in the wortmannin+ATP, PD-98059+ATP and 5-HD+ATP groups. Western blot analysis revealed a higher myocardial expression of p-Akt and p-ERK 180 min following reperfusion in the ATP versus the control group. In conclusion, cardioprotection by postischemic ATP administration is mediated through activation of the reperfusion injury salvage kinase (RISK) pathway and opening of the mitochondrial ATP-dependent potassium channels. [ABSTRACT FROM AUTHOR]

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is an enzyme that hydrolyzes oxidized phospholipids to generate bioactive proatherogenic products. Nonculprit lesions have been assumed to contribute to the pathogenesis of recurrent acute coronary syndrome (ACS). The role of LP-PLA2 in the progression of nonculprit coronary lesions after successful percutaneous coronary intervention (PCI) remains unclear. Our study included 123 patients with ACS who underwent initial PCI and a long-term follow-up (mean interval, one year) with coronary angiography. Among them, 19 patients were diagnosed as the progression of nonculprit lesions, based on the presence of at least one of the following factors: (1) ≥ 10% reduction in the diameter of a preexisting ≥ 50% stenosis; (2) ≥ 30% reduction in the diameter of a < 50% stenosis; and (3) early-onset stenosis with ≥ 30% reduction in the diameter of a segment that was normal on the primary angiogram. Blood sampling was drawn from all patients at 12-14 hours after PCI. The ACS patients with progression had higher total cholesterol (4.47 ± 1.02 mmol/L vs. 3.59 ± 0.57 mmol/L, P < 0.05), higher levels of Lp-PLA2 activity (14.39 ± 6.13 nmol/min/ml vs. 8.86 ± 3.14 nmol/min/ml, P < 0.001) and a higher proportion of multi-vessel disease than those without progression. Multivariate logistic regression analysis showed that Lp-PLA2 activity ( β = 0.024, P = 0.005) was an independent predictor for rapid progression of nonculprit coronary lesions. In conclusion, elevated Lp-PLA2 activity is associated with rapid progression of nonculprit coronary lesions in ACS patients who underwent PCI. [ABSTRACT FROM AUTHOR]