Pretreatment with probucol attenuates cardiomyocyte apoptosis in a rabbit model of ischemia/reperfusion

OBJECTIVE: Apoptosis plays an important role in ischemic reperfusion injury. Probucol is a hypolipidemic agent and has antioxidant activity, which may inhibit the oxidative modification of low-density lipoprotein cholesterol. Studies have demonstrated that probucol improves left ventricular function, prevents left ventricular dilatation, and reduces cardiac fibrosis. However, the exact mechanism of probucol on the cardioprotective effect is not known. The objective of the present study was to examine the effect of probucol on ischemia/reperfusion-induced cardiomyocyte apoptosis. MATERIAL AND METHODS: Thirty male New Zealand White rabbits were randomly divided into sham, control, and treated groups, each group comprising 10 rabbits. Before establishment of the ischemia/reperfusion model, animals in the treated group were additionally fed daily with probucol (1000 mg per day) for 4 weeks. In the sham group, the heart was exposed after the chest had been opened, but the coronary artery was not ligated. The animals were killed 150 min after the procedure. In the other two groups, the rabbits were subjected to 30-min of coronary occlusion followed by a 2-h reperfusion. A blood sample was drawn from the right atrium before the animal was killed. The apoptotic myocytes were detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling. Expression of caspase-3 and mitochondrial cytochrome c release was detected by immunohistochemical analysis and Western blot analysis. The level of serum superoxide dismutase (SOD) was tested using the xanthine oxidase method, and the content of serum malondialdehyde (MDA) was measured by colorimetry. RESULTS: As compared with the sham group, the control group had a significantly higher apoptotic index ((32.48 +/- 4.56) % versus (0.56 +/- 0.18) %, p < 0.01) and serum MDA concentration (2.70 +/- 0.64 versus 1.06 +/- 0.46 micromol/L, p < 0.01), and a significantly lower serum SOD level (144.27 +/- 21.69 versus 204.64 +/- 16.67 microU/L, p < 0.01). Probucol pretreatment apparently caused a decrease in the apoptotic index ((21.64 +/- 3.08) %, p < 0.01 versus the sham or control group) and serum MDA concentration (1.95 +/- 0.51 micromol/L, p < 0.01 versus the sham or control group), and increased the levels of serum SOD (162.61 +/- 16.13 microU/L, p < 0.01 versus the sham group; p < 0.05 versus the control group). The caspase-3 activation and mitochondrial cytochrome c release in the control group were also higher than those in the treated group (p < 0.01). CONCLUSIONS: The present study shows that probucol attenuates ischemia/reperfusion-induced cardiomyocyte apoptosis. The protective effect of probucol on the myocardium may be partly due to its antioxidant activity.