Protective role of deoxyschizandrin and schisantherin A against myocardial ischemia-reperfusion injury in rats.

BackgroundOur previous studies suggested that deoxyschizandrin (DSD) and schisantherin A (STA) may have cardioprotective effects, but information in this regard is lacking. Therefore, we explored the protective role of DSD and STA in myocardial ischemia-reperfusion (I/R) injury.Methodology/principal findingsAnesthetized male rats were treated once with DSD and STA (each 40 µmol/kg) through the tail vein after 45 min of ischemia, followed by 2-h reperfusion. Cardiac function, infarct size, biochemical markers, histopathology and apoptosis were measured and mRNA expression of gp91 (phox) in myocardial tissue assessed by RT-PCR. Neonatal rat cardiomyocytes were pretreated with DSD and STA and then damaged by H2O2. Cell apoptosis was tested by a flow cytometric assay. Compared with the I/R group: (i) DSD and STA could significantly reduce the abnormalities of LVSP, LVEDP, ±dp/dtmax and arrhythmias, thereby showing their protective roles in cardiac function; (ii) DSD and STA could significantly attenuate the infarct size and MDA release while increasing SOD activity, suggesting a role in reducing myocardial injury; (iii) tissue morphology and myocardial textual analysis revealed that DSD and STA mitigated changes in myocardial histopathology; (iv) DSD and STA decreased apoptosis (33.56±2.58% to 10.28±2.80% and 10.98±1.99%, respectively) and caspase-3 activity in the myocardium (0.62±0.02 OD/mg to 0.38±0.02 OD/mg and 0.32±0.02 OD/mg, respectively), showing their protective effects upon cardiomyocytes; and (v) DSD and STA had similar protective effects on I/R injury as those seen with the positive control metoprolol. In vitro, DSD and STA could significantly decrease the apoptosis of neonatal cardiomyocytes.Conclusions/significanceThese data suggest that DSD and STA can protect against myocardial I/R injury. The underlining mechanism may be related to their role in inhibiting cardiomyocyte apoptosis

Examples of ventricular tachycardia (VT) and ventricular fibrillation (VF).

<p>A shows sustained VT of regular morphology and rate. B shows one example of terminal VF. Scale bar, 300 ms.</p

Activity of caspase-3 in the myocardial tissues of rats of various groups.

<p>Traces of the mean values (± SD, vertical lines). ^&&<i>P</i><0.01 <i>vs</i> I/R, ^**<i>P</i><0.01 <i>vs</i> metoprolol.</p

Effects of various administrations on mortality and arrhythmias on ischemia–reperfusion-induced arrhythmias in rats.

<p>Data are the mean ± SD. Values marked with ^&&<i>P</i><0.01 are significantly different from I/R. Values marked with * <i>P</i><0.05 or ** <i>P</i><0.01 are significantly different from metoprolol.</p

Effects of various administrations upon hemodynamics in a model of ischemia–reperfusion in rats.

<p>Data are the mean ± SD. Values marked with ^&&<i>P</i><0.01 are significantly different from I/R. Values marked with * <i>P</i><0.05 or ** <i>P</i><0.01 are significantly different from metoprolol. Values marked with ^†<i>P</i><0.05 or ^‡<i>P</i><0.01 are significantly different from baseline. LVSP, LVEDP and ± d<i>p</i>/dt_max represent left ventricular systolic pressure, left ventricular end-diastolic pressure, and the maximal rates of increase and decrease in LV pressure, respectively.</p

Effect on serum MDA levels and SOD activity after I/R injury in each group of rats.

<p>Serum samples were collected after 2 h of reperfusion; MDA concentrations were assayed according to the thiobarbituric acid (TBA) method (A); SOD activities were measured by the xanthine oxidase method (B). Traces of the mean values (± SD, vertical lines). ^&&<i>P</i><0.01 <i>vs</i> I/R, ^**<i>P</i><0.01 <i>vs</i> metoprolol.</p

Percentages of positive nuclei in the myocardial tissues of various groups.

<p>(A) Representative photomicrographs of <i>in situ</i> detection of DNA fragments from sham-operated rats or rats with different pretreatments subjected to 45 min of ischemia followed by 2 h of reperfusion. Arrowheads indicate positive nuclei for TUNEL staining (magnification, ×250). (B) Bar graph shows the percentages of TUNEL-positive nuclei in sham, I/R and treated groups. Traces of the mean values (± SD, vertical lines). ^&&<i>P</i><0.01 <i>vs</i> I/R, ^**<i>P</i><0.01 <i>vs</i> metoprolol. Scale bar, 40 µm.</p

Gp91<i>^phox</i> mRNA level was analyzed by real-time RT-PCR on extracted total RNA.

<p>Threshold cycles (Ct values) were normalized to their corresponding GAPDH mRNA and the comparative mRNA levels determined by the ΔΔCt method. Traces of the mean values (± SD, vertical lines). ^&&<i>P</i><0.01 <i>vs</i> I/R.</p

Infarct size in rats of various groups subjected to I/R injury.

<p>Representative illustrations of infarct size as stained by Evans Blue and TTC (A). Bar graphs show AAR as a percentage of the LV (B) and An as a percentage of the AAR (C). Traces of the mean values (± SD, vertical lines). ^&&<i>P</i><0.01 <i>vs</i> I/R, ^**<i>P</i><0.01 <i>vs</i> metoprolol.</p