Cardioprotective Effect of the SDF-1α/CXCR4 Axis in Ischemic Postconditioning in Isolated Rat Hearts

Figure 1. Experimental protocol. CON group was subjected to 30 minutes of regional ischemia followed by 120 minutes of reperfusion. IPOC group was induced by 6 cycles of 10 seconds reperfusion and 10 seconds global ischemia immediately after reperfusion. CXCR4 antagonist AMD3100 was administered from 20 minutes before reperfusion to 30 minutes after reperfusion. CON = untreated control hearts (n=12); CXCR4 = chemokine receptor type 4; IPOC = ischemic postconditioning (n=8).

Figure 2. (A) Representative sequential LV slices from each group showing the AN (pale area) with TTC staining. (B) Percent of infarct area over AR. All data are expressed as mean±standard deviation. There were significant differences between p=0.021 vs. CON group and p=0.045 vs. AMD+IPOC group. AMD = AMD3100 treatment in CON (n=9); AMD+IPOC = CXCR4 antagonist AMD3100 treatment in IPOC (n=11); AN = area of necrosis; AR = area at risk; CON = untreated control hearts (n=12); IPOC = ischemic postconditioning (n=8); TTC = 2,3,5-triphenyltetrazolium chloride.

Figure 3. Coronary effluent LDH and CK measured at 60 minutes after reperfusion. Data are expressed as mean±standard deviation. p<0.050 vs. CON group. AMD = AMD3100 treatment in CON (n=9); AMD+IPOC = CXCR4 antagonist AMD3100 treatment in IPOC (n=11); CK = creatine kinase; CON = untreated control hearts (n=12); IPOC = ischemic postconditioning (n=8); LDH = lactate dehydrogenase.

Figure 4. Confocal image of representative immunofluorescent staining for SDF-1 (green), DAPI (blue, nuclear DNA), and merged image from isolated perfused rat hearts. AMD = AMD3100 treatment in CON (n=9); AMD+IPOC = CXCR4 antagonist AMD3100 treatment in IPOC (n=11); CON = untreated control hearts (n=12); DAPI = 4',6-diamidino-2-phenylindole; IPOC = ischemic postconditioning (n=8); SDF-1 = stromal cell-derived factor-1.

Figure 5. (A) Representative western blotting for p-Akt and t-Akt intensity. (B) Representative western blotting for p-ERK1/2 and t-ERK1/2 intensity. Bar graph shows percentage change in ERK1/2 and Akt phosphorylation relative to CON group. Increased phosphorylation of Akt and ERK1/2 in IPOC-induced hearts was totally blocked by AMD3100. Data are expressed as mean±standard deviation. p<0.050 vs. CON group. AMD = AMD3100 treatment in CON (n=9); AMD+IPOC = CXCR4 antagonist AMD3100 treatment in IPOC (n=11); CON = untreated control hearts (n=12); IPOC = ischemic postconditioning (n=8); p-Akt = phospho-Akt; p-ERK1/2 = phospho-extracellular signal-regulated kinase 1/2; t-Akt = total-Akt; t-ERK1/2 = total-extracellular signal-regulated kinase 1/2.