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Figure 4 Time course of the protective effect of remote ischemic preconditioning (RIPC) on ischemia-reperfusion (IR)-induced endothelial dysfunction. Flow-mediated dilation (FMD) was 9.4 ± 0.7% at baseline (BL) and was unaffected by IR preceded immediately by RIPC (a) (IR+RIPC 8.0 ± 0.8%; p = NS vs. BL, analysis of variance [ANOVA]; n = 13). Ischemia-reperfusion reduced FMD when RIPC was applied 4 h before IR (b) (BL 8.6 ± 1.1% vs. IR+RIPC4 4.9 ± 1.1%; *p < 0.001, ANOVA; n = 10). However, the effect of IR to reduce FMD was prevented when RIPC was applied 24 h before IR (c) (BL 8.7 ± 1.1% vs. IR+RIPC24 8.4 ± 1.2%; p = NS, ANOVA; n = 12) and 48 h before IR (d) (BL 10.0 ± 0.9% vs. IR+RIPC48 8.8 ± 1.4%; p = NS, ANOVA; n = 8).