Cardioprotection against ischaemia/reperfusion damage in mice may be accomplished by delayed ischaemic postconditioning (IPost) applied while late while 30?min following the starting point of reperfusion. when used over time of myocardial ischaemia enduring 30?min. Delayed IPost used after 30 or 45?min of reperfusion reduced infarct sizes by 36 and 41?% respectively (both shows period of intravenous administration from the inhibitors of RISK [PD-98059 (PD) LY-294002 (LY)] or Safe and sound pathways [AG490 (AG)]. b LY and PD abolished cardioprotection founded by instant … Immunoblotting for success kinases Within an additional group of tests rats underwent 30?min of myocardial ischaemia as well as the hearts were collected in 15?min after sham-IPost or IPost (6 cycles of We/R 10 applied 10?s 10 or 45?min after reperfusion starting point. Rats were randomly assigned to one of the following six groups: BMS 626529 sham-immediate IPost (sham-IPost10″ indicates time of intravenous administration of the mitochondrial KATP channel blocker 5-hydroxydecanoate (5-HD). b 5-HD abolished cardioprotection established by immediate (IPost10″) and early … Statistical analysis Data are reported as mean?±?SD. Data were compared by ANOVA followed by Tukey-Kramer post hoc test or unpaired test as appropriate. Values of P?0.05 were considered to be significant. Results No differences in mean arterial blood pressure or heart rate before or during BMS 626529 ischaemia and reperfusion were observed between groups of animals recruited into the experimental protocols (data not shown). There were also no differences in the areas BMS 626529 at risk between experimental groups (mean values of areas at risk ranged between 39 and 43?%). Figures?1c d ?d 2 and ?and4b4b illustrate infarct sizes expressed as percentages of the area at risk. Efficacy of immediate early and delayed IPost in conferring cardioprotection against myocardial ischaemia/reperfusion injury and its dependence upon the duration of the ischaemic period. Infarct sizes in animals subjected to DP1 20 30 and 45?min of LAD occlusion followed by 120?min BMS 626529 of reperfusion BMS 626529 were 33?±?3 44 and 51?±?8?% respectively (Fig.?1c). Infarcts in animals subjected to 45?min of ischaemia were significantly larger than in animals subjected to 20?min of ischaemia (P?0.05) (Fig.?1c). IPost reduced infarct sizes by 43?% (P?0.01) and 31?% (P?0.05) when applied either 10?s or 10?min after the end of myocardial ischaemia which had the duration of 30?min (Fig.?1c). IPost failed to reduce the infarct size when applied 10?s or 10?min following periods of myocardial ischaemia lasting either 20 or 45?min (Fig.?1c). Delayed IPost applied either 30?min or 45?min after the onset of reperfusion effectively reduced infarct size by 36?% (P?0.01) and 41?% (P?0.01) respectively (Fig.?1d). IPost applied after 60?min of reperfusion was ineffective (Fig.?1d). The role of RISK and SAFE pathways in cardioprotection established by IPost To determine whether activation of RISK and SAFE pathways is responsible for IPost cardioprotection we compared the infarct sizes in rats subjected to 30?min of LAD occlusion followed in 10?s or 10?min by IPost in control conditions (injections of vehicle) and after systemic administration of ERK1/2 inhibitor PD-98059 PI3K inhibitor LY-294002 or JAK/STAT pathway inhibitor AG490 (Fig.?2b). In the vehicle-treated group infarct size was 43?±?3?%. Both PD-98059 and LY-294002 abolished cardioprotection induced by immediate IPost applied 10?s after ischaemia (infarct size 44?±?4 and 41?±?3?% respectively both P?0.01 vs IPost10″ Fig.?2b) but had no effect on cardioprotection conferred by early IPost applied 10?min after reperfusion onset (infarct size 24?±?3 and 23?±?4?% respectively both n.s. vs IPost10′ Fig.?2b). AG490 had no effect on cardioprotection conferred by either immediate or early IPost (infarct size 25?±?3 and 25?±?6?% respectively both n.s. vs IPost10″ and IPost10′ respectively Fig.?2b). Western blot analysis revealed significant stimulatory effect of immediate IPost (10?s of reperfusion) on AKT and ERK1/2 (p42/p44 MAPK) phosphorylation (Fig.?3). Early (10?min of.