Knockdown of cardiac miR-21 expression abolishes IPost-mediated cardioprotection against I/R injury in vivo.

<p>(A) IPost-induced cardiac protection greatly reduced myocardial infarct size after 30 min myocardial ischemia followed by 3 h reperfusion. But antagomir-21 pre-treatment greatly increased myocardial infarct size. However, the region at risk was not significantly different among groups. Data are expressed as mean±SEM, n=5; ^**<i>P</i><0.01 compared with I/R group, ^{# #}<i>P</i><0.01 compared with IPost+I/R group; ^{† †}<i>P</i><0.01 compared with Antagomir-21+IPost+ I/R group. (B) Knockdown of cardiac miR-21 expression inhibited IPost-induced anti-apoptotic effect on cardiac Cells in Vivo. Quantitative analysis of the apoptotic cells in heart sections. (C) Representative TUNEL and α-actinin stained photomicrographs of cardiac myocytes in heart sections from the four groups of mice with different treatments. Note: green colour was TUNEL staining representing apoptotic cells; red colour was the α-actinin staining representing cardiac myocytes; blue colour was the cell nucleus stained by DAPI. Original magnification: ×400. Data are expressed as mean± SEM, n=5; ^**<i>P</i><0.01 compared with I/R group; ^{# #}<i>P</i><0.01 compared with IPost+I/R group; ^{† †}<i>P</i><0.01 compared with Antagomir-21+IPost+ I/R group.