Cardioprotective role of APIP in myocardial infarction through ADORA2B

a–c Increase of both Apip and Adora2b transcripts in cardiac tissue from patients with heart failure. Apip (a) and Adora2b (b) transcripts in cardiac tissue from patients with heart failure or controls were quantified by real-time RT-PCR analysis (Control group: n？=？29, Heart failure patient group: n？=？18). Statistical significance was determined by Student’s t test. Levels of APIP and ADORA2B transcripts were plotted with mean Pearson correlation coefficient (0.912) (c). d APIP regulates ADORA2B in mice. Representative western blot showing ADORA2B protein levels in the heart of WT, APIPTg/Tg, APIPTg/+, and Apip+/？ mice at 4–5 months of age. e–g Increase of both Apip and Adora2b transcripts, and APIP protein in the hypoxic condition. Cultured primary cardiomyocytes were incubated with normoxic (Nor., 21% O2) or hypoxic (Hypo., 1% O2) condition for 6？h and total RNAs were analyzed by real-time RT-PCR analysis (**P？<？0.01, *P？<？0.05, two-tailed t test) (e). Cell lysates were analyzed by western blotting (f) and the signals on the blots were quantified by densitometric analysis (**P？<？0.01, *P？<？0.05, two-tailed t test) (g). h, i Reduction of infarct area in the heart of APIPTg/+ mice. APIPTg/+ mice or WT littermate were subjected to ligation of the left descending anterior coronary artery for 24？h and the hearts were then stained with Evans blue and 2,3,5-triphenyltetrazolium chloride (TTC). The Evans blue-perfused area, which is not at risk, was stained blue, viable myocardium was stained red, and infarcted myocardium appeared pale. The representative images are shown (h). AAR/LV indicates percentage of LV at risk, IA/AAR, infarcted area as percentage of risk area (Male, 12 weeks, n？=？8 mice per group, *P？<？0.05, N.S., not significant (P？>？0.05), one-way ANOVA/Bonferroni) (i). j–m Restoration of cardiac function in APIPTg/+ mice. APIPTg/+ mice and WT littermates are subjected to ligation of the left descending anterior coronary artery. Left ventricular (LV) chamber dimensions and systolic function were measured at 3 weeks after the ligation surgery. Typical echocardiographic M-mode images are shown (j). Data are represented as the mean？±？S.D. (male, 13–14 weeks, n？=？3 mice per group, **P？<？0.01, one-tailed t test). Parameters for cardiac function: FS fractional shortening, EF ejection fraction, LVIDs LV internal diameter at systole (k–m