Sildenafil augments early protective transcriptional changes after ischemia in mouse myocardium

Recently, targeting cyclic-GMP specific phosphodiesterase-5 (PDE5) has attracted much interest in several cardiopulmonary diseases, in particular myocardial ischemia (MI). Although multiple mechanisms were postulated for these beneficial effects at cellular level, early transcriptional changes were unknown. The aim of present study was to examine gene expression profiles in response to MI after 24 h of ischemia in murine model and compare transcriptional modulation by sildenafil, a popular phosphodiesterase 5 (PDE5) inhibitor. Mice were divided into four groups: Control sham (C), Sildenafil sham (S), Control MI (CMI) and Sildenafil MI (SMI). Sildenafil was given at a dose of 0.7 mg/kg intraperitoneally 30 min before LAD occlusion. cDNA microarray analysis of peri-infarct tissue was done using a custom cloneset and employing a looped dye swap design. Replicate signals were median averaged and normalized using LOWESS algorithm. R/MAANOVA analysis was used and false discovery rate corrected permutation p-values <0.005 were employed as significance thresholds. 156 genes were identified as significantly regulated demonstrating fold difference >1.5 in at least one of the four groups. 52 genes were significantly upregulated in SMI compared to CMI. For a randomly chosen subset of genes (9), microarray data were confirmed through real time RT-PCR. The differentially expressed genes could be classified into following groups based on their function: phosphorylation/dephosphorylation, apoptosis, differentiation, ATP binding. Our results suggest that sildenafil treatment might regulate early genetic reprogramming strategy for preservation of the ischemic myocardium.