n?=?6/group
n?=?6/group. vehicle-treated MI hearts, p?0.05) post MI. In isolated working hearts an increase in insulin-stimulated glucose oxidation was evident in the mAb A-treated MI hearts (1661??192 vs 924??165?nmol?g dry wt?1?min?1 in vehicle-treated MI hearts, p?0.05), concomitant with a decrease in ketone oxidation and fatty acid oxidation rates. The increase in insulin stimulated glucose oxidation was accompanied by activation of the IRS-1/Akt/AS160/GSK-3 pathway, an increase in GLUT4 expression and a reduction in pyruvate dehydrogenase phosphorylation. This enhancement in insulin sensitivity occurred in parallel with a reduction in cardiac branched chain amino acids content (374??27 vs 183??41?mol?g protein?1 in vehicle-treated MI hearts, p?0.05) and inhibition of the mTOR/P70S6K hypertrophic signalling pathway. The MI-induced increase in the phosphorylation of transforming growth factor -activated kinase 1 (p-TAK1) and p38 MAPK was also reduced by mAb A treatment. Conclusions mAb A-mediated cardioprotection post-myocardial infarction is associated with improved insulin sensitivity and a selective enhancement of glucose oxidation via, at least in part, enhancing branched chain amino acids catabolism. Antagonizing glucagon action represents a novel and effective pharmacological intervention to alleviate cardiac dysfunction and adverse remodelling post-myocardial infarction. for 5?min and the supernatant (cleaned lysate) was collected. The protein sample was then incubated with anti-acetyl-lysine antibody (2?L, Millipore Sigma) overnight then 30?L of A/G PLUS-Agarose beads was added to the solution and incubated for 6?h. Samples were centrifugated at 5000for 5?min and the pellet was washed three times with the homogenisation buffer. Laemmli buffer was then added to the pellet and the mixture, heated at 95?C for 5?min then centrifuged at 15,000for 15?min. The supernatant was carefully eluted, and Pim1/AKK1-IN-1 the proteins were blotted following the same protocol for immunoblotting in the previous section. Negative control sample (?C) contained A/G PLUS-Agarose beads and anti-acetyl-lysine antibody with no protein sample, while positive control sample Pim1/AKK1-IN-1 (+C) contained protein sample and Laemmli buffer which has not been incubated with either A/G PLUS-Agarose beads or anti-acetyl-lysine antibody. Statistical analysis Data are reported as mean??SEM and were subjected to KolmogorovCSmirnov test for normal distribution. An unpaired, 2-tailed Student test was used to compare between two experimental groups, while one-way or two-way ANOVA were used for multiple comparisons with Bonferroni as a post hoc test. The difference between groups was considered significant when the p-value?0.05. GraphPad Prims? 7 software was used to draw all the figure and to conduct the statistical analysis. Results mAb A treatment improves cardiac function in the post-MI heart Mice were studied 4?weeks after being subjected to a permanent LAD ligation (Fig.?1a). A significant reduction in the % ejection fraction (%EF) and fractional shortening (FS%) was observed by 4?weeks post-MI in vehicle-treated mice (30.7??1.8% vs 62.8??1.4% and 7.6??1.0% vs 20.0??1.8% in the sham mice, p?0.05, respectively, Fig.?1b, c). However, a 3-week treatment with mAb A significantly improved Rabbit Polyclonal to C-RAF the %EF post-MI (39.71??2.3%, p?0.05, Fig.?1b) and fractional shortening (11.8??1.0%, p?0.05 Fig.?1c). In addition, myocardial dilation was observed in the post-MI mice hearts, with mAb A treatment attenuating this dilation (Fig.?1 d, e). No detectable changes in tissue doppler of the mitral valve E/A ratio were in seen in mAb A treated mice compared to vehicle-treated mice (Fig.?1f), although E/E ratio was significantly improved in the mAb A-treated MI mice (28.4??2.8?mm?s?1 vs 32.5??2.7?mm?s?1 vehicle-treated post MI mice, p?0.05, Fig.?1g). Consistent with the in vivo heart function, ex vivo cardiac work in the isolated working hearts from post-MI mice was decreased relative to sham mice (Fig.?1h) and was also improved by mAb A treatment (Fig.?1h). mAb A treatment inhibits cardiac hypertrophy and the mTOR signalling pathway Cardiac hypertrophy was observed in vehicle-treated MI mice compared to vehicle-treated sham mice Pim1/AKK1-IN-1 (Fig.?2a). This hypertrophy was accompanied by the activation of cardiac mTOR (Fig.?2c), and an increased phosphorylation of P70S6KThr389, a downstream effector of mTOR (Fig.?2d). mAb A treatment limited cardiac hypertrophy, an effect which was associated with abrogating mTOR/P70S6K signalling (Fig.?2bCd). In addition, a decrease in cardiac SERCA2A expression was observed in the post-MI.
