Metabolic syndrome influences cardiac gene expression pattern at the transcript level in male ZDF rats

Background: Metabolic syndrome (coexisting visceral obesity, dyslipidemia, hyperglycemia, and hypertension) is a prominent risk factor for cardiovascular morbidity and mortality, however, its effect on cardiac gene expression pattern is unclear. Therefore, we examined the possible alterations in cardiac gene expression pattern in male Zucker Diabetic Fatty (ZDF) rats, a model of metabolic syndrome. Methods: Fasting blood glucose, serum insulin, cholesterol and triglyceride levels were measured at 6, 16, and 25 wk of age in male ZDF and lean control rats. Oral glucose tolerance test was performed at 16 and 25 wk of age. At week 25, total RNA was isolated from the myocardium and assayed by rat oligonucleotide microarray for 14921 genes. Expression of selected genes was confirmed by qRT-PCR. Results: Fasting blood glucose, serum insulin, cholesterol and triglyceride levels were significantly increased, glucose tolerance and insulin sensitivity were impaired in ZDF rats compared to leans. In hearts of ZDF rats, 36 genes showed significant up-regulation and 49 genes showed down-regulation as compared to lean controls. Genes with significantly altered expression in the heart due to metabolic syndrome includes functional clusters of metabolism (e.g. 3-hydroxy-3-methylglutaryl-Coenzyme A synthase 2; argininosuccinate synthetase; 2-amino-3ketobutyrate-coenzyme A ligase), structural proteins (e.g. myosin IXA; aggrecan1), signal transduction (e. g. activating transcription factor 3; phospholipase A2; insulin responsive sequence DNA binding protein-1) stress response (e.g. heat shock 70kD protein 1A; heat shock protein 60; glutathione S-transferase Yc2 subunit), ion channels and receptors (e.g. ATPase, (Na+)/K+ transporting, beta 4 polypeptide; ATPase, H+/K+ transporting, nongastric, alpha polypeptide). Moreover some other genes with no definite functional clusters were also changed such as e. g. S100 calcium binding protein A3; ubiquitin carboxy-terminal hydrolase L1; interleukin 18. Gene ontology analysis revealed several significantly enriched functional inter-relationships between genes influenced by metabolic syndrome. Conclusions: Metabolic syndrome significantly alters cardiac gene expression profile which may be involved in development of cardiac pathologies in the presence of metabolic syndrome

Preconditioning protects the heart in a prolonged uremic condition

Metabolic diseases such as hyperlipidemia and diabetes attenuate the cardioprotective effect of ischemic preconditioning. In the present study, we examined whether another metabolic disease, prolonged uremia, affects ischemia/reperfusion injury and cardioprotection by ischemic preconditioning. Uremia was induced by partial nephrectomy in male Wistar rats. The development of uremia was verified 29 wk after surgery. Transthoracic echocardiography was performed to monitor cardiac function. At week 30, hearts of nephrectomized and sham-operated rats were isolated and subjected to a 30-min coronary occlusion followed by 120 min reperfusion with or without preceding preconditioning induced by three intermittent cycles of brief ischemia and reperfusion. In nephrectomized rats, plasma uric acid, carbamide, and creatinine as well as urine protein levels were increased as compared with sham-operated controls. Systolic anterior and septal wall thicknesses were increased in nephrectomized rats, suggesting the development of a minimal cardiac hypertrophy. Ejection fraction was decreased and isovolumic relaxation time was shortened in nephrectomized rats demonstrating a mild systolic and diastolic dysfunction. Infarct size was not affected significantly by nephrectomy itself. Ischemic preconditioning significantly decreased infarct size from 24.8 ± 5.2% to 6.6 ± 1.3% in the sham-operated group and also in the uremic group from 35.4 ± 9.5% to 11.9 ± 3.1% of the area at risk. Plasma ANG II and nitrotyrosine were significantly increased in the uremic rats. We conclude that although prolonged experimental uremia leads to severe metabolic changes and the development of a mild myocardial dysfunction, the cardioprotective effect of ischemic preconditioning is still preserved

Nitrát tolerancia a szívizomban = Nitrate tolerance in the myocardium

Nagy dózisú nitroglicerin ismételt alkalmazásával vaszkuláris nitrát toleranciát váltottunk ki kísérleti állatokban. Kimutattuk hogy vaszkuláris nitrát toleranciában a szív és az aorta génexpressziós profilja eltérően változik. A szívizom génexpressziós változását egyéb szisztémás metabolikus állapotokban (metabolikus szindróma) is leírtuk. Kimutattuk, hogy az iszkémiás posztkondícionálás infarktus méretet csökkentő hatása jelentősen mérséklődik vaszkuláris nitrát tolerancia fennállása esetén. Továbbá azt tapasztaltuk, hogy ez a jelenség független a túlélő kinázok aktiválódásától. Kísérletes urémiában viszont a prekondícionálás kardioprotektív hatása megtartott marad. Izolált perfundált szívekben kimutattuk, hogy mind a koronária lekötés előtt, mind pedig a reperfúzió előtt megkezdett nitroglicerin perfúzió csökkenti a kialakuló infarktus méretét. Azonban a nitroglicerinnek ez a kardioprotektív hatása vaszkuláris nitrát tolerancia fennállása esetén nem volt megfigyelhető. Igazoltuk, hogy a NO-donor SNAP védi a szimulált iszkémia/reoxigenizációnak kitett primer szívizomsejt tenyészeteket a sejtelhalástól, valószínűleg részben a cGMP-PKG jelátviteli útvonal aktiválása révén. Továbbá kimutattuk, hogy a reperfúzió kezdetén alkalmazott szakaszos nagyfrekvenciás ingerléssel is kiváltható posztkondícionáló hatás a szívben. | We have induced vascular nitrate tolerance in rats by repeated administration of high dose nitroglycerin. We have found that the gene expression profile of the heart and the aorta was differentially altered in response to the development of vascular nitrate tolerance. Alterations in cardiac gene expression were shown in other systemic metabolic conditions (i.e. metabolic syndrome) as well. We have shown that the infarct size limiting effect of ischemic postconditioning is attenuated in the state of vascular nitrate tolerance. Moreover, we have found that this phenomenon is independent of survival kinase activation. Experimental uremia. however, did not lead to the loss of ischemic preconditioning. We have demonstrated in ex vivo hearts that nitroglycerin perfusion decreased infarct size when started before coronary occlusion and also when only started before reperfusion. This cardioprotective effect of nitroglycerin was diminished in the state of vascular nitrate tolerance. We have shown that the NO-donor molecule SNAP is able to protect primary cardiomyocyte cultures against simulated ischemia/reperfusion at least in part via activation of cGMP-PKG signaling. We have found that a postconditioning effect can be induced by applying short periods of ventricular overdrive pacing at the onset of reperfusion

MicroRNAs associated with ischemia/reperfusion injury and cardioprotection by ischemic pre- and postconditioning: ProtectomiRs

We aimed to characterize early changes in microRNA expression in acute cardioprotection by ischemic pre- and postconditioning in rat hearts. Hearts isolated from male Wistar rats were subjected to i) time-matched non-ischemic perfusion, ii) ischemia/reperfusion (30 min coronary occlusion and 120 min reperfusion), iii) preconditioning (3x5 min coronary occlusion) followed by ischemia/reperfusion, or iv) ischemia/reperfusion with postconditioning (6x10s global ischemia/reperfusion at the onset of reperfusion, respectively. Infarct size was significantly reduced by both interventions. Out of 350 different microRNAs assessed by microarray analysis, 147-160 showed detectable expression levels. As compared to microRNA alterations induced by ischemia/reperfusion vs. time-matched non-ischemic controls, 5 microRNAs were significantly affected by both pre- and postconditioning (microRNA-125b*, 139-3p, 320, 532-3p, 188), 4 microRNAs by preconditioning (microRNA-487b, 139-5p, 192, 212), and 9 by postconditioning (microRNA-1, let-7i, let-7e, let7b, 181a, 208, 328, 335, 503), respectively. Expression of randomly selected microRNAs was validated by QRT-PCR. By a systematic comparison of the direction of microRNA expression changes in all groups, we identified microRNAs, specific mimics or antagomiRs of which may have pre- and postconditioning-like cardioprotective effect (protectomiRs). Transfection of selected protectomiRs (mimics of microRNA-139-5p, -125b*, let-7b, and inhibitor of microRNA-487b) into cardiac myocytes subjected to simulated ischemia/reperfusion showed significant cytoprotective effect. This is the first demonstration that ischemia/reperfusion-induced microRNA expression profile is significantly influenced by both pre- and postconditioning, which shows the involvement of microRNAs in cardioprotective signaling. Moreover, by analysis of microRNA expression patterns in cardioprotection by pre- and postconditioning, specific protectomiRs can be revealed as potential therapeutic tools treating ischemia/reperfusion injury

Preconditioning protects the heart in a prolonged uremic condition

Metabolic diseases such as hyperlipidemia and diabetes attenuate the cardioprotective effect of ischemic preconditioning. In the present study, we examined whether another metabolic disease, prolonged uremia, affects ischemia/reperfusion injury and cardioprotection by ischemic preconditioning. Uremia was induced by partial nephrectomy in male Wistar rats. The development of uremia was verified 29 wk after surgery. Transthoracic echocardiography was performed to monitor cardiac function. At week 30, hearts of nephrectomized and sham-operated rats were isolated and subjected to a 30-min coronary occlusion followed by 120 min reperfusion with or without preceding preconditioning induced by three intermittent cycles of brief ischemia and reperfusion. In nephrectomized rats, plasma uric acid, carbamide, and creatinine as well as urine protein levels were increased as compared with sham-operated controls. Systolic anterior and septal wall thicknesses were increased in nephrectomized rats, suggesting the development of a minimal cardiac hypertrophy. Ejection fraction was decreased and isovolumic relaxation time was shortened in nephrectomized rats demonstrating a mild systolic and diastolic dysfunction. Infarct size was not affected significantly by nephrectomy itself. Ischemic preconditioning significantly decreased infarct size from 24.8 ± 5.2% to 6.6 ± 1.3% in the sham-operated group and also in the uremic group from 35.4 ± 9.5% to 11.9 ± 3.1% of the area at risk. Plasma ANG II and nitrotyrosine were significantly increased in the uremic rats. We conclude that although prolonged experimental uremia leads to severe metabolic changes and the development of a mild myocardial dysfunction, the cardioprotective effect of ischemic preconditioning is still preserved