The cardioprotective effect of thymoquinone on ischemia-reperfusion injury in isolated rat heart via regulation of apoptosis and autophagy.

Thymoquinone (TQ), as the active constituents of black cumin (Nigella sativa) seed oil, has been reported to have potential protective effects on the cardiovascular system. This study aimed to investigate the effects and the underlying mechanisms of TQ on myocardial ischemia-reperfusion (I/R) injury in Langendorff-perfused rat hearts. Wister rat hearts were subjected to I/R and the experimental group were pretreated with TQ prior to I/R. Hemodynamic parameters, myocardial infarct size, cardiac marker enzymes, superoxide dismutase (SOD), malondialdehyde (MDA) content, and cardiomyocyte apoptosis were assayed. Compared with the untreated group, TQ preconditioning significantly improved cardiac function, reduced infarct size, decreased cardiac lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) levels, suppressed enedoxidative stress, and apoptosis. In addition, TQ treatment promoted autophagy, which was partially reversed by chloroquine (CQ), a kind of autophagy blocker. Our study suggests that TQ can protect heart against I/R injury, which is associated with anti-oxidative and anti-apoptotic effects through activation of autophagy.

Resveratrol attenuates myocardial ischemia/reperfusion injury through up-regulation of vascular endothelial growth factor B.

The objective was to examine the protective effect of resveratrol (RSV) on myocardial ischemia/reperfusion (IR) injury and whether the mechanism was related to vascular endothelial growth factor B (VEGF-B) signaling pathway. Rat hearts were isolated for Langendorff perfusion test and H9c2 cells were used for in vitro assessments. RSV treatment significantly improved left ventricular function, inhibited CK-MB release, and reduced infarct size in comparison with IR group ex vivo. RSV treatment markedly decreased cell death and apoptosis of H9c2 cells during IR. We found that RSV was responsible for the up-regulation of VEGF-B mRNA and protein level, which caused the activation of Akt and the inhibition of GSK3ß. Additionally, RSV prevented the generation of reactive oxygen species (ROS) by up-regulating the expression of MnSOD either in vitro or ex vivo. We also found that the inhibition of VEGF-B abolished the cardioprotective effect of RSV, increased apoptosis, and led to the down-regulation of phosphorylated Akt, GSK3ß, and MnSOD in H9c2 cells. These results demonstrated that RSV was able to attenuate myocardial IR injury via promotion of VEGF-B/antioxidant signaling pathway. Therefore, the up-regulation of VEGF-B can be a promising modality for clinical myocardial IR injury therapy.

Sitagliptin attenuates cardiomyopathy by modulating the JAK/STAT signaling pathway in experimental diabetic rats.

Sitagliptin, a dipeptidyl peptidase-4 inhibitor, has been reported to promote cardioprotection in diabetic hearts by limiting hyperglycemia and hyperlipidemia. However, little is known about the involvement of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway modulation in the cardioprotective effects of sitagliptin. The current study aimed to investigate the protective effects of sitagliptin against diabetic cardiomyopathy (DCM), focusing on the modulation of the JAK/STAT pathway. Diabetes was induced by streptozotocin injection, and rats received sitagliptin orally and daily for 90 days. Diabetic rats exhibited hyperglycemia, hyperlipidemia, and a significant increase in heart-to-body weight (HW/BW) ratio. Serum troponin I and creatine kinase MB, cardiac interleukin-6 (IL-6), lipid peroxidation, and nitric oxide levels showed significant increase in diabetic rats. In contrast, both enzymatic and nonenzymatic antioxidant defenses were significantly declined in the heart of diabetic rats. Histopathological study revealed degenerations, increased collagen deposition in the heart of diabetic rats. Sitagliptin alleviated hyperglycemia, hyperlipidemia, HW/BW ratio, histological architecture, oxidative stress, and inflammation, and rejuvenated the antioxidant defenses. In addition, cardiac levels of pJAK2 and pSTAT3 were increased in diabetic rats, an effect which was remarkably decreased after sitagliptin treatment. In conclusion, these results confer an evidence that sitagliptin has great therapeutic potential on DCM through down-regulation of the JAK/STAT signaling pathway.

Development and performance of an enzyme immunoassay to detect creatine kinase isoenzyme MB activity using anti-mitochondrial creatine kinase monoclonal antibodies.

OBJECTIVE: The MB fraction of creatine kinase (CK-MB) has long been used as a cardiac marker. It is known that the CK-MB immunoinhibition method lacks selectivity and accuracy, because the appearance of macro CK type 2, corresponding to mitochondrial creatine kinase (MtCK) in some patient serum may render CK-MB activity measured by conventional method abnormally high. Thus, to improve the specificity and accuracy of the CK-MB assay, we developed two types of monoclonal anti-MtCK antibodies against sarcomeric MtCK and ubiquitous MtCK, and present herein the performance of a new method using these antibodies. MATERIAL AND METHODS: The performance of our test for detecting CK-MB activity was compared with other methods, and the range of CK-MB activities in normal human serum was investigated. RESULTS: The two types of monoclonal antibodies developed by us were isoenzyme-specific to sMtCK or uMtCK. The correlation coefficients of our method and conventional method to electrophoresis were 0.973 and 0.873, respectively. The mean CK-MB activity in normal human serum by our method and the conventional method was 2.4 and 11.7 U/L, respectively. Thus, our data indicated that about 80% of CK-MB activity, determined using the conventional method, seems to correspond to the MtCK activity. CONCLUSION: Our method is novel in offering higher accuracy of measuring true CK-MB contents in human serum as compared to the conventional method. The possibility of accurately estimating CK-MB activity by our method which can inhibit MtCKs in healthy person and patient serum is likely to bring a break-through in clinical diagnostics.

Ginsenoside Rb1 preconditioning protects against myocardial infarction after regional ischemia and reperfusion by activation of phosphatidylinositol-3-kinase signal transduction.

BACKGROUND: Ginsenoside Rb1, a major bioactive component of Panax ginseng, bears various beneficial effects on the cardiovascular system. This study investigated whether ginsenoside Rb1 preconditioning has protective effects on myocardial ischemia-reperfusion injury and its potential mechanism. METHODS: Rats subjected to 45 min of myocardial ischemia followed by 120 min of reperfusion were assigned to the following groups: sham-operated, ischemia-reperfusion (I/R), ginsenoside Rb1+I/R, wortmannin(a specific PI3K inhibitor)+I/R, wortmannin drug vehicle (dimethyl sulfoxide, DMSO), wortmannin+sham, ginsenoside Rb1+ wortmannin +I/R. Infarct size was assessed by triphenyltetrazolium chloride staining. Plasma creatine kinase (CK), creatine kinase isoenzyme MB (CK-MB), lactate dehydrogenase (LDH), and troponin T levels were also measured. Akt phosphorylation expression was assessed by immunoblotting. RESULTS: Ginsenoside Rb1 preconditioning reduced infarct size compared with that in the I/R group: 30 +/- 2.6% versus 51 +/- 2.7% (p < 0.01). Ginsenoside Rb1 preconditioning also markedly reduced the plasma CK, CK-MB, LDH and troponin T levels in blood. Akt phosphorylation expression increased after ginsenoside Rb1 preconditioning. These effects of ginsenoside Rb1 preconditioning were significantly inhibited by wortmannin. CONCLUSION: This is the first study to demonstrate that ginsenoside Rb1 preconditioning has protective effects on myocardial ischemia and reperfusion injury, partly by mediating the activation of the PI3K pathway and phosphorylation of Akt.