Effect of microRNA-208a on mitochondrial apoptosis of cardiomyocytes of neonatal rats.

OBJECTIVE: To explore the effect and mechanism of microRNA-208a (miR-208a) in the mitochondrial apoptosis of cardiomyocytes of neonatal rats. METHODS: The primary cultured cardiomyocytes of neonatal rats were added into the hypoxia incubator for the hypoxia induction. The overexpression system for miR-208a of cardiomyocytes of neonatal rats was built. The flow cytometry assay was employed to detect the incidence of apoptosis in the over-expressed miR-208a. The mitochondrial staining technique was used to detect the change in the mitochondrial morphology of over-expressed miR-208a. The bioinformatic analysis was chosen to analyze and predict the target gene of miR-208a. RESULTS: Firstly, the primary culture system of cardiomyocytes of neonatal rats was successfully built. The miR-208a was over-expressed in cardiomyocytes of neonatal rats by miR-208a Mimics. Results of flow cytometry assay showed that the over-expressed miR-208a could significantly reduce the incidence of apoptosis; while results of mitochondrial staining indicated the change in the mitochondrial morphology of over-expressed miR-208a and the mitochondrial fission process was inhibited. In conclusion, it was supposed that miR-208a could inhibit the activation of mitochondrial fission process to keep the cardiomyocytes from apoptosis. CONCLUSIONS: The over-expressed miR-208a can reduce the incidence of apoptosis in the cardiomyocytes of neonatal rats, significantly change the mitochondrial morphology and inhibit the mitochondrial fission process.

Coronary Revascularization Improves QT Dispersion in Patients with Chronic Coronary Artery Total Occlusion.

As an important parameter of cardiac functions, QT interval is usually irregular in patients with chronic coronary artery total occlusion (CTO). We sought to determine the effect of coronary revascularization (CRV) on QT interval dispersion in patients with CTO. To this end, we used electrocardiogram of 12 leads to record changes in the QT interval dispersion in 22 patients with CTO treated with percutaneous coronary intervention (PCI) and 24 patients treated with coronary artery bypass grafting (CABG). Our data showed that QTd and QTcd diminished markedly (P < 0.01) after PCI or CABG. No significant difference was observed between the postoperative groups (P > 0.05) or between PCI and CABG groups. We concluded that CRV could diminish QTd and QTcd in patients with CTO with no distinguishable differences with PCI and CABG procedures. Therefore, CRV can revitalize the existing functional myocardium and resume the myocardial electrophysiological functions in patients with CTO.

Analysis of heart rate variability in masked hypertension.

To investigate heart rate variability (HRV) in patients with masked hypertension (MH), participants were classified based on clinic and 24-h ambulatory blood-pressure monitoring: essential hypertension (EH, n = 40; MH, n = 36) and normotension (NT, n = 48). The HRV parameters were observed using a 24-h Holter monitor. Compared with NT controls, the parameters of HRV (SDNN, SDANN, SDNN Index, RMSSD, HF) and parameters in EH and MH patients had significantly decreased. No statistically significant difference in the HRV parameters was found between the EH and MH groups. The changes in HRV parameters show cardiac autonomic nerve dysfunction in patients with MH.

Assessment of recanalization of chronic total occlusions on left ventricular function in patients with or without previous myocardial infarction by real-time three-dimensional echocardiography.

The changes of left ventricular ejection fraction (LVEF) were assessed after successful recanalization of chronic total occlusions (CTO) with or without previous myocardial infarction (MI) by real-time three-dimensional echocardiography (RT3DE). 32 patients with a successfully recanalyzed CTO were included in the present prospective study. The patients were divided into group 1 without previous MI and group 2 with previous MI in the territories of total occlusion vessel that was recanalized. In addition, there was a subgroup composed of 14 patients with collateral flow or retrograde flow in group 2. In all patients, LVEF was determined by RT3DE at baseline and after 6 weeks. In group 1, the evolution of LVEF increased significantly from 59.9 ± 7.2-67.5 ± 8.7% (P < 0.05). In group 2, the evolution of LVEF increased from 48.6 ± 6.1-50.1 ± 6.4%, however, it was without statistic significance (P > 0.05). The evolution of LVEF increased from 46.8 ± 7.1-53.0 ± 7.2% (P < 0.05) in the subgroup of group 2. Left ventricular function in patients with CTO can be feasibility and actually evaluated by RT3DE. The influence of recanalization of CTO on the improvement of left ventricular function was different between MI and non-MI patients. The left ventricular function did not improve in MI patients, but improved significantly in the patients having rich collateral circulation.