Effects of maslinic acid on cardiac function in ischemia–reperfusion injury rats

Maslinic acid (MA), a pentacyclic triterpenoid, has been reported to exert broad pharmacological properties. However, it is still unclear whether MA exhibits protective effects against ischemia/reperfusion (I/R) injury. Herein, we aimed to investigate the effects of MA on I/R injury and its underlying mechanisms. A rat model of I/R injury was established and administrated with MA by intraperitoneal injection. Cardiac function was assessed with a color ultrasound diagnosis system and PowerLab system. The levels of oxidative stress-related and I/R-related biomarkers were evaluated by using commercial kits. Apoptosis-related biomarkers and sirtuin (SIRT)1/AMP-activated protein kinase (AMPK) signaling proteins were determined by using quantitative reverse transcription PCR and western blotting, respectively. Treatment with MA improved cardiac performance and cardiac hemodynamic parameters in the I/R injury rat model. Besides, treatment with MA (20 mg/kg) ameliorated I/R injury-related biomarkers in serum. Interestingly, treatment with MA (20 mg/kg) also regulated myocardial apoptosis and inhibited oxidative-stress in left ventricular tissue. Mechanistic studies demonstrated that MA upregulated SIRT1 and AMPK phosphorylation in the left ventricular tissue. In summary, MA exerted protective effects against the impairments of cardiac function in I/R injury rats by the regulation of SIRT1/AMPK signaling pathways.

MicroRNA Expression Profile Changes after Cardiopulmonary Bypass and Ischemia/Reperfusion-Injury in a Porcine Model of Cardioplegic Arrest

Identification of microRNAs (miRNA) associated with cardiopulmonary bypass, cardiac arrest and subsequent myocardial ischemia/reperfusion may unravel novel therapeutic targets and biomarkers. The primary aim of the present study was to investigate the effects of cardiopulmonary bypass and temperature of cardioplegic arrest on myocardial miRNA profile in pigs’ left ventricular tissue. We employed next-generation sequencing to analyse miRNA profiles in the following groups: (1) hearts were arrested with antegrade warm St Thomas Hospital No. 2 (STH2) cardioplegia (n = 5; STH2-warm, 37 °C) and (2) cold STH2 (n = 6; STH2-cold, 4 °C) cardioplegia. Sixty min of ischemia was followed by 60 min of on-pump reperfusion with an additional 90 min of off-pump reperfusion. In addition, two groups without cardiac arrest (off-pump and on-pump group; n = 3, respectively) served as additional controls. STH2-warm and STH2-cold cardioplegia revealed no hemodynamic differences. In contrast, coronary venous creatine kinase-myocardial band (CK-MB) levels were significantly lower in pigs receiving STH2-warm cardioplegia (p < 0.05). Principal component analysis revealed that cardiopulmonary bypass and cardioplegic arrest markedly affected miRNAs in left ventricular tissue. Accordingly, ssc-miR-122, ssc-miR-10a-5p, ssc-miR-193a-3p, ssc-miR-499-3p, ssc-miR-374a-5p, ssc-miR-345-5p, ssc-miR-142-3p, ssc-miR-424-5p, ssc-miR-545-3p, ssc-miR-30b-5p, ssc-miR-145-5p, ssc-miR-374b-5p and ssc-miR-139-3p were differently regulated by cardiopulmonary bypass (false discovery rate (FDR) < 0.05 versus off-pump group). However, only ssc-miR-451 was differently expressed between STH2-warm and STH2-cold (FDR < 0.05). These data demonstrate for the first time that cardiopulmonary bypass and temperature of cardioplegic solution affected the expression of miRNAs in left ventricular tissue. In conclusion, specific miRNAs are potential therapeutic targets for limiting ischemia-reperfusion injury in patients undergoing cardiac surgery.

Blood pressure variability, heart functionality, and left ventricular tissue alterations in a protocol of severe hemorrhagic shock and resuscitation

Autonomic control of blood pressure (BP) and heart rate (HR) is crucial during bleeding and hemorrhagic shock (HS) to compensate for hypotension and hypoxia. Previous works have observed that at the point of hemodynamic decompensation a marked suppression of BP and HR variability occurs, leading to irreversible shock. We hypothesized that recovery of the autonomic control may be decisive for effective resuscitation, along with restoration of mean BP. We computed cardiovascular indexes of baroreflex sensitivity and BP and HR variability by analyzing hemodynamic recordings collected from five pigs during a protocol of severe hemorrhage and resuscitation; three pigs were sham-treated controls. Moreover, we assessed the effects of severe hemorrhage on heart functionality by integrating the hemodynamic findings with measures of plasma high-sensitivity cardiac troponin T and metabolite concentrations in left ventricular (LV) tissue. Resuscitation was performed with fluids and norepinephrine and then by reinfusion of shed blood. After first resuscitation, mean BP reached the target value, but cardiovascular indexes were not fully restored, hinting at a partial recovery of the autonomic mechanisms. Moreover, cardiac troponins were still elevated, suggesting a persistent myocardial sufferance. After blood reinfusion all the indexes returned to baseline. In the harvested heart, LV metabolic profile confirmed the acute stress condition sensed by the cardiomyocytes. Variability indexes and baroreflex trends can be valuable tools to evaluate the severity of HS, and they may represent a more useful end point for resuscitation in combination with standard measures such as mean values and biological measures. NEW & NOTEWORTHY Autonomic control of blood pressure was highly impaired during hemorrhagic shock, and it was not completely recovered after resuscitation despite global restoration of mean pressures. Moreover, a persistent myocardial sufferance emerged from measured cardiac troponin T and metabolite concentrations of left ventricular tissue. We highlight the importance of combining global mean values and biological markers with measures of variability and autonomic control for a better characterization of the effectiveness of the resuscitation strategy.

The Effects of Aqueous Extract from Nardostachys chinensis Batalin on Blood Pressure and Cardiac Hypertrophy in Two-Kidney One-Clip Hypertensive Rats

Aims. The aim of this study was to investigate the effects of the aqueous extract of Nardostachys chinensis Batalin (NCBAE) on blood pressure and cardiac hypertrophy using two-kidney one-clip (2K1C) hypertensive rats. Methods. 2K1C rat models were set up by clipping the left renal artery. Sham-operated rats underwent the same surgical procedure except for renal arterial clipping. 2K1C hypertensive rats were orally given NCBAE at doses of 210, 420, and 630 mg·kg−1·d−1 for 6 weeks. Twelve weeks after surgery, rat SBP and echocardiographic parameters were measured, cardiac histopathology was assessed, serum NO and LDH were detected, and the expression of Bcl-2 and caspase-3 of left ventricular tissue was assessed by western blot. Results. Treatment with NCBAE resulted in a decrease of SBP, LVPWd, LVPWs, IVSd, IVSs, LVW/BW ratio, and cardiomyocyte CSA, an increase of LVEF, and inhibition of 2K1C-induced reduction in serum NO and elevation of LDH compared with 2K1C group. NCBAE intervention also showed a significant increase of Bcl-2 expression and reduction of cleaved caspase-3 level dose-dependently in left ventricular tissue. Conclusion. Our data demonstrate that NCBAE has an antihypertensive property and protective effect on 2K1C-induced cardiac hypertrophy especially at the dose of 630 mg·kg−1·d−1.

Abstract 19706: CD39/CD73 Pathway in End-stage Human Ischemic Cardiomyopathy

Introduction: CD39 (ectonucleoside triphosphate diphosphohydrolase) is a nucleotidase expressed on endothelial cells, vascular smooth muscles cells, and leukocytes. CD39 plays a key role in vascular homeostasis, hydrolyzing extracellular ATP or ADP to AMP. CD73 (ecto-5’-nculeotidase) hydrolyzes AMP to adenosine. Both CD39 and CD73 are key modulators of purinergic signaling and have been shown to be important in ischemic preconditioning and ischemia reperfusion in animal models. Hypothesis: We hypothesized that the expression of the purine nucleotide-metabolizing pathway consisting of CD39 and CD73 in human hearts with ischemic cardiomyopathy is unregulated in response to ischemia. Methods: We compared the expression of CD39 and CD73 in left ventricular samples from patients with end-stage ischemic cardiomyopathy and normal hearts. Left ventricular tissue obtained from 7 end-stage ischemic cardiomyopathy hearts and 7 normal hearts not used for transplantation were homogenized and the levels of CD39 and CD73 mRNA were measured by qRT-PCR. Using the same tissue, immunoblot analysis for the protein level of CD39 and CD73 was conducted. Furthermore, immunohistochemical analysis of CD39 and CD73 expression was conducted on left ventricular tissue from the same subjects. Results: The total mRNA levels of CD39 and CD73 were increased in patients with end-stage ischemic cardiomyopathy. However, while there was a reduction in the total CD73 protein levels that did not reach significance, there was a marked reduction in the the total protein level of CD39 in ICM hearts (Figure). Immunohistochemical analysis demonstrated that the expression pattern of CD39 was significantly different in ICM hearts compared to normal hearts. Conclusions: These data provide important evidence that the extracellular nucleotide metabolizing pathway is altered in ICM. CD39 protein levels are significantly reduced in human end-stage ischemic cardiomyopathy.