Drugs mediating myocardial protection

Transcriptome, network analysis, and molecular docking approaches to elucidate the modes of action of Astragaloside IV against myocardial infarction with mitochondrial energy metabolism network-targeted regulation

BACKGROUND

Mitochondria play central role in cardiac energy metabolism modulations. Cardiac energy metabolism could be potential therapeutic target for the treatment of ischemic heart disease (IHD). We proposed strategy to analyze the regulation modes of astragaloside IV (AST) by targeting mitochondrial-energy-metabolism (MEM) in IHD based on transcriptome, network analysis, molecular docking (MD) and western blot (WB).

METHOD

IHD-associated genes and AST potential targets were collected from databases and references. MEM-related genes were obtained from MitoProteome. Cytoscape was applied to construct networks, present visualization, and conduct KEGG pathway enrichment. AST regulated energy-metabolism-associated-IHD-network (AEIN) was created, and reverse rates calculated from network analysis of transcriptome from rat myocardial infarction experiments were assigned to AEIN. Binding affinities and modes were evaluated by MD with further WB validation of targets expression.

RESULTS

The study identified 1713 IHD-related genes, 528 MEM-related genes, and 169 potential AST target genes. 21 AST targets were obtained from AEIN, while the top three targets Akt1, ERK1/2 and RPS6KB1 showed good binding affinities with AST (-10, -9.8, -8.6 and -8.8 kcal/mol for Akt1, Erk1, Erk2 and RPS6KB1 respectively). AST reversed the decreased expressions of three targets against OGD injury of H9c2. 13 MEM-associated signaling pathways, including HIF-1, and PI3K-Akt signaling pathways, were retrieved showing certain inter-relationships both in compositions and functions.

CONCLUSIONS

AST may have coordinated roles among multi-pathways in regulating MEM homeostasis in IHD. While further deep investigations should be designed and conducted to decipher and pinpoint the multi-target, multi-pathway modes of action of AST in the future.

New advances in perioperative cardioprotection

With the increasing age of the general population, medical conditions necessitating a surgical intervention will increase. Concomitant with advanced age, the prevalence of type 2 diabetes mellitus will also increase. These patients have a two- to three-fold higher risk of occurrence of cardiovascular events and are at higher risk of perioperative myocardial ischemia. This review will discuss recent advances in the field of perioperative cardioprotection and focus specifically on strategies that have aimed to protect the diabetic and the aged myocardium. This review will not deal with potential putative cardioprotective effects of opioids and anesthetic agents, as this is a very broad area that would necessitate a dedicated overview.

Sevoflurane anesthesia during acute right ventricular ischemia in pigs preserves cardiac function better than propofol anesthesia

BACKGROUND

The intention of the present study was to evaluate possible cardioprotective properties of inhalation anesthesia with sevoflurane.

METHODS AND MATERIALS

A porcine, open-chest model of right ventricular ischemia was used in 7 pigs receiving inhalation anesthesia with sevoflurane. The model was earlier developed and published by our group, using pigs receiving intravenous anesthesia with propofol. They served as controls. The animals were observed for three hours after the induction of right ventricular ischemia by ligation of the main branches supplying the right ventricular free wall.

RESULTS

In the sevoflurane group, the cardiac output recovered 2 hours after the induction of ischemia and intact right ventricular stroke work was observed. In the propofol group, no such recovery occurred. The release of troponin T was significantly lower than in the sevoflurane group.

CONCLUSIONS

Inhalation anesthesia with sevoflurane seems superior to intravenous anesthesia with propofol in acute right ventricular ischemic dysfunction.

Cardioprotection against myocardial reperfusion injury: successes, failures, and perspectives

The past few decades have witnessed an enormous number of research strategies aimed at protecting the heart against myocardial ischemia-reperfusion injury. Several randomized clinical trials are nowadays in progress testing whether promising therapeutic strategies aimed at preventing lethal reperfusion injury can be translated from bench to bedside. Many of these interventions, either pharmacological or mechanical, are targeting mitochondria as the final effectors of cardioprotection. Despite encouraging pre-clinical studies and small proof of concept clinical trials, there are still several limitations that may jeopardize the efficacy of cardioprotective strategies. These limitations include clinical setting, patient profile, drug administration, and methods for evaluating treatment efficacy. Identifying potential mechanistic and methodological pitfalls in the field may improve future translational research.

Diabetes, perioperative ischaemia and volatile anaesthetics: consequences of derangements in myocardial substrate metabolism

Volatile anaesthetics exert protective effects on the heart against perioperative ischaemic injury. However, there is growing evidence that these cardioprotective properties are reduced in case of type 2 diabetes mellitus. A strong predictor of postoperative cardiac function is myocardial substrate metabolism. In the type 2 diabetic heart, substrate metabolism is shifted from glucose utilisation to fatty acid oxidation, resulting in metabolic inflexibility and cardiac dysfunction. The ischaemic heart also loses its metabolic flexibility and can switch to glucose or fatty acid oxidation as its preferential state, which may deteriorate cardiac function even further in case of type 2 diabetes mellitus.Recent experimental studies suggest that the cardioprotective properties of volatile anaesthetics partly rely on changing myocardial substrate metabolism. Interventions that target at restoration of metabolic derangements, like lifestyle and pharmacological interventions, may therefore be an interesting candidate to reduce perioperative complications. This review will focus on the current knowledge regarding myocardial substrate metabolism during volatile anaesthesia in the obese and type 2 diabetic heart during perioperative ischaemia.

Ouabain--the key to cardioprotection?

Based on a wealth of mechanistic evidence supported by the fact that ouabain mimics the spleen-liver effect in this article, the hypothesis is established that the endogenous hormone ouabain not only mimics the effects of ischemic preconditioning but also may be an ideal drug for the prevention of ischemic diseases. Moreover, it is argued that the spleen-liver effect may represent a general protective mechanism for the protection of organisms against oxygen deficiency. Investigating the spleen-liver mechanism offers a new approach to decipher the secrets of ischemic conditioning. Preconditioning represents a basic mechanism to protect a wide variety of cells against stressful stimuli such as ischemia. The ability to undergo preconditioning is almost ubiquitous in tissues and is highly conserved across species. Reinvestigation of the "spleen-liver mechanism" will allow the study of metabolic inhibitors and hormone mimics that all could help to transform ischemic preconditioning into a cure of the epidemic ischemic heart disease. Ouabain mimics the effects of the spleen factor. Cardioprotection induced by ouabain is due to the activation of pathways that are also activated in ischemic preconditioning. Just like ischemic preconditioning, ouabain activates the reperfusion injury salvage kinase pathway. Activation of nuclear factor kappa B and other transcription factors contribute to the long lasting effects of ouabain. The endogenous hormone ouabain just like preconditioning offers multiorgan protection based on innate mechanisms, which warrants clinical investigation. Clinical studies with ouabain that correspond to current standards are warranted.

Preconditioning of brain slices against hypoxia induced injury by a Gynostemma pentaphyllum extract--stimulation of anti-oxidative enzyme expression

A short period of hypoxia/hypoglycaemia (oxygen and glucose deprivation, OGD) induced by perfusion with O(2)/glucose-free medium caused immediate loss and incomplete restoration of evoked field potentials in the CA1 region of transverse hippocampus slices. OGD-dependent decrease in evoked field potentials can be prevented by a proceeding short OGD event (preconditioning). We report about a study investigating the effect of an ethanolic Gynostemma pentaphyllum extract on evoked field potentials when administered before the OGD episode. Using this procedure, the extract completely protected the cells of the slices from functional injury. In an astroglia rich cell culture the ethanolic Gynostemma pentaphyllum extract caused within 48 h of cultivation increased protein and activity levels of the anti-oxidative enzymes manganese superoxide dismutase (Mn-SOD) and glutathione peroxidase (GPx). Consequently, the cellular H(2)O(2) concentration remained at a low level. These data suggest that the Gynostemma pentaphyllum-mediated increase in antioxidative enzyme activities may contribute to the protection of transverse hippocampus slices from OGD induced functional injury. Our results demonstrate that the prophylactic administration of the ethanolic extract from Gynostemma pentaphyllum has a high potential to protect from ischemia/reperfusion injury.

The influence of surgery on the onset of symptomatic coronary artery disease

We speculated that asymptomatic patients undergoing routine surgery might be at higher risk of subsequent cardiac events. We studied 183,534 patients with no prior admission for heart disease, aged 50-75 years, admitted electively for one of five operations considered medium to low risk of peri-operative cardiac morbidity, between January 1997 and December 2005. Controls were generated from linked records. Within 3 years 3444 (1.9%) patients undergoing operations had subsequent myocardial infarction/acute coronary syndrome (MI/ACS) compared with 3708 (2.0%) controls (p < 0.001). Overall 8406 (4.6%) patients undergoing surgery had MI/ACS compared with 9306 (5.1%) controls (p < 0.001). Of patients undergoing surgery, 20.2% died compared with 25.7% of controls (p < 0.001). Patients undergoing certain surgical procedures did not have a higher incidence of readmission for cardiac events, but had a general survival benefit compared with other elective hospital admissions. Assessment for surgery may represent a health benefit beyond the original surgery.