Remifentanil preconditioning confers delayed cardioprotection in the rat †

Remifentanil protects against myocardial ischemia/reperfusion injury via miR-205-mediated regulation of PINK1

Myocardial ischemia/reperfusion (I/R) injury could lead to severe cardiovascular ischemic disease, including myocardial infarction and contractile dysfunction. Remifentanil demonstrated protective effect on myocardial I/R injury. The underlying pathophysiological mechanism was then investigated in this study. In the current study, primary cardiomyocytes were isolated from rats, and then preconditioned with remifentanil. Rats, tail vein injected with miR-205 antagomir, were subjected to infusion of remifentanil, and then subjected to regional ischemia followed by reperfusion. The results demonstrated that cell viability of hypoxia/reoxygenation-induced cardiomyocytes was increased post remifentanil, while the apoptosis was decreased accompanied with reduced cleaved caspase-3 expression. Hypoxia/reoxygenation treatment increased miR-205 and decreased PINK1 (PTEN induced putative kinase 1) expression. However, preconditioning with remifentanil reduced miR-205 and enhanced PINK1. Moreover, over-expression of miR-205 decreased PINK1 expression and counteracted the effects of remifentanil-induced increase of cell viability and decrease of cell apoptosis in hypoxia/reoxygenation-induced cardiomyocytes. Injection with miR-205 antagomir improved remifentanil-induced decrease of infarct size and LDH (lactic acid dehydrogenase) activity in rat model with I/R injury. In conclusion, miR-205 might participate in the protective effect of remifentanil in rat myocardial I/R injury via regulation of PINK1, providing a potential target for amelioration of cardiovascular ischemic disease.

Inhibited histone deacetylase 3 ameliorates myocardial ischemia-reperfusion injury in a rat model by elevating microRNA-19a-3p and reducing cyclin-dependent kinase 2

OBJECTIVE

Over the years, the roles of microRNAs (miRNAs) and histone deacetylase 3 (HDAC3) in human diseases have been investigated. This study focused on the effect of miR-19a-3p and HDAC3 in myocardial ischemia-reperfusion (I/R) injury (MIRI) by targeting cyclin-dependent kinase 2 (CDK2).

METHODS

The I/R rat models were established by coronary artery ligation, which were then treated with RGFP966 (an inhibitor of HDAC3), miR-19a-3p agomir or antagomir, or silenced CDK2 to explore their roles in the cardiac function, pathological changes of myocardial tissues, myocardial infarction area, inflammatory factors and oxidative stress factors in rats with MIRI. The expression of miR-19a-3p, HDAC3, and CDK2 was determined by RT-qPCR and western blot assay, and the interaction among which was also verified by online prediction, luciferase activity assay and ChIP assay.

RESULTS

The results indicated that HDAC3 and CDK2 were upregulated while miR-19a-3p was downregulated in myocardial tissues of I/R rats. The inhibited HDAC3/CDK2 or elevated miR-19a-3p could promote cardiac function, attenuate pathological changes, inflammatory reaction, oxidative stress, myocardial infarction area and apoptosis of myocardial tissues. HDAC3 mediates miR-19a-3p and CDK2 is targeted by miR-19a-3p.

CONCLUSION

Inhibited HDAC3 ameliorates MIRI in a rat model by elevating miR-19a-3p and reducing CDK2, which may contribute to the treatment of MIRI.

Remifentanil preconditioning protects against hypoxia-induced senescence and necroptosis in human cardiac myocytes in vitro

Remifentanil and other opioids are suggested to be protective against ischemia-reperfusion injury in animal models and coronary artery bypass surgery patients, however the molecular basis of such protection is far from being understood. In the present study, we have used a model of human cardiomyocytes treated with the hypoxia-mimetic agent cobalt chloride to investigate remifentanil preconditioning-based adaptive responses and underlying mechanisms. Hypoxic conditions promoted oxidative and nitrosative stress, p21-mediated cellular senescence and the activation of necroptotic pathway that was accompanied by a 2.2-, 9.6- and 8.2-fold increase in phosphorylation status of mixed lineage kinase domain-like pseudokinase (MLKL) and release of pro-inflammatory cytokine IL-8 and cardiac troponin I, a marker of myocardial damage, respectively. Remifentanil preconditioning was able to lower hypoxia-mediated protein carbonylation and limit MLKL-based signaling and pro-inflammatory response to almost normoxic control levels, and decrease hypoxia-induced pro-senescent activity of about 21% compared to control hypoxic conditions. In summary, we have shown for the first time that remifentanil can protect human cardiomyocytes against hypoxia-induced cellular senescence and necroptosis that may have importance with respect to the use of remifentanil to diminish myocardial ischemia and reperfusion injury in patients undergoing cardiac surgery.

Remifentanil Induces Cardio Protection Against Ischemia/Reperfusion Injury by Inhibiting Endoplasmic Reticulum Stress Through the Maintenance of Zinc Homeostasis

BACKGROUND

Although it is well known that remifentanil (Rem) elicits cardiac protection against ischemia/reperfusion (I/R) injury, the underlying mechanism remains unclear. This study tested if Rem can protect the heart from I/R injury by inhibiting endoplasmic reticulum (ER) stress through the maintenance of zinc (Zn) homeostasis.

METHODS

Isolated rat hearts were subjected to 30 minutes of regional ischemia followed by 2 hours of reperfusion. Rem was given by 3 consecutive 5-minute infusions, and each infusion was followed by a 5-minute drug-free perfusion before ischemia. Total Zn concentrations in cardiac tissue, cardiac function, infarct size, and apoptosis were assessed. H9c2 cells were subjected to 6 hours of hypoxia and 2 hours of reoxygenation (hypoxia/reoxygenation [H/R]), and Rem was given for 30 minutes before hypoxia. Metal-responsive transcription factor 1 (MTF1) overexpression plasmids were transfected into H9c2 cells 48 hours before hypoxia. Intracellular Zn level, cell viability, and mitochondrial injury parameters were evaluated. A Zn chelator N,N,N',N'-tetrakis-(2-pyridylmethyl) ethylenediamine (TPEN) or an ER stress activator thapsigargin was administrated during in vitro and ex vivo studies. The regulatory molecules related to Zn homeostasis and ER stress in cardiac tissue, and cardiomyocytes were analyzed by Western blotting.

RESULTS

Rem caused significant reversion of Zn loss from the heart (Rem + I/R versus I/R, 9.43 ± 0.55 vs 7.53 ± 1.18; P < .05) by suppressing the expression of MTF1 and Zn transporter 1 (ZnT1). The inhibited expression of ER stress markers after Rem preconditioning was abolished by TPEN. Rem preconditioning improved the cardiac function accompanied by the reduction of infarct size (Rem + I/R versus I/R, 21% ± 4% vs 40% ± 6%; P < .05). The protective effects of Rem could be reserved by TPEN and thapsigargin. Similar effects were observed in H9c2 cells exposed to H/R. In addition, MTF1 overexpression blocked the inhibitory effects of Rem on ZnT1 expression and ER stress at reoxygenation. Rem attenuated the collapse of mitochondrial membrane potential (ΔΨm) and the generation of mitochondrial reactive oxygen species by inhibiting ER stress via cardiac Zn restoration (Rem + H/R versus H/R, 79.57% ± 10.62% vs 58.27% ± 4.32%; P < .05).

CONCLUSIONS

Rem maintains Zn homeostasis at reperfusion by inhibiting MTF1 and ZnT1 expression, leading to the attenuation of ER stress and cardiac injury. Our findings provide a promising therapeutic approach for managing acute myocardial I/R injury.

Hypercholesterolemia Abrogates Remote Ischemic Preconditioning-Induced Cardioprotection: Role of Reperfusion Injury Salvage Kinase Signals

Remote ischemic preconditioning (RIPC) is one of the most powerful intrinsic cardioprotective strategies discovered so far and experimental data indicate that comorbidity may interfere with the protection by RIPC. Therefore, we investigate whether RIPC-induced cardioprotection was intact in hypercholesterolemic rat hearts exposed to ischemia reperfusion in vivo. Normal or hypercholesterolemic rat hearts were exposed to 30 min of ischemia and 2 h of reperfusion, with or without RIPC, PI3K inhibitor wortmannin, MEK-ERK1/2 inhibitor PD98059, GSK3β inhibitor SB216763. Infarct size, apoptosis, MG53, PI3K-p85, p-Akt, p-ERK1/2, p-GSK3β, and cleaved Caspase-3 were determined. RIPC reduced infarct size, limited cardiomyocyte apoptosis following IR that was blocked by wortmannin but not PD98059. RIPC triggered unique cardioprotective signaling including MG53, phosphorylation of Akt, and glycogen synthase kinase-3ß (GSK3β) in concert with reduced proapoptotic active caspase-3. In contrast, RIPC failed to reduce myocardial necrosis and apoptosis as well as to increase the phosphorylated Akt and GSK3β in hypercholestorolemic myocardium. Importantly, we found that inhibition of GSK with SB216763 reduced myocardial infarct size in healthy and hypercholesterolemic hearts, but no additional cardioprotective effect was achieved when combined with RIPC. Our results suggest that acute GSK3β inhibition may provide a novel therapeutic strategy for hypercholesterolemic patients during acute myocardial infarction, whereas RIPC is less effective due to signaling events that adversely affect GSK3β.

Prospects for Creation of Cardioprotective and Antiarrhythmic Drugs Based on Opioid Receptor Agonists

It has now been demonstrated that the μ, δ1 , δ2 , and κ1 opioid receptor (OR) agonists represent the most promising group of opioids for the creation of drugs enhancing cardiac tolerance to the detrimental effects of ischemia/reperfusion (I/R). Opioids are able to prevent necrosis and apoptosis of cardiomyocytes during I/R and improve cardiac contractility in the reperfusion period. The OR agonists exert an infarct-reducing effect with prophylactic administration and prevent reperfusion-induced cardiomyocyte death when ischemic injury of heart has already occurred; that is, opioids can mimic preconditioning and postconditioning phenomena. Furthermore, opioids are also effective in preventing ischemia-induced arrhythmias.

Peri-operative cardiac protection for non-cardiac surgery

Cardiovascular complications are an important cause of morbidity and mortality after non-cardiac surgery. Pre-operative identification of high-risk individuals and appropriate peri-operative management can reduce cardiovascular risk. It is important to continue chronic beta-blocker and statin therapy. Statins are relatively safe and peri-operative initiation may be beneficial in high-risk patients and those scheduled for vascular surgery. The pre-operative introduction of beta-blockers reduces myocardial injury but increases rates of stroke and mortality, possibly due to hypotension. They should only be considered in high-risk patients and the dose should be titrated to heart rate. Alpha-2 agonists may also contribute to hypotension. Aspirin continuation can increase the risk of major bleeding and offset the benefit of reduced myocardial risk. Contrary to the initial ENIGMA study, nitrous oxide does not seem to increase the risk of myocardial injury. Volatile anaesthetic agents and opioids have been shown to be cardioprotective in animal laboratory studies but these effects have, so far, not been conclusively reproduced clinically.

Remifentanil preconditioning protects the small intestine against ischemia/reperfusion injury via intestinal δ- and μ-opioid receptors

BACKGROUND

Intestinal ischemia/reperfusion (I/R) injury can cause a high rate of mortality in the perioperative period. Remifentanil has been reported to provide protection for organs against I/R injury. We hypothesized that remifentanil preconditioning would attenuate the small intestinal injury induced by intestinal I/R.

METHODS

We used both an in vivo rat model of intestinal I/R injury and a cell culture model using IEC-6 cells (the rat intestinal epithelial cell line) subjected to oxygen and glucose deprivation (OGD). Remifentanil was administered before ischemia or OGD, and 3 specific opioid receptors antagonists, naltrindole (a δ-OR selective antagonist), nor-binaltorphimine (nor-BNI, a κ-OR selective antagonist), and CTOP (a μ-OR selective antagonist), were administered before preconditioning to determine the role of opioid receptors in the intestinal protection mediated by remifentanil.

RESULTS

In the in vivo rat model, intestinal I/R induced obvious intestinal injury as evidenced by increases in the Chiu score, serum diamine oxidase activity, the apoptosis index, and the level of cleaved caspase-3 protein expression, whereas remifentanil preconditioning significantly improved these changes in vivo. In the in vitro cell culture exposed to OGD, cell viability (MTT, ie, (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay and flow cytometric analysis showed that remifentanil preconditioning enhanced IEC-6 cell viability and decreased apoptosis. In both in vitro and in vivo models, the aforementioned protective effects of remifentanil preconditioning were abolished completely by previous administration of the δ- or μ-opioid markedly attentuated but not the κ-opioid receptor antagonist.

CONCLUSION

Remifentanil preconditioning appears to act via δ- and μ-opioid receptors to protect the small intestine from intestinal I/R injury by attenuating apoptosis of the intestinal mucosal epithelial cells.

Effects of Remifentanil Preconditioning on Osteoblasts under Hypoxia-Reoxygenation Condition

BACKGROUND

Ischemia-reperfusion of bone occurs in a variety of clinical conditions, such as orthopedic arthroplasty, plastic gnathoplasty, spinal surgery, and amputation. Usually, cellular models of hypoxia-reoxygenation reflect in vivo models of ischemia-reperfusion. With respect to hypoxia-reoxygenation conditions, the effects of remifentanil on osteogenesis have received little attention. Therefore, we investigated the effects of remifentanil on the proliferation and differentiation of osteoblasts during hypoxic-reoxygenation.

METHODS

After remifentanil (0.1, 1 ng/mL) preconditioning for 2 hours, human osteoblasts were cultured under 1% oxygen tension for 24 hours. Thereafter, the cells were reoxygenated for 12 hours at 37 °C. The naloxone groups were treated with naloxone for 30 minutes before remifentanil treatment. We measured cell viability via MTT assay. Osteoblast maturation was determined by assay of bone nodular mineralization. Quantitative PCR and western blot methods were used to determine BMP-2, osteocalcin, Akt, type I collagen, osterix, TGF-β1, HIF-1α, and RUNX2 expression levels.

RESULTS

Osteoblast viability and bone nodular mineralization by osteoblasts is recovered by remifentanil preconditioning from hypoxia-reoxygenation insult. During hypoxic-reoxygenation condition, remifentanil preconditioning induced the expression of BMP-2, osteocalcin, Akt, type I collagen, osterix, TGF-β1, HIF-1α, and RUNX2 in osteoblasts.

CONCLUSIONS

Under hypoxia-reoxygenation conditions, remifentanil preconditioning enhanced the cell viability and maturation of osteoblasts, and stimulated the expression of proteins associated with osteoblast proliferation and differentiation of the osteoblast. Our results suggest that remifentanil may help in the treatment of bone stress injuries.

Effect of aortic root infusion of sufentanil on ischemia-reperfusion injury in patients undergoing mitral valve replacement

OBJECTIVE

This study investigated the effects of aortic root infusion of sufentanil on myocardial ischemia/reperfusion injury in patients undergoing elective mitral valve replacement (MVR) with cardiopulmonary bypass (CPB).

DESIGN

A prospective, randomized, clinical study.

SETTING

A university-affiliated teaching hospital.

PARTICIPANTS

Fifty-three adult patients undergoing elective MVR with CPB.

INTERVENTIONS

Bolus infusions of sufentanil (0.2 μg/kg, n = 24) or normal saline (n = 29) were administered through the aortic root cardioplegia perfusion catheter 5 minutes before aortic unclamping.

MEASUREMENTS AND MAIN RESULTS

Plasma concentrations of CK-MB and cTnI and variables including heart rate, mean arterial pressure, central venous pressure, cardiac output, stroke volume, duration of mechanical ventilation, length of ICU stay, length of hospital stay, and 24-hour postoperative inotropic scores were recorded. Plasma concentrations of CK-MB and cTnI were significantly lower 4 and 8 hours after aortic unclamping in the sufentanil postconditioning group compared to control (p<0.05). Inotropic drug use, duration of mechanical ventilation, and length of ICU and hospital stays were reduced significantly in the sufentanil postconditioning group compared to control (p< 0.05).

CONCLUSIONS

The present study demonstrated that sufentanil can attenuate myocardial ischemia-reperfusion injury in patients undergoing elective MVR with CPB.

The anesthesia in abdominal aortic surgery (ABSENT) study: a prospective, randomized, controlled trial comparing troponin T release with fentanyl-sevoflurane and propofol-remifentanil anesthesia in major vascular surgery

BACKGROUND

On the basis of data indicating that volatile anesthetics induce cardioprotection in cardiac surgery, current guidelines recommend volatile anesthetics for maintenance of general anesthesia during noncardiac surgery in hemodynamic stable patients at risk for perioperative myocardial ischemia. The aim of the current study was to compare increased troponin T (TnT) values in patients receiving sevoflurane-based anesthesia or total intravenous anesthesia in elective abdominal aortic surgery.

METHODS

A prospective, randomized, open, parallel-group trial comparing sevoflurane-based anesthesia (group S) and total intravenous anesthesia (group T) with regard to cardioprotection in 193 patients scheduled for elective abdominal aortic surgery. Increased TnT level on the first postoperative day was the primary endpoint. Secondary endpoints were postoperative complications, nonfatal coronary events and mortality.

RESULTS

On the first postoperative day increased TnT values (>13 ng/l) were found in 43 (44%) patients in group S versus 41 (43%) in group T (P = 0.999), with no significant differences in TnT levels between the groups at any time point. Although underpowered, the authors found no differences in postoperative complications, nonfatal coronary events or mortality between the groups.

CONCLUSIONS

In elective abdominal aortic surgery sevoflurane-based anesthesia did not reduce myocardial injury, evaluated by TnT release, compared with total intravenous anesthesia. These data indicate that potential cardioprotective effects of volatile anesthetics found in cardiac surgery are less obvious in major vascular surgery.

Hypercholesterolemic myocardium is vulnerable to ischemia-reperfusion injury and refractory to sevoflurane-induced protection

Recent studies have demonstrated that volatile anesthetic postconditioning confers myocardial protection against ischemia-reperfusion (IR) injury through activation of the reperfusion injury salvage kinase (RISK) pathway. As RISK has been shown to be impaired in hypercholesterolemia. Therefore, we investigate whether anesthetic-induced cardiac protection was maintained in hypercholesterolemic rats. In the present study, normocholesteolemic or hypercholesterolemic rat hearts were subjected to 30 min of ischemia and 2 h of reperfusion. Animals received 2.4% sevoflurane for 5 min or 3 cycles of 10-s ischemia/10-s reperfusion. The hemodynamic parameters, including left ventricular developed pressure, left ventricular end-diastolic pressure and heart rate, were continuously monitored. The infarct size, apoptosis, p-Akt, p-ERK1/2, p-GSK3β were determined. We found that both sevoflurane and ischemic postconditioning significantly improved heart pump function, reduced infarct size and increased the phosphorylation of Akt, ERK1/2 and their downstream target of GSK3β in the healthy rats. In the hypercholesterolemic rats, neither sevoflurane nor ischemic postconditioning improved left ventricular hemodynamics, reduced infarct size and increased the phosphorylated Akt, ERK1/2 and GSK3β. In contrast, GSK inhibitor SB216763 conferred cardioprotection against IR injury in healthy and hypercholesterolemic hearts. In conclusions, hyperchoesterolemia abrogated sevoflurane-induced cardioprotection against IR injury by alteration of upstream signaling of GSK3β and acute GSK inhibition may provide a novel therapeutic strategy to protect hypercholesterolemic hearts against IR injury.

Atorvastatin-induced cardioprotection of human myocardium is mediated by the inhibition of mitochondrial permeability transition pore opening via tumor necrosis factor-α and Janus kinase/signal transducers and activators of transcription pathway

BACKGROUND

The role of tumor necrosis factor-α (TNF-α), Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway, and mitochondrial Permeability Transition Pore in atorvastatin-induced cardioprotection were examined in human myocardium, in vitro.

METHODS

Isometric force of contraction of human right atrial trabeculae was recorded during 30-min hypoxia and 60-min reoxygenation (control) and in the presence of atorvastatin (0.1 µM, 1 µM, 10 µM). In early reoxygenation, the TNF-α inhibitor, AG490 (inhibitor of JAK/STAT), or atractyloside (mitochondrial Permeability Transition Pore opener), were administered. Cyclosporine A (inhibitor of mitochondrial Permeability Transition Pore opening) was administered during the first minute of reoxygenation alone or in presence of atorvastatin and TNF-α inhibitor or AG490. The force of contraction (percentage of baseline) at the end of reoxygenation period was compared (mean ± SD; n = 6 in each group). Protein expression of JAK/STAT pathway was measured using Western immunoblotting.

RESULTS

Atorvastatin 0.1 µM (70 ± 9%), 1 µM (85 ± 5%), 10 µM (89 ± 5%), and Cyclosporine A (87 ± 10%) improved the recovery of force of contraction at the end of reoxygenation, as compared with control (50 ± 3%). Atorvastatin 1 µM (4.64 ± 2.90 ng · ml(-1) · g(-1) of tissue) decreased the release of troponin Ic after hypoxia-reoxygenation (control: 26.34 ± 19.30 ng · ml(-1) · g(-1); P < 0.001). The enhanced recovery of force of contraction after atorvastatin administration was abolished by TNF-α inhibitor (53 ± 8%), AG490 (56 ± 7%), atractyloside (48 ± 8%). Cyclosporine A restored the atorvastatin-induced cardioprotection abolished by TNF-α inhibitor (87 ± 6%) and AG490 (83 ± 9%). Atorvastatin significantly increased the phosphorylation of JAK-2 and STAT-3, TNF-α inhibitor abolished the enhanced phosphorylation of JAK-2 and STAT-3 by atorvastatin.

CONCLUSIONS

Atorvastatin-induced cardioprotection involved the inhibition of the mitochondrial Permeability Transition Pore opening via the activation of TNF-α and the JAK/STAT pathway in early reoxygenation.

Hypercholesterolemia blocked sevoflurane-induced cardioprotection against ischemia-reperfusion injury by alteration of the MG53/RISK/GSK3β signaling

BACKGROUND

Recent studies have demonstrated that volatile anesthetic preconditioning confers myocardial protection against ischemia-reperfusion (IR) injury through activation of the reperfusion injury salvage kinase (RISK) pathway. As RISK has been shown to be impaired in hypercholesterolemia, we investigate whether anesthetic-induced cardiac protection was maintained in hypercholesterolemic rats.

METHODS

Normocholesteolemic or hypercholesterolemic rat hearts were subjected to 30 min of ischemia and 2 h of reperfusion. Animals received 2.4% sevoflurane during three 5 min periods with and without PI3K antagonist wortmannin (10 μg/kg, Wort) or the ERK inhibitor PD 98059 (1 mg/kg, PD). The infarct size, apoptosis, p-Akt, p-ERK1/2, p-GSK3β were determined.

RESULTS

Two hundred and six rats were analyzed in the study. In the healthy rats, sevoflurane significantly reduced infarct size by 42%, a phenomenon completely reversed by wortmannin and PD98059 and increased the phosphorylation of Akt, ERK1/2 and their downstream target of GSK3β. In the hypercholesterolemic rats, sevoflurane failed to reduce infarct size and increase the phosphorylated Akt, ERK1/2 and GSK3β. In contrast, GSK inhibitor SB216763 conferred cardioprotection against IR injury in healthy and hypercholesterolemic hearts.

CONCLUSIONS

Hyperchoesterolemia abrogated sevoflurane-induced cardioprotection against IR injury by alteration of upstream signaling of GSK3β and acute GSK inhibition may provide a novel therapeutic strategy to protect hypercholesterolemic hearts against IR injury.

Sufentanil limits the myocardial infarct size by preservation of the phosphorylated connexin 43

Sufentanil, with a potent analgesia effect, has been wildly used in anesthesia and analgesia, especially for the cardiovascular surgeries. The aim of the study was to evaluate whether sufentanil provides cardioprotection and the effect of connexin 43 on the cardiac infarct size reduction. Sufentanil post-conditioning (bolus injection at 0.1, 0.3, 1, 3, 10 μg/kg) or ischemic post-conditioning (3 cycles of a 10s reperfusion alternating with a 10s ischemia) was induced in an intact rat heart model of ischemia-reperfusion injury. Both ischemic and sufentanil post-conditioning reduced the myocardial infarct size compared with control group. The infarct size limitation of sufentanil was dose-dependent, 1 μg/kg has the optimal effect and increasing dosage could not afford further cardioprotection. Connexin 43 underwent dephosphorylation in response to ischemia-reperfusion measured by Western blot at the anterior myocardium tissues of left ventricle while sufentanil preserved the phosphorylation of connexin 43. The results demonstrated that sufentanil limits myocardial infarct size which is similar with ischemic post-conditioning at the dosage of 1 μg/kg. Preservation of phosphorylation of connexin 43 plays an important role in the cardioprotection of ischemic and sufentanil post-conditioning.

Clinical application of the cardioprotective effects of volatile anaesthetics: CON--total intravenous anaesthesia or not total intravenous anaesthesia to anaesthetise a cardiac patient?

Although volatile anaesthetics show strong and easily reproducible cardioprotective effects in animal experiments, these effects are less obvious in clinical settings. Indeed, more than a decade after the first human clinical study, the number of publications has increased extensively, but the encouraging results from previous studies in terms of myocardial protection have failed to translate into an improvement in survival or a decrease the incidence of myocardial infarction. No consensus on the modalities of administration of volatile anaesthetics has been agreed and when the experimental protocols are transposed into daily clinical practice, their cardioprotective effects are still weak. The reasons for the disparities between experimental and clinical studies will be reviewed here, especially the role of patients' co-morbidities and medications as well as the limitations of the main positive clinical trials. Recent data showing anti-inflammatory properties of propofol will also be explained. One of the most important clinical benefits of propofol is that it can be used by target-controlled or continuous infusion for anaesthesia and sedation throughout the surgical and critical care periods without the risk of a transition failure. Further large multi-centre clinical investigations are still required.

Morphine and remifentanil-induced cardioprotection: its experimental and clinical outcomes

During the past few decades, a large number of animal studies demonstrated that commonly used opioids could provide cardioprotection against ischemia-reperfusion (I/R) injury. Opioid-induced preconditioning or postconditioning mimics ischemic preconditioning (I-Pre) or ischemic postconditioning (I-Post). Both δ- and κ-opioid receptors (OPRs) play a crucial role in opioid-induced cardioprotection (OIC). Down stream signaling effectors of OIC include ATP-sensitive potassium (K_ATP) channels, protein kinase C (PKC), tyrosine kinase, phosphatidylinositol-3-kinase (PI3-kinase), extracellular signal regulated kinase1/2 (ERK1/2), glycogen synthase kinase-3β (GSK-3β), and mitochondrial permeability transition pore (MPTP), among others. Recently, various reports also suggest that opioids could provide cardioprotection in humans. This review will discuss OIC using mostly morphine and remifentanil which are widely used during cardiac anesthesia in addition to the clinical implications of OIC.

Continuous administration of remifentanil and sufentanil induces cardioprotection in human myocardium, in vitro

BACKGROUND

Remifentanil and sufentanil are widely used opioids during general anaesthesia for cardiac and non-cardiac surgery. This study was conducted to evaluate the hypothesis that the continuous administration of remifentanil and sufentanil, at clinically relevant concentrations, could provide protection of human myocardium, in vitro, against hypoxia-reoxygenation injury.

METHOD

Isometrically contracting isolated human right atrial trabeculae were exposed to 30 min of hypoxia and 60 min of reoxygenation. In separate groups, remifentanil at 10(-11), 10(-10), 10(-9), or sufentanil at 10(-11), 10(-10), 10(-9) M were administered 10 min before hypoxia until the end of the experiment. The force of contraction (FoC) of trabeculae was recorded continuously. Developed force was compared (mean ± standard deviation) between the groups using a variance analysis and post hoc tests.

RESULTS

At the end of the 60-min reoxygenation, remifentanil 10(-11) M (FoC: 82 ± 7% of baseline), 10(-10) M (FoC: 78 ± 5% of baseline), 10(-9) M (FoC: 80 ± 4% of baseline) and sufentanil 10(-11) M (FoC: 78 ± 8% of baseline), 10(-10) M (FoC: 83 ± 6% of baseline), 10(-9) M (FoC: 83 ± 8% of baseline) enhanced the recovery of FoC as compared with the control group (53 ± 9% of baseline, P<0.0001).

CONCLUSIONS

Remifentanil and sufentanil, at clinically relevant concentrations, confer cardioprotection of human myocardium against hypoxia reoxygenation, in vitro.

Myocardial Injury in Remifentanil-Based Anaesthesia for off-Pump Coronary Artery Bypass Surgery: An Equipotent Dose of Sevoflurane versus Propofol

This randomised controlled trial compared the effect of equipotent anaesthetic doses of sevoflurane (S group) versus propofol (P group), during remifentanil-based anaesthesia for off-pump coronary artery bypass surgery, on myocardial injury. Either sevoflurane or propofol was titrated to maintain bispectral index values between 40 and 50. In both groups, a targeted concentration of remifentanil 20 ng.ml-1 was maintained during anaesthesia. The concentrations of creatine kinase MB and troponin I were measured before the start of surgery, on admission to the intensive care unit, and at 12 and 24 hours after intensive care unit admission. The postoperative values of creatine kinase MB (S group: 15.08±18.97, 20.78±20.92, 12.76±12.82 vs 2.09±1.54 ng.ml-1; P group: 10.99±13.15, 27.16±56.55, 11.88±18.80 vs 1.84±1.67 ng.ml-1) and troponin I (S group: 3.56±5.19, 5.66±7.89, 3.35±4.55 vs 0.52±1.90 ng.ml-1; P group: 2.42±3.33, 4.11±6.01, 3.04±5.31 vs 0.43±1.28 ng.ml-1) were significantly higher than preoperative values in both groups but there were no significant differences between the two groups. There were no significant differences in time to extubation (S group, 476±284 minutes; P group, 450±268 minutes) and intensive care unit length of stay (S group, 2775±1449 minutes; P group, 2797±1534 minutes) between the two groups. In conclusion, sevoflurane and propofol at equipotent doses guided by bispectral index with remifentanil 20 ng.ml-1 had similar creatine kinase MB and troponin I values.

Hyperglycemia attenuates myocardial preconditioning of remifentanil

BACKGROUND

Hyperglycemia attenuates cardioprotection by remifentanil-preconditioning in ischemia-reperfusion in vivo in diabetic rats. However, the effects of hyperglycemia in cultured ventricular myocytes remains unknown. Therefore, we examined the in vitro effects of hyperglycemia on hypoxia-reoxygenation (H/R) and cardioprotection from remifentanil-preconditioning in isolated neonatal rat ventricular myocytes (NRVMs), including effects on apoptotic signaling pathways and Ca(2+) homeostasis.

MATERIALS AND METHODS

NRVMs were cultured in medium with 5.5 mM (normoglycemia) or 25.5 mM glucose for one day. Then, NRVMs in H/R groups were exposed to 1 h of hypoxia and 5 h of reoxygenation with or without remifentanil-preconditioning at 1 μM. Cell viability, apoptosis, and Ca(2+) homeostasis were assessed by MTT assay, caspase-3 assay, confocal microscopy and immunoblots.

RESULTS

In normoglycemia, remifentanil-preconditioning improved the viability of cardiomyocytes (P < 0.01) and prevented the increase of caspase-3 activity and Ca(2+) overload after H/R injury (P < 0.05). In addition, decrease in Akt, ERK1/2, and Bcl-2, and the increase in Bax by H/R was attenuated by remifentanil-preconditioning (P < 0.05). However, in hyperglycemia, the viability was partially impaired after H/R but not improved by remifentanil-preconditioning. Apoptotic activity, Ca(2+) concentration, and apoptotic kinases except Akt were not affected by either H/R or remifentanil-preconditioning under hyperglycemia. Akt phosphorylation was decreased by H/R but not restored by remifentanil preconditioning.

CONCLUSIONS

Remifentanil preconditioning under normoglycemia renders NRVMs resistant to H/R injury by reducing apoptosis and intracellular Ca(2+) concentrations. The mechanism appears to be modulation of apoptotic signaling. However, hyperglycemia mitigates H/R injury in NRVMs, and may reduce the protective effect of remifentanil-preconditioning that may be associated with the Akt pathways.

The second window of preconditioning (SWOP) where are we now?

A standard ischemic preconditioning (IPC) stimulus of one or more brief episodes of non-lethal myocardial ischemia and reperfusion elicits a bi-phasic pattern of cardioprotection. The first phase manifests almost immediately following the IPC stimulus and lasts for 1-2 h, after which its effect disappears (termed classical or early IPC). The second phase of cardioprotection appears 12-24 h later and lasts for 48-72 h (termed the Second Window of Protection [SWOP] or delayed or late IPC). The cardioprotection conferred by delayed IPC is robust and ubiquitous but is not as powerful as early IPC. Although there are some similarities in the mechanisms underlying early and delayed IPC, one of the major distinctions between the two is the latter's requirement for de novo protein synthesis of distal mediators such as iNOS and COX-2 which mediate the cardioprotection 24 h after the IPC stimulus. The phenomenon of delayed IPC has been demonstrated in man using a variety of experimental models. However, its clinical application has been limited by the same factors which affect early IPC- i.e. the need to intervene before the onset of myocardial ischemia, thereby restricting its potential clinical utility to planned settings of acute myocardial ischemia-reperfusion injury such as coronary artery bypass graft surgery, cardiac transplantation and percutaneous coronary intervention. In this article, the focus will be on the origins of delayed IPC, the mechanisms underlying its delayed cardioprotective effect, and the potential areas for its clinical application.

Remifentanil post-conditioning attenuates cardiac ischemia-reperfusion injury via kappa or delta opioid receptor activation

BACKGROUND

Ischemic pre- or post-conditioning of the heart has been shown to involve opioid receptors. Remifentanil, an ultra-short-acting selective mu opioid receptor agonist in clinical use, pre-conditions the rat heart against ischemia-reperfusion injury. This study investigates whether remifentanil post-conditioning is also cardioprotective.

METHODS

Remifentanil post-conditioning (5-min infusion at 1, 5, 10 or 20 microg/kg/min) or ischemic post-conditioning (three cycles of a 10 s reperfusion interspersed with a 10 s ischemia) was induced in an open-chest rat heart model of ischemia and reperfusion injury, in the presence or absence of nor-binaltorphimine, naltrindole or CTOP, specific kappa, delta and mu opioid receptor antagonists, respectively. The same sequence of experiments was repeated in the isolated heart model using the maximal protective dose of remifentanil from the dose-response studies.

RESULTS

Both ischemic and remifentanil post-conditioning reduced the myocardial infarct size relative to the control group in both models. This cardioprotective effect for both post-conditioning regimes was prevented by the prior administration of nor-binaltorphimine and naltrindole but not CTOP. The sole administration of the antagonists had no effect on the size of myocardial infarction.

CONCLUSIONS

These results indicate that remifentanil post-conditioning protects the heart from ischemia-reperfusion injury to a similar extent as of ischemic post-conditioning. This protection involves kappa and delta but not mu opioid receptor activation. This drug has great potential as a clinical post-conditioning modality as it can be given in large doses without prolonged opioid-related side effects.

Diabetes mellitus mitigates cardioprotective effects of remifentanil preconditioning in ischemia-reperfused rat heart in association with anti-apoptotic pathways of survival

Diabetes mellitus has been known to mitigate ischemic or pharmacologic preconditioning in ischemia-reperfusion injuries. Remifentanil is a widely used opioid in cardiac anesthesia that possesses a cardioprotective effect against ischemia-reperfusion. We evaluated whether diabetes affected remifentanil preconditioning induced cardioprotection in ischemia-reperfusion rat hearts in view of anti-apoptotic pathways of survival and Ca(2+) homeostasis. Streptozotocin-induced, diabetic rats and age-matched wild-type Sprague-Dawley rats were subjected to a left anterior descending coronary artery occlusion for 30min followed by 1h of reperfusion. Each diabetic and wild-type rat was randomly assigned to the sham, ischemia-reperfusion only, or remifentanil preconditioning group. Myocardial infarct size, activities of ERK1/2, Bcl2, Bax and cytochrome c, and gene expression influencing Ca(2+) homeostasis were assessed. Remifentanil preconditioning significantly reduced myocardial infarct size compared to ischemia-reperfusion only in wild-type rats but not in diabetic rats. Remifentanil preconditioning increased expression of ERK1/2 and anti-apoptotic protein Bcl-2 and decreased expression of pro-apoptotic proteins, Bax and cytochrome c, compared to ischemia-reperfusion only in wild-type rats. In diabetic rat hearts, however, remifentanil preconditioning failed to recover the phosphorylation state of ERK1/2 and to repress apoptotic signaling. In addition, diabetes minimized remifentanil induced modulation of abnormal changes in sarcoplasmic reticulum genes and proteins in ischemia-reperfusion rat hearts. In conclusion, diabetes mitigated remifentanil induced cardioprotection against ischemia-reperfusion, which might be associated with reduced recovery of the activities of proteins involved in anti-apoptotic pathways including ERK1/2 and the abnormal expression of sarcoplasmic reticulum genes as a result of ischemia-reperfusion in rat hearts.

[Anaesthesiologic implications of the radial approach in interventional cardiology]

The development of the radial approach in interventional cardiology is one of the reasons for the increase in demands for anaesthesia services in the cardiac catheterization room. The technique in which sedation is carried out in this particular environment has gradually changed, in parallel with the development of new technologies in anaesthesia, particularly suited to achieving short sedation in spontaneous ventilation. This article evaluates this issue and suggests an updated therapeutic approach.

Anaesthesia and myocardial ischaemia/reperfusion injury

Anaesthetists are confronted on a daily basis with patients with coronary artery disease, myocardial ischaemia, or both during the perioperative period. Therefore, prevention and ultimately adequate therapy of perioperative myocardial ischaemia and its consequences are the major challenges in current anaesthetic practice. This review will focus on the translation of the laboratory evidence of anaesthetic-induced cardioprotection into daily clinical practice.

Endogenous opiates and behavior: 2007

This paper is the thirtieth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2007 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.