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

Inhibitory role of remifentanil in hepatic ischemia-reperfusion injury through activation of Fmol/Parkin signaling pathway: A study based on network pharmacology analysis and high-throughput sequencing

BACKGROUND

This study was conducted to elucidate the critical molecular pathways underlying the protective effects of remifentanil against hepatic ischemia-reperfusion injury in rats. Our approach integrated network pharmacology analysis with high-throughput sequencing to achieve a comprehensive understanding of the mechanisms involved.

STUDY DESIGN/METHODS

The study utilized GSE24430 gene expression data from GEO to investigate remifentanil's impact on Hepatic Ischemia-Reperfusion Injury in rats. Weighted Correlation Network Analysis (WGCNA) was employed to pinpoint crucial genes and identify modules of co-expressed genes. Differential analysis with the "Limma" package revealed genes differentially expressed in IRI vs. control groups. PubChem and PharmMapper provided target genes affected by remifentanil. Protein-protein interaction networks were constructed via GeneCards and STRING. Functional analysis pinpointed core genes involved in remifentanil's IRI alleviation. IRI rat models were established, and hepatic injury indicators, liver structure via H&E staining, autophagosome counts via electron microscopy, and gene/protein expression via RT-qPCR and Western blot were assessed. High-throughput sequencing analyzed molecular pathways affected by varying remifentanil doses in IRI rats.

RESULTS

In the study, we discovered four primary co-expression modules associated with hepatic IRI, and the grey module exhibited the highest correlation with hepatic IRI.A total of sixty-eight genes that were differentially expressed were found to have a connection with hepatic IRI.Network pharmacology analysis found that remifentanil may alleviate hepatic IRI through Fmol.found that the Fmol/Parkin signaling pathway may alleviate hepatic IRI via Additionally, the database autophagy. The established hepatic IRI rat models further confirmed the above findings.

CONCLUSION

Our study established that remifentanil triggers the Fmol/Parkin signaling cascade, amplifying the expression levels of Fmol and Parkin. This process culminates in the activation of autophagy within hepatic cells, ultimately alleviating hepatic ischemia-reperfusion injury (IRI).

Targeting the opioid remifentanil: Protective effects and molecular mechanisms against organ ischemia-reperfusion injury

Opioids are widely used in clinical practice by activating opioid receptors (OPRs), but their clinical application is limited by a series of side effects. Researchers have been making tremendous efforts to promote the development and application of opioids. Fortunately, recent studies have identified the additional effects of opioids in addition to anesthesia and analgesia, particularly in terms of organ protection against ischemia-reperfusion (I/R) injury, with unique advantages. I/R injury in vital organs not only leads to cell dysfunction and structural damage but also induces acute and chronic organ failure, even death. Early prevention and appropriate therapeutic targets for I/R injury are crucial for organ protection. Opioids have shown cardioprotective effects for over 20 years, especially remifentanil, a derivative of fentanyl, which is a new ultra-short-acting opioid analgesic widely used in clinical anesthesia induction and maintenance. In this review, we provide current knowledge about the physiological effects related to OPR-mediated organ protection, focusing on the protective effect and mechanism of remifentanil on I/R injury in the heart and other vital organs. Herein, we also explored the potential application of remifentanil in clinical I/R injury. These findings provide a theoretical basis for the use of remifentanil to inhibit or alleviate organ I/R injury during the perioperative period and provide insights for opioid-induced human organ protection and drug development.

Effect of Analgesic Opioid Drugs on Opioid Receptor Genes Expression in HL-1 Mouse Cardiac Myocytes

BACKGROUND: The opioid system was mainly involved three types of opioid receptors (ORs): μ (MOR), δ (DOR) and κ (KOR). These ORs are activated by its agonist, a family of endogenous peptides: Endorphins, enkephalins, and dynorphins, respectively. AIM: This study determined the OR mRNA on effects of agonists exogenous morphine, fentanyl, D-penicillamine (2,5) enkephalin, and ketazocine in HL-1 mouse cardiac myocytes. MATERIALS AND METHODS: HL-1 mouse cardiac myocytes were treated with 10 μM morphine sulfate, 1 μM fentanyl,1 μM D-penicillamine (2,5) enkephalin, and 1 μM ketazocine. Total mRNAs were extracted and cDNA was synthesized and quantitative real-time polymerase chain reaction was used to analyze gene expression. RESULTS: The data analysis of MOR, DOR and KOR mRNA expression on effect of morphine was shown less level than control (0.61-fold, 0.67-fold, and 0.65-fold), respectively. The morphine-induced ORs down-regulation, whereas enkephalin treatment demonstrated highly significantly increased in mRNA of DOR (6.3-fold, p = 0.002). As well as, KOR mRNA expression was found highly significant increased under effect of Ketazocine (7.16-fold, p = 0.004). CONCLUSION: This study found DOR and KOR, but not MOR expressed in HL-1 mouse cardiac myocytes under activation of exogenous opioid analogists. These findings suggested that exogenous analogist’s opioids mimeses the endogenous analogist’s opioids.

Perioperative Cardioprotection: Clinical Implications

Perioperative cardioprotection aims to minimize the consequences of myocardial ischemia-reperfusion injury. In isolated tissue and animal experiments, several treatments have been identified providing cardioprotection. Some of these strategies have been confirmed in clinical proof-of-concept studies. However, the final translation of cardioprotective strategies to really improve clinical outcome has been disappointing: large randomized controlled clinical trials mostly revealed inconclusive, neutral, or negative results. This review provides an overview of the currently available evidence regarding clinical implications of perioperative cardioprotective therapies from an anesthesiological perspective, highlighting nonpharmacological as well as pharmacological strategies. We discuss reasons why translation of promising experimental results into clinical practice and outcome improvement is hampered by potential confounders and suggest future perspectives to overcome these limitations.

Remifentanil up-regulates HIF1α expression to ameliorate hepatic ischaemia/reperfusion injury via the ZEB1/LIF axis

Ischaemia/reperfusion (I/R)-induced hepatic injury is regarded as a main reason of hepatic failure after transplantation or lobectomy. The current study aimed to investigate how the opioid analgesic remifentanil treatment affects I/R-induced hepatic injury and explore the possible mechanisms related to HIF1α. Initially, an I/R-induced hepatic injury animal model was established in C57BL/6 mice, and an in vitro hypoxia-reoxygenation model was constructed in NCTC-1469 cells, followed by remifentanil treatment and HIF1α silencing treatment. The levels of blood glucose, lipids, alanine transaminase (ALT) and aspartate transaminase (AST) in mouse serum were measured using automatic chemistry analyser, while the viability and apoptosis of cells were detected using CCK8 assay and flow cytometry. Our results revealed that mice with I/R-induced hepatic injury showed higher serum levels of blood glucose, lipids, ALT and AST and leukaemia inhibitory factor (LIF) expression, and lower HIF1α and ZEB1 expression (P < .05), which were reversed after remifentanil treatment (P < .05). Besides, HIF1α silencing increased the serum levels of blood glucose, lipids, ALT and AST (P < .05). Furthermore, hypoxia-induced NCTC-1469 cells exhibited decreased HIF1α and ZEB1 expression, reduced cell viability, as well as increased LIF expression and cell apoptosis (P < .05), which were reversed by remifentanil treatment (P < .05). Moreover, HIF1α silencing down-regulated ZEB1 expression, decreased cell viability, and increased cell apoptosis (P < .05). ZEB1 was identified to bind to the promoter region of LIF and inhibit its expression. In summary, remifentanil protects against hepatic I/R injury through HIF1α and downstream effectors.

Pharmacological postconditioning: a molecular aspect in ischemic injury

OBJECTIVE

Ischaemia/reperfusion (I/R) injury is defined as the damage to the tissue which is caused when blood supply returns to tissue after ischaemia. To protect the ischaemic tissue from irreversible injury, various protective agents have been studied but the benefits have not been clinically applicable due to monotargeting, low potency, late delivery or poor tolerability.

KEY FINDINGS

Strategies involving preconditioning or postconditioning can address the issues related to the failure of protective therapies. In principle, postconditioning (PoCo) is clinically more applicable in the conditions in which there is unannounced ischaemic event. Moreover, PoCo is an attractive beneficial strategy as it can be induced rapidly at the onset of reperfusion via series of brief I/R cycles following a major ischaemic event or it can be induced in a delayed manner. Various pharmacological postconditioning (pPoCo) mechanisms have been investigated systematically. Using different animal models, most of the studies on pPoCo have been carried out preclinically.

SUMMARY

However, there is a need for the optimization of the clinical protocols to quicken pPoCo clinical translation for future studies. This review summarizes the involvement of various receptors and signalling pathways in the protective mechanisms of pPoCo.

Autocrine Bradykinin Release Promotes Ischemic Preconditioning-Induced Cytoprotection in Bovine Aortic Endothelial Cells

The aims of this study were to assess whether ischemic preconditioning (PC) induces bradykinin (Bk) synthesis in bovine aortic endothelial cells (bAECs) and, if so, to explore the molecular mechanisms by which this peptide provides cytoprotection against hypoxia. PC was induced by exposing bAECs to three cycles of 15 min of hypoxia followed by 15 min of reoxygenation. Bk synthesis peaked in correspondence to the early and late phases of PC (10⁻¹² M and 10⁻¹¹ M, respectively) and was abolished by a selective tissue kallikrein inhibitor, aprotinin. Stimulation with exogenous Bk at concentrations of 10⁻¹² M and 10⁻¹¹ M reduced the cell death induced by 12 h of hypoxia by 50%. Pretreatment with HOE−140, a Bk receptor 2 (BKR2) inhibitor, in bAECs exposed to 12 h of hypoxia, abrogated the cytoprotective effect of early and late PC, whereas des-Arg-HOE-140, a Bk receptor 1 (BKR1) inhibitor, affected only the late PC. In addition, we found that PC evoked endocytosis and the recycling of BKR2 during both the early and late phases, and that inhibition of these pathways affected PC-mediated cytoprotection. Finally, we evaluated the activation of PKA and Akt in the presence or absence of BKR2 inhibitor. HOE-140 abrogated PKA and Akt activation during both early and late PC. Consistently, BKR2 inhibition abolished cross-talk between PKA and Akt in PC. In bAECs, Bk-synthesis evoked by PC mediates the protection against both apoptotic and necrotic hypoxia-induced cell death in an autocrine manner, by both BKR2- and BKR1-dependent mechanisms.

Remifentanil upregulates hepatic IL-18 binding protein (IL-18BP) expression through transcriptional control

Interleukin (IL)-18 plays an important role in liver ischemia/reperfusion (I/R) injury. We have previously demonstrated that remifentanil protects against liver I/R injury by upregulating the hepatic expression of IL-18-binding protein (IL-18BP), a natural IL-18 inhibitor. The current study was performed to further clarify the effects of remifentanil on IL-18BP expression in the liver as well as investigate the underlying mechanisms. In Sprague-Dawley (SD) rats, we demonstrated that remifentanil significantly increased the expression of IL-18BP in normal rat liver tissue over a 24-h time period with maximal expression at 24 h after treatment. The upregulation of remifentanil on IL-18BP expression displayed similar trends in in vitro cellular studies, including mouse primary hepatocytes, normal human hepatocyte LO2, and mouse hepatoma cells Hep1-6. In LO2 cells, preexposure of the cells to remifentanil significantly inhibited IL-18-activated p65 NF-κB phosphorylation, and the inhibition was absent when the cells were transfected with IL-18BP siRNA, indicating the functional effects of IL-18BP induced by remifentanil. Pretreatment with actinomycin D abolished remifentanil-induced upregulation of IL-18BP mRNA, suggesting that the induction occurred at the transcriptional level. This was further supported by the luciferase reporter assay, which demonstrated that remifentanil treatment significantly increased transcription of the IL-18BP promoter. Both western blot analysis and ChIP assays showed that STAT1 and C/EBP β were activated by remifentanil. Furthermore, remifentanil failed to upregulate IL-18BP expression after silencing STAT1 or C/EBP β gene expression. These findings demonstrate that remifentanil could upregulate hepatic IL-18BP expression through transcriptional activation of the IL-18BP promoter, and STAT1 and C/EBP β are two key transcriptional factors involved in this process.

Intra-coronary morphine versus placebo in the treatment of acute ST-segment elevation myocardial infarction: the MIAMI randomized controlled trial

BACKGROUND

Experimental studies suggest that morphine may protect the myocardium against ischemia-reperfusion injury by activating salvage kinase pathways. The objective of this two-center, randomized, double-blind, controlled trial was to assess potential cardioprotective effects of intra-coronary morphine in patients with ST-segment elevation myocardial infarction (STEMI) referred for primary percutaneous intervention.

METHODS

Ninety-one patients with STEMI were randomly assigned to intracoronary morphine (1 mg) or placebo at reperfusion of the culprit coronary artery. The primary endpoint was infarct size/left ventricular mass ratio assessed by magnetic resonance imaging on day 3-5. Secondary endpoints included the areas under the curve (AUC) for troponin T and creatine kinase over three days, left ventricular ejection fraction assessed by echocardiography on days 1 and 6, and clinical outcomes.

RESULTS

Infarct size/left ventricular mass ratio was not significantly reduced by intracoronary morphine compared to placebo (27.2% ± 15.0% vs. 30.5% ± 10.6%, respectively, p = 0.28). Troponin T and creatine kinase AUCs were similar in the two groups. Morphine did not improve left ventricular ejection fraction on day 1 (49.7 ± 10.3% vs. 49.3 ± 9.3% with placebo, p = 0.84) or day 6 (48.5 ± 10.2% vs. 49.0 ± 8.5% with placebo, p = 0.86). The number of major adverse cardiac events, including stent thrombosis, during the one-year follow-up was similar in the two groups.

CONCLUSIONS

Intracoronary morphine at reperfusion did not significantly reduce infarct size or improve left ventricular systolic function in patients with STEMI. Presence of comorbidities in some patients may contribute to explain these results.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01186445 (date of registration: August 23, 2010).

Remifentanil Preconditioning Attenuates Hepatic Ischemia-Reperfusion Injury in Rats via Neuronal Activation in Dorsal Vagal Complex

Remifentanil, an ultra-short acting opiate, has been reported to protect against hepatic ischemia-reperfusion injury, which is a major cause of postoperative liver dysfunction. The objective of this study was to determine whether a central vagal pathway is involved in this protective procedure. Rat models of hepatic ischemia-reperfusion were used in the experimental procedures. The results revealed that intravenous pretreatment with remifentanil decreased serum aminotransferases and hepatic histologic damage; however, an intraperitoneal injection of μ-opioid receptor antagonist did not abolish the protection of remifentanil preconditioning. c-Fos immunofluorescence of the brain stem showed that dorsal motor nucleus of the vagus was activated after remifentanil preconditioning. Moreover, serum alanine aminotransferase, histopathologic damage, and apoptosis decreased in remifentanil preconditioning group compared to vagotomized animals with remifentanil preconditioning, and there was no statistical difference of TNF-α and IL-6 between NS/Va and RPC/Va groups. In addition, remifentanil microinjection into dorsal vagal complex decreased serum aminotransferases, inflammatory cytokines, and hepatic histologic injury and apoptosis, and these effects were also abolished by a peripheral hepatic vagotomy. In conclusion, remifentanil preconditioning conferred liver protection against ischemia-reperfusion injury, which was mediated by the central vagal pathway.

Hypoxic conditioning in blood vessels and smooth muscle tissues: effects on function, mechanisms, and unknowns

Hypoxic preconditioning, the protective effect of brief, intermittent hypoxic or ischemic episodes on subsequent more severe hypoxic episodes, has been known for 30 yr from studies on cardiac muscle. The concept of hypoxic preconditioning has expanded; excitingly, organs beyond the heart, including the brain, liver, and kidney, also benefit. Preconditioning of vascular and visceral smooth muscles has received less attention despite their obvious importance to health. In addition, there has been no attempt to synthesize the literature in this field. Therefore, in addition to overviewing the current understanding of hypoxic conditioning, in the present review, we consider the role of blood vessels in conditioning and explore evidence for conditioning in other smooth muscles. Where possible, we have distinguished effects on myocytes from other cell types in the visceral organs. We found evidence of a pivotal role for blood vessels in conditioning and for conditioning in other smooth muscle, including the bladder, vascular myocytes, and gastrointestinal tract, and a novel response in the uterus of a hypoxic-induced force increase, which helps maintain contractions during labor. To date, however, there are insufficient data to provide a comprehensive or unifying mechanism for smooth muscles or visceral organs and the effects of conditioning on their function. This also means that no firm conclusions can be drawn as to how differences between smooth muscles in metabolic and contractile activity may contribute to conditioning. Therefore, we have suggested what may be general mechanisms of conditioning occurring in all smooth muscles and tabulated tissue-specific mechanistic findings and suggested ideas for further progress.

Isoflurane's Effect on Intraoperative Systolic Left Ventricular Performance in Cardiac Valve Surgery Patients

BACKGROUND

Isoflurane, a common anesthetic for cardiac surgery, reduced myocardial contractility in many experimental studies, few studies have determined isoflurane's direct impact on the left ventricular (LV) contractile function during cardiac surgery. We determined whether isoflurane dose-dependently reduces the peak systolic velocity of the lateral mitral annulus in tissue Doppler imaging (S') in patients undergoing cardiac surgery.

METHODS

During isoflurane-supplemented remifentanil-based anesthesia for patients undergoing cardiac surgery with preoperative LV ejection fraction greater than 50% (n = 20), we analyzed the changes of S' at each isoflurane dose increment (1.0, 1.5, and 2.0 minimum alveolar concentration [MAC]: T1, T2, and T3, respectively) with a fixed remifentanil dosage (1.0 μg/min/kg) by using transesophageal echocardiography.

RESULTS

Mean S' values (95% confidence interval [CI]) at T1, T2, and T3 were 10.5 (8.8-12.2), 9.5 (8.3-10.8), and 8.4 (7.3-9.5) cm/s, respectively (P < 0.001 in multivariate analysis of variance test). Their mean differences at T1 vs. T2, T2 vs. T3, and T1 vs. T3 were -1.0 (-1.6, -0.3), -1.1 (-1.7, -0.6), and -2.1 (-3.1, -1.1) cm/s, respectively. Phenylephrine infusion rates were significantly increased (0.26, 0.22, and 0.47 μg/kg/min at T1, T2, and T3, respectively, P < 0.001).

CONCLUSION

Isoflurane increments (1.0-2.0 MAC) dose-dependently reduced LV systolic long-axis performance during cardiac surgeries with a preserved preoperative systolic function.

Remifentanil reduced the effects of hydrogen peroxide-induced oxidative stress in human keratinocytes via autophagy

PURPOSE

Excess reactive oxygen species are detrimental to wound repair. Remifentanil decreases reactive oxygen species generation and inflammatory response; however, its effects on oxidative cell injury are not completely understood. Therefore, we investigated the effects of remifentanil on human keratinocytes under hydrogen peroxide-induced oxidative stress and the correlation of these effects with autophagy.

MATERIALS AND METHODS

Human keratinocytes (HaCaT cell line) were randomly assigned to four groups: control, hydrogen peroxide, remifentanil pretreatment + hydrogen peroxide, and 3-methyladenine + remifentanil pretreatment + hydrogen peroxide. The MTT assay was performed to analyze cell viability. Apoptotic cell death was measured by Hoechst staining. A scratch assay was used to measure cell migration. The role of autophagy was ascertained by autophagosome staining and western blot analysis of autophagy-related proteins.

RESULTS

Compared with the control group, the hydrogen peroxide group showed decreased cell viability, which was improved by remifentanil pretreatment. Hydrogen peroxide-induced apoptotic cell death and delayed cell migration were also improved by remifentanil pretreatment. Western blot analysis showed that the expression of autophagy-related proteins significantly increased in the remifentanil pretreatment + hydrogen peroxide group compared with that in the hydrogen peroxide group.

CONCLUSIONS

This study demonstrated that remifentanil pretreatment ameliorates hydrogen peroxide-induced oxidative injury in human keratinocytes. In addition, our results show that the antioxidative effect of remifentanil against hydrogen peroxide-induced oxidative injury was mediated by autophagy.

Sufentanil-medetomidine anaesthesia compared with fentanyl/fluanisone-midazolam is associated with fewer ventricular arrhythmias and death during experimental myocardial infarction in rats and limits infarct size following reperfusion

To improve infarct healing following myocardial infarction in humans, therapeutic interventions can be applied during the inflammatory response. Animal models are widely used to study this process. However, induction of MI in rodents is associated with high mortality due to ventricular fibrillation (VF) during coronary artery ligation. The anaesthetic agent used during the procedure appears to influence the frequency of this complication. In this retrospective study, the effect on ventricular arrhythmia incidence during ligation and infarct size following in vivo reperfusion of two anaesthetic regimens, sufentanil–medetomidine (SM) and fentanyl/fluanisone–midazolam (FFM) was evaluated in rats. Anaesthetics were administered subcutaneously using fentanyl/fluanisone (0.5 mL/kg) with midazolam (5 mg/kg) (FFM group, n = 48) or sufentanil (0.05 mg/kg) with medetomidine (0.15 mg/kg) (SM group, n = 47). The coronary artery was ligated for 40 min to induce MI. Heart rate and ventricular arrhythmias were recorded during ligation, and infarct size was measured via histochemistry after three days of reperfusion. In the SM group, heart rate and VF incidence were lower throughout the experiment compared with the FFM group (6% versus 30%) (P < 0.01). Fatal VF did not occur in the SM group whereas this occurred in 25% of the animals in the FFM group. Additionally, after three days of reperfusion, the infarcted area following SM anaesthesia was less than half as large as that following FFM anaesthesia (8.5 ± 6.4% versus 20.7 ± 5.6%) (P < 0.01). Therefore, to minimize the possibility of complications related to VF and acute death arising during ligation, SM anaesthesia is recommended for experimental MI in rats.

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.

Remifentanil Ameliorates Liver Ischemia-Reperfusion Injury Through Inhibition of Interleukin-18 Signaling

BACKGROUND

Hepatic injury induced by ischemia-reperfusion (I/R) after transplantation or lobectomy is a major clinical problem. The potential benefit of remifentanil in these hepatic surgeries remains unknown. The current study investigated whether remifentanil protects the liver against I/R injury in a rat model and whether the underlying mechanism involves the modulation of interleukin (IL)-18 signaling.

METHODS

Male Sprague-Dawley rats were subjected to 45 minutes of partial hepatic ischemia followed by 6 hours of reperfusion. Then, they received an intravenous saline or remifentanil (0.4, 2, or 10 μg/kg per minute) infusion from 30 minutes before ischemia until the end of ischemia with or without previous administration of naloxone, a nonselective opioid receptor antagonist. Serum aminotransferase, hepatic morphology, and hepatic neutrophil infiltration were analyzed. The expression of hepatic IL-18; IL-18-binding protein (BP); and key cytokines downstream of IL-18 signaling were measured.

RESULTS

Remifentanil significantly decreased serum aminotransferase levels and profoundly attenuated the liver histologic damages. Liver I/R injury increased the expression of both hepatic IL-18 and IL-18BP. Although remifentanil pretreatment significantly decreased I/R-induced IL-18 expression, it further upregulated IL-18BP levels in liver tissues. The I/R-induced increases of hepatic interferon-γ, tumor necrosis factor-α and IL-1β expression, and neutrophil infiltration were also significantly reduced by remifentanil. Naloxone inhibited the remifentanil-induced downregulation of IL-18, but not the elevation of IL-18BP, and significantly attenuated its protective effects on liver I/R injury.

CONCLUSIONS

Remifentanil protects the liver against I/R injury. Modulating the hepatic IL-18/IL-18BP balance and inhibiting IL-18 signaling mediate, at least in part, the hepatoprotective effects of remifentanil.

Featured Article: Pharmacological postconditioning with delta opioid attenuates myocardial reperfusion injury in isolated porcine hearts

Ischemic preconditioning has been utilized to protect the heart from ischemia prior to ischemia onset, whereas postconditioning is employed to minimize the consequences of ischemia at the onset of reperfusion. The underlying mechanisms and pathways of ischemic pre- and postconditioning continue to be investigated as therapeutic targets. We evaluated the administration of a delta opioid agonist or cariporide on various parameters associated with myocardial reperfusion injury upon reperfusion of isolated porcine hearts. The hearts were reperfused in vitro with a Krebs buffer containing either: (1) 1 µM Deltorphin D (delta opioid specific agonist, n = 6); (2) 3 µM cariporide (sodium-hydrogen exchange inhibitor, n = 4); or (3) no treatment (control, n = 6). Subsequently, postischemic hemodynamic performance, arrhythmia burden, relative tissue perfusion, and development of necrosis were assessed over a 2 h reperfusion period. Postconditioning with Deltorphin D significantly improved diastolic relaxation (Tau, P < 0.05 versus controls) and decreased the incidence of ventricular arrhythmias during early reperfusion. Additionally, these treated hearts demonstrated increased tissue perfusion after 2 h ( P < 0.05 versus controls), suggesting improved microvascular function. Delta opioid agonists elicited the potential to attenuate reperfusion injury, suggesting a postconditioning effect of these agents. We hypothesize that the induced benefits of delta opioids, in part, are associated with decreased calcium influx on reperfusion, independent of sodium-hydrogen exchange inhibition. Such agents may have a potential role in minimizing reperfusion injury associated with coronary stenting, bypass surgery, myocardial infarction, cardiac transplantation, or with the utilization of heart preservation systems. Impact statement In this study, we found that postconditioning with Deltorphin D significantly improved diastolic relaxation and decreased the incidence of ventricular arrhythmias during early reperfusion. Furthermore, these treated hearts demonstrated increased tissue perfusion after 2 h, suggesting improved microvascular function. Delta opioid agonists attenuated reperfusion injury, suggestive of a postconditioning effect. Such agents may have a potential role in minimizing reperfusion injury associated with coronary stenting, bypass surgery, myocardial infarction, cardiac transplantation, or with the utilization of heart preservation systems.

Involvement of Opioid Receptors in the Lipid Rescue of Bupivacaine-Induced Cardiotoxicity

BACKGROUND

Lipid emulsion (LE) has been successfully used for resuscitation of local anesthetic cardiotoxicity caused by bupivacaine overdose. Opioid receptors have been shown to play a key role in cardio protection. We explored whether this rescue action of LE is mediated through opioid receptors.

METHODS

Asystole was induced by bupivacaine (10 mg/kg over 20 seconds, IV) in young male Sprague-Dawley rats, and resuscitation with LE (intralipid 20%; 5 mL/kg bolus and 0.5 mL/kg/min maintenance) was started immediately. The rats were pretreated 2 minutes before inducing asystole with nonselective opioid receptor antagonists such as naloxone and naloxone methiodide, as well as highly selective opioid receptor antagonists for subtype κ, δ, and µ or phosphate buffer solution as a control. Heart rates and ejection fractions were measured using echocardiography.

RESULTS

LE rescue of bupivacaine cardiotoxicity was prevented by high-dose (1 mg/kg) naloxone but not by lower doses of naloxone (1, 5, and 10 µg/kg), by naloxone methiodide (which does not cross the blood-brain barrier), and by a selective δ- and κ-opioid receptor antagonists at a higher (10 mg/kg) dose. Successful LE rescue was not affected by highly selective µ-opioid receptor antagonists. δ-Opioid receptor antagonist (10 mg/kg) pretreatment also resulted in reduced phosphorylation level of cardiac glycogen synthase kinase-3β in rats that were not resuscitated by LE compared with control.

CONCLUSIONS

Our data highlight the involvement of peripheral δ- and κ-opioid receptors in the rescue action of LE.

Molecular basis of cardioprotection: signal transduction in ischemic pre-, post-, and remote conditioning

Reperfusion is mandatory to salvage ischemic myocardium from infarction, but reperfusion per se contributes to injury and ultimate infarct size. Therefore, cardioprotection beyond that by timely reperfusion is needed to reduce infarct size and improve the prognosis of patients with acute myocardial infarction. The conditioning phenomena provide such cardioprotection, insofar as brief episodes of coronary occlusion/reperfusion preceding (ischemic preconditioning) or following (ischemic postconditioning) sustained myocardial ischemia with reperfusion reduce infarct size. Even ischemia/reperfusion in organs remote from the heart provides cardioprotection (remote ischemic conditioning). The present review characterizes the signal transduction underlying the conditioning phenomena, including their physical and chemical triggers, intracellular signal transduction, and effector mechanisms, notably in the mitochondria. Cardioprotective signal transduction appears as a highly concerted spatiotemporal program. Although the translation of ischemic postconditioning and remote ischemic conditioning protocols to patients with acute myocardial infarction has been fairly successful, the pharmacological recruitment of cardioprotective signaling has been largely disappointing to date.

Opioid receptors and cardioprotection - 'opioidergic conditioning' of the heart

Ischaemic heart disease (IHD) remains a major cause of morbidity/mortality globally, firmly established in Westernized or 'developed' countries and rising in prevalence in developing nations. Thus, cardioprotective therapies to limit myocardial damage with associated ischaemia-reperfusion (I-R), during infarction or surgical ischaemia, is a very important, although still elusive, clinical goal. The opioid receptor system, encompassing the δ (vas deferens), κ (ketocyclazocine) and μ (morphine) opioid receptors and their endogenous opioid ligands (endorphins, dynorphins, enkephalins), appears as a logical candidate for such exploitation. This regulatory system may orchestrate organism and organ responses to stress, induces mammalian hibernation and associated metabolic protection, triggers powerful adaptive stress resistance in response to ischaemia/hypoxia (preconditioning), and mediates cardiac benefit stemming from physical activity. In addition to direct myocardial actions, central opioid receptor signalling may also enhance the ability of the heart to withstand I-R injury. The δ- and κ-opioid receptors are strongly implicated in cardioprotection across models and species (including anti-infarct and anti-arrhythmic actions), with mixed evidence for μ opioid receptor-dependent protection in animal and human tissues. A small number of clinical trials have provided evidence of cardiac benefit from morphine or remifentanil in cardiopulmonary bypass or coronary angioplasty patients, although further trials of subtype-specific opioid receptor agonists are needed. The precise roles and utility of this GPCR family in healthy and diseased human myocardium, and in mediating central and peripheral survival responses, warrant further investigation, as do the putative negative influences of ageing, IHD co-morbidities, and relevant drugs on opioid receptor signalling and protective responses.

Lack of Benefit of Ischemic Postconditioning After Routine Thrombus Aspiration During Reperfusion

Objectives:

The underutilization of manual thrombus aspiration (MTA) may have reduced the benefits of ischemic postconditioning (PostCon), as it reduces thrombus embolization. We aimed to assess the benefits of PostCon in patients with ST-segment elevation myocardial infarction (STEMI) after the systematic utilization of MTA.

Methods:

A total of 87 patients were enrolled in a prospective, randomized trial (43 PostCon and 44 controls). After MTA, PostCon was performed on the treatment group by applying 4 cycles of alternate reperfusion and reocclusion (60 seconds each) using the angioplasty balloon. The primary end point was infarct size assessed by the area under the curve (AUC) of troponin T (TnT) activity. The secondary end points were left ventricle ejection fraction (LVEF) and major cardiac events (new myocardial infarction or cardiac death) both at discharge and at follow-up.

Results:

The AUC for TnT was no different with respect to study arms (median [interquartile range]): PostCon = 8.9 (10.6) versus control = 8.2 (10.6), P = .68. Left ventricle ejection fraction improved from in-hospital to follow-up (9 ± 3 months) for the entire cohort (46.3% ± 7.3% vs 52.2% ± 10.7%, P < .001), with no differences between PostCon and controls (51.6% ± 9.5% vs 52.7% ± 11.9%, P = .89); major cardiac events at 14 ± 4 months of follow-up were also no different (PostCon = 1.0 (2.3%) vs control = 0, P = .49).

Conclusion:

In patients with STEMI treated with MTA, PostCon offered no benefits to infarct size, LVEF, or major cardiac events.

Extracellular signalling molecules in the ischaemic/reperfused heart - druggable and translatable for cardioprotection?

In patients with acute myocardial infarction, timely reperfusion is essential to limit infarct size. However, reperfusion also adds to myocardial injury. Brief episodes of ischaemia/reperfusion in the myocardium or on organ remote from the heart, before or shortly after sustained myocardial ischaemia effectively reduce infarct size, provided there is eventual reperfusion. Such conditioning phenomena have been established in many experimental studies and also translated to humans. The underlying signal transduction, that is the molecular identity of triggers, mediators and effectors, is not clear yet in detail, but several extracellular signalling molecules, such as adenosine, bradykinin and opioids, have been identified to contribute to cardioprotection by conditioning manoeuvres. Several trials have attempted the translation of cardioprotection by such autacoids into a clinical scenario of myocardial ischaemia and reperfusion. Adenosine and its selective agonists reduced infarct size in a few studies, but this benefit was not translated into improved clinical outcome. All studies with bradykinin or drugs which increase bradykinin's bioavailability reported reduced infarct size and some of them also improved clinical outcome. Synthetic opioid agonists did not result in a robust infarct size reduction, but this failure of translation may relate to the cardioprotective properties of the underlying anaesthesia per se or of the comparator drugs. The translation of findings in healthy, young animals with acute coronary occlusion/reperfusion to patients of older age, with a variety of co-morbidities and co-medications, suffering from different scenarios of myocardial ischaemia/reperfusion remains a challenge.

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.

Naloxone Postconditioning Alleviates Rat Myocardial Ischemia Reperfusion Injury by Inhibiting JNK Activity

To investigate the alteration of c-Jun N-terminal kinase (JNK) activity after myocardial ischemia reperfusion injury (MIRI) and further explore the effect of naloxone postconditioning on MIRI. Forty male Sprague Dawley rats were randomly divided into five groups: sham operation (sham, n=8); ischemia reperfusion (IR, n=8); IR+naloxone 0.5 mg/kg (Nal L, n=8); IR+naloxone 1.0 mg/kg (Nal M, n=8); IR+naloxone 2.0 mg/kg (Nal H, n=8). Pathological changes of myocardial tissue were visualized by HE staining. The expression of p-JNK, and the apoptosis of cardiomyocytes were investigated with Western blotting and the TUNEL assay, respectively. Irregular arrangement and aberrant structure of myocardial fibers, cardiomyocytes with granular or vacuolar degeneration, and inflammatory cells infiltrating the myocardial interstitial regions characterized MIRI in the IR group. Signs of myocardial injury and inflammatory infiltration were less prominent in the Nal-treated groups. The expression of p-JNK in the sham group and in all Nal-treated groups was significantly lower than that in the IR group (p<0.01). The apoptosis index of cardiomyocytes in the IR group was significantly higher than in the sham group (p< 0.01). The apoptosis indices of cardiomyocytes in all Nal-treated groups were significantly reduced to 55.4%, 26.2%, and 27.6%, respectively, of the IR group (p< 0.01). This study revealed that Naloxone postconditioning before reperfusion inhibits p-JNK expression and decreases cell apoptosis, thus alleviating MIRI.

The effect of intravenous anesthetics on ischemia-reperfusion injury

The effects of intravenous anesthetics on ischemia-reperfusion injury (IRI) have been investigated in both animals and clinical studies. The protective effects and the dosages of the intravenous anesthetics on IRI were discussed in this paper. The prevention of the tissue injury after the IRI was demonstrated with intravenous anesthetics in some studies. In the future, the studies should be focused on the dosage of the anesthetics related to diminishing the tissue injuries. Further studies might be required in order to investigate the effects of the anesthetics on molecular levels.

Pharmacologic therapy that simulates conditioning for cardiac ischemic/reperfusion injury

Cardiovascular disease remains a leading cause of deaths due to noncommunicable diseases, of which ischemic heart disease forms a large percentage. The main therapeutic strategy to treat ischemic heart disease is reperfusion that could either be medical or surgical. However, reperfusion following ischemia is known to increase the infarct size further. Newer strategies such as ischemic preconditioning (IPC), ischemic postconditioning, and remote IPC have been shown to condition the myocardium to ischemia-reperfusion injury and thus reduce the final infarct size. Research over the past 3 decades has deepened our understanding of cellular and subcellular pathways that mediate ischemia-reperfusion injury. This in turn has resulted in the development of several pharmacological agents that act as conditioning agents, which reduce the final myocardial infarct size following ischemia-reperfusion. This review discusses many of these agents, their mechanisms of action, and the animal and clinical evidence behind them.

[D-Ala2,D-Leu5]-enkephalin (DADLE) and morphine-induced postconditioning by inhibition of mitochondrial permeability transition pore, in human myocardium

The aim of the study was to examine the cardioprotective effect of morphine and Delta 2 opioid D-Ala2-Leu5 enkephalin(DADLE) administered, at early reoxygenation, in isolated human myocardium exposed to hypoxia–reoxygenation. Then,we tested the involvement of mitochondrial permeability transition pore in morphine and DADLE-induced postconditioning.Human right atrial trabeculae were obtained during cardiac surgery (coronary artery bypass and aortic valve replacement).Isometrically contracting isolated human right atrial trabeculae were exposed to 30-min hypoxia and 60-min reoxygenation(control group). In treatment groups, morphine 0.5 mmol, DADLE 10 nmol, DADLE 50 nmol and DADLE 100 nmol were administered during the first 15 min of reoxygenation. In two additional groups, morphine and DADLE 100 nmol were administered in the presence of atractyloside 50 mmol, the mitochondrial permeability transition pore opener. The force of contraction at the end of 60-min reoxygenation period (FoC60 expressed as % of baseline) was compared (mean+standard deviation) between the groups by an analysis of variance. Morphine (FoC60: 81+9% of baseline), DADLE50 nmol (FoC60: 76+11% of baseline) and DADLE 100 nmol (FoC60: 81+4% of baseline) increased significantly (P,0.001) the FoC60 as compared with the control group (FoC60: 53+3% of baseline). DADLE 10 nmol did not modify the FoC60 (50+9% of baseline; P ¼ 0.60 versus control group). The enhanced recovery of FoC60 induced by morphine and DADLE 100 nmol were abolished in the presence of atractyloside (FoC60: respectively 57+6% and 44+7% of baseline;P, 0.001). In conclusion, the administration of morphine and DADLE, in early reoxygenation period, protected human myocardium, in vitro, against hypoxia–reoxygenation injury, at least in part, by the inhibition of mitochondrial permeability transition pore opening.

Remifentanil ameliorates intestinal ischemia-reperfusion injury

Background

Intestinal ischemia-reperfusion injury (IRI) can occur in clinical scenarios such as organ transplantation, trauma and cardio-pulmonary bypass, as well as in neonatal necrotizing enterocolitis or persistent ductus arteriosus. Pharmacological protection by pretreating (“preconditioning”) with opioids attenuates IRI in a number of organs. Remifentanil appears particularly attractive for this purpose because of its ultra-short duration of action and favorable safety profile. To date, little is known about opioid preconditioning of the intestine.

Methods

Young adult C57BL/6J mice were randomly assigned to receive tail vein injections of 1 μg/kg of remifentanil or normal saline and underwent either ischemia-reperfusion of the intestine or a sham laparotomy. Under isoflurane anesthesia, the mice were subjected to intestinal ischemia-reperfusion by occlusion (clamping) of the superior mesenteric artery for 30 min, followed by unclamping and 60 min of reperfusion. After completion of this protocol, tissue injury and lipid peroxidation in jejunum and ileum were analyzed by histology and malondialdehyde (MDA), respectively. Systemic interleukin (IL)-6 was determined in the plasma by ELISA.

Results

Pretreatment with remifentanil markedly reduced intestinal IRI (P < 0.001): In the ileum, we observed a more than 8-fold decrease in injured villi (4% vs 34% in saline-pretreated animals). In fact, the mucosa in the remifentanil group was as healthy as that of sham-operated animals. This protective effect was not as pronounced in the jejunum, but the percentage of damaged villi was still reduced considerably (18% vs 42%). There was up to 3-fold more tissue MDA after intestinal ischemia-reperfusion than after sham laparotomy, but this increase in lipid peroxidation was prevented by preconditioning with remifentanil (P < 0.05). The systemic inflammatory response triggered by intestinal IRI was significantly attenuated in mice pretreated with remifentanil (159 vs 805 pg/ml of IL-6 after saline pretreatment, with 92 pg/ml in the sham groups). After sham operations, no difference was detected between the saline- and remifentanil-pretreatments in any of the parameters investigated.

Conclusion

Preconditioning with remifentanil attenuates intestinal IRI and the subsequent systemic inflammatory response in mice. We therefore suggest that prophylaxis with this ultra-short-acting opioid may be advantageous in various clinical scenarios of human IRI.

Diabetes mellitus abrogates the cardioprotection of sufentanil against ischaemia/reperfusion injury by altering glycogen synthase kinase-3β

BACKGROUND

Sufentanil is widely used in clinical anaesthesia because of its protective effects against ischaemia/reperfusion injury. Diabetes mellitus elevates the activity of glycogen synthase kinase-3β (GSK-3β), thereby increasing the permeability of mitochondrial transition pore. This study investigated the role of GSK-3β in ameliorating the cardioprotective effect of sufentanil post-conditioning in diabetic rats.

METHODS

Streptozotocin-induced diabetic rats and age-matched non-diabetic rats were subjected to 30 min of ischaemia and 120 min of reperfusion. Five minutes before reperfusion, rats were administered one of the following: a vehicle, sufentanil (1 μg/kg), or a GSK-3β inhibitor SB216763 (0.6 mg/kg). Myocardial infarct size, cardiac troponin I, and the activity of GSK-3β were then assessed.

RESULTS

Sufentanil post-conditioning significantly reduced myocardial infarct size in the non-diabetic, but not in diabetic rats. SB216763 reduced infarct size in both diabetic and non-diabetic animals. Sufentanil-induced phospho-GSK-3β was reduced 5 min after reperfusion in diabetic rats, but not in non-diabetic rats.

CONCLUSIONS

Sufentanil treatment was ineffective in preventing against ischaemia/reperfusion in diabetic rats, which is associated with the activation of GSK-3β. Our results also suggest that direct inhibition of GSK-3β may provide a strategy to protect diabetic hearts against ischaemia/reperfusion injury.

High-dose remifentanil prevents development of thermal hyperalgesia in a neuropathic pain model

BACKGROUND

Intraoperative nerve lesions can lead to chronic postoperative pain. There are conflicting data as to whether or not anaesthetics administered intraoperatively are beneficial. We investigated if remifentanil administered at the time of nerve injury was able to attenuate neuropathic hypersensitivity.

METHODS

Rats were anaesthetized with isoflurane, endotracheally intubated, and a tail vein catheter was inserted. Rats received an i.v. infusion of either saline or low- or high-dose remifentanil (2 or 20 μg kg(-1) min(-1), respectively) for 20 min. During this time, rats received a spinal nerve L5 transection to induce neuropathic pain or a sham procedure. Behavioural tests to assess mechanical and cold allodynia and heat hyperalgesia were performed on postoperative days 1, 3, 7, 14, 21, and 28.

RESULTS

Sham-operated animals exhibited no hypersensitivity regardless of the intraoperative remifentanil dose. In rats which received spinal nerve L5 transection, mechanical and cold allodynia developed with no significant differences between treatment groups. However, thermal hyperalgesia was reduced in rats given high-dose remifentanil: mean (standard deviation) area under the curve 426 (53) compared with 363 (34) and 342 (24) in saline or low-dose remifentanil treated rats, respectively (P<0.05).

CONCLUSIONS

High-dose remifentanil administered at the time of transection of the spinal nerve at L5 prevents subsequent thermal hyperalgesia.

Sufentanil postconditioning protects the myocardium from ischemia-reperfusion via PI3K/Akt-GSK-3β pathway

BACKGROUND

Previous studies have shown that opioid postconditioning reduces apoptosis through antiapoptotic signaling. The present study evaluated whether sufentanil could induce cardioprotection after ischemia-reperfusion (I/R) and whether the PI3K/Akt-GSK-3β pathway modulates antiapoptotic proteins in sufentanil postconditioning.

METHODS

We subjected male Sprague-Dawley rats to 30 min of myocardial ischemia and 2 h of reperfusion. We randomized rats into seven groups: sham, I/R, sufentanil postconditioning (I/R+sufen), sham plus sufentanil (sham+sufen), sham plus 15 μg · kg(-1) intravenous wortmannin (PI3K inhibitor), I/R plus wortmannin, and sufentanil plus wortmannin. We induced sufentanil postconditioning with 3 μg · kg(-1) sufentanil for 3 min in the beginning of reperfusion after 30 min ischemia. We assessed hemodynamics, myocardial infarct size, number of apoptotic cardiomyocytes, total Akt and GSK-3β, phosphorylated Akt and GSK-3β, caspase-3, Bax, and Bcl-2 protein expression.

RESULTS

The I/R+sufen group had significantly reduced infarct size compared with the I/R group (23.3% ± 9.0% versus 50.1% ± 7.4%; P < 0.05). The apoptotic index of cardiomyocytes was significantly reduced with sufentanil treatment (20.0% ± 3.5%) compared with the I/R group (47.0% ± 6.3%; P < 0.05). The I/R+sufen group reduced the expression of protein-cleaved caspase-3 and Bax, and increased Bcl-2, phosphorylated Akt, and GSK3β compared with the I/R group. Wortmannin eliminated the cardioprotection produced with sufentanil treatment.

CONCLUSIONS

Sufentanil postconditioning can induce myocardial protection by activating the PI3K/Akt-GSK-3β pathway and modulating Bax and Bcl-2 expression.

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.

Endogenous opiates and behavior: 2010

This paper is the thirty-third consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2010 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 (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration (Section 16); and immunological responses (Section 17).

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.