Effects of halothane, isoflurane and sevoflurane on ischemia-reperfusion injury in the perfused liver of fasted rats

Experimental and Clinical Aspects of Sevoflurane Preconditioning and Postconditioning to Alleviate Hepatic Ischemia-Reperfusion Injury: A Scoping Review

Ischemia-reperfusion injury (IRI) is an inflammatory process inherent in organ transplantation procedures. It is associated with tissue damage and, depending on its intensity, can impact early graft function. In liver transplantation (LT), strategies to alleviate IRI are essential in order to increase the use of extended criteria donor (ECD) grafts, which are more susceptible to IRI, as well as to improve postoperative graft and patient outcomes. Sevoflurane, a commonly used volatile anesthetic, has been shown to reduce IRI. This scoping review aims to give a comprehensive overview of the existing experimental and clinical data regarding the potential benefits of sevoflurane for hepatic IRI (HIRI) and to identify any gaps in knowledge to guide further research. We searched Medline and Embase for relevant articles. A total of 380 articles were identified, 45 of which were included in this review. In most experimental studies, the use of sevoflurane was associated with a significant decrease in biomarkers of acute liver damage and oxidative stress. Administration of sevoflurane before hepatic ischemia (preconditioning) or after reperfusion (postconditioning) appears to be protective. However, in the clinical setting, results are conflicting. While some studies showed a reduction of postoperative markers of liver injury, the benefit of sevoflurane on clinical outcomes and graft survival remains unclear. Further prospective clinical trials remain necessary to assess the clinical relevance of the use of sevoflurane as a protective factor against HIRI.

Comparison of Inflammatory Markers Between the Sevoflurane and Isoflurane Anesthesia in a Rat Model of Liver Ischemia/Reperfusion Injury

BACKGROUND

Sevoflurane and isoflurane had been reported to improve ischemia/reperfusion injury (I/R) through amelioration of the inflammatory response. We aimed to explore and compare the molecular mechanisms involved in sevoflurane and isoflurane anesthesia in liver ischemia-reperfusion of rat model.

METHODS

Forty male Wistar rats were randomly divided into 4 groups: sham group, I/R group, sevoflurane group, and isoflurane group. The liver I/R injury model was established to investigate the effect of sevoflurane and isoflurane anesthesia on liver ischemia/reperfusion. The inflammatory markers and complement C3, C5a, and C6 were detected by enzyme-linked immunosorbent assay. Oxidative stress was detected by measuring the levels of malondialdehyde (MDA), superoxide dismutase (SOD), and nitric oxide (NO).

RESULTS

Our results showed that sevoflurane anesthesia significantly decreased alanine transaminase, aspartate transaminase, and lactate dehydrogenase levels compared with isoflurane and controls. Sevoflurane inhibited I/R injury induced production of tumor necrosis factor α, interleukin 1, interleukin 6, and intercellular cell adhesion molecule-1 and promoted interleukin 10 production more significantly compared with isoflurane. Reduced MDA and NO and elevated SOD release suggested that oxidative stress was attenuated by sevoflurane and isoflurane anesthesia. Both sevoflurane and isoflurane anesthesia significantly decreased plasma C3 levels compared with the I/R injury group without differences.

CONCLUSION

Sevoflurane anesthesia produced a more significant inhibitive effect on inflammatory cytokines and oxidative stress in liver I/R injury model than isoflurane, suggesting that sevoflurane is more suitable in surgery.

The effect of anesthetic preconditioning with sevoflurane on intracellular signal-transduction pathways and apoptosis, in a lung autotransplant experimental model

Background

Anesthetic pre-conditioning attenuates inflammatory response during ischemia-reperfusion lung injury. The molecular mechanisms to explain it are not fully understood. The aim of our investigation was to analyze the molecular mechanism that explain the anti-inflammatory effects of anesthetic pre-conditioning with sevoflurane focusing on its effects on MAPKs (mitogen-activated protein kinases), NF-κB (nuclear factor kappa beta) pathways, and apoptosis in an experimental lung autotransplant model.

Methods

Twenty large white pigs undergoing pneumonectomy plus lung autotransplant were divided into two 10-member groups on the basis of the anesthetic received (propofol or sevoflurane). Anesthetic pre-conditioning group received sevoflurane 3% after anesthesia induction and it stopped when one-lung ventilation get started. Control group did not receive sevoflurane in any moment during the whole study period. Intracellular signal-transduction pathways (MAPK family), transcription factor (NF-κB), and apoptosis (caspases 3 and 9) were analyzed during experiment.

Results

Pigs that received anesthetic pre-conditioning with sevoflurane have shown significant lower values of MAPK-p38, MAPK-P-p38, JNK (c-Jun N-terminal kinases), NF-κB p50 intranuclear, and caspases (p < 0.05) than pigs anesthetized with intravenous propofol.

Conclusions

Lung protection of anesthetic pre-conditioning with sevoflurane during experimental lung autotransplant is, at least, partially associated with MAPKs and NF κB pathways attenuation, and antiapoptotic effects.

[The effect of anesthetic preconditioning with sevoflurane on intracellular signal-transduction pathways and apoptosis, in a lung autotransplant experimental model]

BACKGROUND

Anesthetic pre-conditioning attenuates inflammatory response during ischemia-reperfusion lung injury. The molecular mechanisms to explain it are not fully understood. The aim of our investigation was to analyze the molecular mechanism that explain the anti-inflammatory effects of anesthetic pre-conditioning with sevoflurane focusing on its effects on MAPKs (mitogen-activated protein kinases), NF-κB (nuclear factor kappa beta) pathways, and apoptosis in an experimental lung autotransplant model.

METHODS

Twenty large white pigs undergoing pneumonectomy plus lung autotransplant were divided into two 10-member groups on the basis of the anesthetic received (propofol or sevoflurane). Anesthetic pre-conditioning group received sevoflurane 3% after anesthesia induction and it stopped when one-lung ventilation get started. Control group did not receive sevoflurane in any moment during the whole study period. Intracellular signal-transduction pathways (MAPK family), transcription factor (NF-κB), and apoptosis (caspases 3 and 9) were analyzed during experiment.

RESULTS

Pigs that received anesthetic pre-conditioning with sevoflurane have shown significant lower values of MAPK-p38, MAPK-P-p38, JNK (c-Jun N-terminal kinases), NF-κB p50 intranuclear, and caspases (p<0.05) than pigs anesthetized with intravenous propofol.

CONCLUSIONS

Lung protection of anesthetic pre-conditioning with sevoflurane during experimental lung autotransplant is, at least, partially associated with MAPKs and NF κB pathways attenuation, and antiapoptotic effects.

Ischemic Preconditioning Produces Comparable Protection Against Hepatic Ischemia/Reperfusion Injury Under Isoflurane and Sevoflurane Anesthesia in Rats

BACKGROUND

Various volatile anesthetics and ischemic preconditioning (IP) have been demonstrated to exert protective effect against ischemia/reperfusion (I/R) injury in liver. We aimed to determine whether application of IP under isoflurane and sevoflurane anesthesia would confer protection against hepatic I/R injury in rats.

METHODS

Thirty-eight rats weighing 270 to 300 grams were randomly divided into 2 groups: isoflurane (1.5%) and sevoflurane (2.5%) anesthesia groups. Each group was subdivided into sham (n = 3), non-IP (n = 8; 45 minutes of hepatic ischemia), and IP (n = 8, IP consisting of 10-minute ischemia plus 15-minute reperfusion before prolonged ischemia) groups. The degree of hepatic injury and expressions of B-cell lymphoma 2 (Bcl-2) and caspase 3 were compared at 2 hours after reperfusion.

RESULTS

Hepatic ischemia induced significant degree of I/R injuries in both isoflurane and sevoflurane non-IP groups. In both anesthetic groups, introduction of IP dramatically attenuated I/R injuries as marked by significantly lower aspartate aminotransferase and aminotransferase levels and better histologic grades compared with corresponding non-IP groups. There were 2.3- and 1.7-fold increases in Bcl-2 mRNA levels in isoflurane and sevoflurane IP groups, respectively, compared with corresponding non-IP groups (both P < .05). Caspase 3 level was significantly high in the isoflurane non-IP group compared with the sham group; however, there were no differences among the sevoflurane groups.

CONCLUSIONS

The degree of hepatic I/R injury was significantly high in both isoflurane and sevoflurane groups in rats. However, application of IP significantly protected against I/R injury in both volatile anesthetic groups to similar degrees, and upregulation of Bcl-2 might be an important mechanism.

Adenosine Receptor Adora2b Plays a Mechanistic Role in the Protective Effect of the Volatile Anesthetic Sevoflurane during Liver Ischemia/Reperfusion

Background

Liver ischemia/reperfusion (IR) injury is characterized by hepatic tissue damage and an inflammatory response. This is accompanied by the formation and vascular sequestration of platelet–neutrophil conjugates (PNCs). Signaling through Adora2b adenosine receptors can provide liver protection. Volatile anesthetics may interact with adenosine receptors. This study investigates potential antiinflammatory effects of the volatile anesthetic sevoflurane during liver IR.

Methods

Experiments were performed ex vivo with human blood and in a liver IR model with wild-type, Adora2a−/−, and Adora2b−/− mice. The effect of sevoflurane on platelet activation, PNC formation and sequestration, cytokine release, and liver damage (alanine aminotransferase release) was analyzed using flow cytometry, luminometry, and immunofluorescence. Adenosine receptor expression in liver tissue was analyzed using immunohistochemistry and real-time polymerase chain reaction.

Results

Ex vivo experiments indicate that sevoflurane inhibits platelet and leukocyte activation (n = 5). During liver IR, sevoflurane (2 Vol%) decreased PNC formation 2.4-fold in wild-type (P &lt; 0.05) but not in Adora2b−/− mice (n ≥ 5). Sevoflurane reduced PNC sequestration 1.9-fold (P &lt; 0.05) and alanine aminotransferase release 3.5-fold (P &lt; 0.05) in wild-type but not in Adora2b−/− mice (n = 5). In Adora2a−/− mice, sevoflurane also inhibited PNC formation and cytokine release. Sevoflurane diminished cytokine release (n ≥ 3) and increased Adora2b transcription and expression in liver tissue of wild-types (n = 4).

Conclusions

Our experiments highlight antiinflammatory and tissue-protective properties of sevoflurane during liver IR and reveal a mechanistic role of Adora2b in sevoflurane-associated effects. The targeted use of sevoflurane not only as an anesthetic but also to prevent IR damage is a promising approach in the treatment of critically ill patients.

Propofol but not sevoflurane prevents mitochondrial dysfunction and oxidative stress by limiting HIF-1α activation in hepatic ischemia/reperfusion injury

Mitochondrial dysfunction, reactive oxygen species (ROS) production and oxidative stress during reperfusion are determinant in hepatic ischemia/reperfusion (I/R) injury but may be impacted by different anesthetic agents. Thus, we aimed at comparing the effects of inhaled sevoflurane or intravenous propofol anesthesia on liver mitochondria in a rodent model of hepatic I/R injury. To this, male Wistar rats underwent I/R surgery using sevoflurane or propofol. In the I/R model, propofol limited the raise in serum aminotransferase levels as compared to sevoflurane. Mitochondrial oxygen uptake, respiratory activity, membrane potential and proton leak were altered in I/R; however, this impairment was significantly prevented by propofol but not sevoflurane. In addition, differently from sevoflurane, propofol limited hepatic I/R-induced mitochondria H2O2 production rate, free radical leak and hydroxynonenal-protein adducts levels. The I/R group anesthetized with propofol also showed a better recovery of hepatic ATP homeostasis and conserved integrity of mitochondrial PTP. Moreover, hypoxia-inducible factor 1 alpha (HIF-1α) expression was limited in such group. By using a cell model of desferoxamine-dependent HIF activation, we demonstrated that propofol was able to inhibit apoptosis and mitochondrial depolarization associated to HIF-1α action. In conclusion, hepatic I/R injury induces mitochondrial dysfunction that is not prevented by inhaled sevoflurane. On the contrary, propofol reduces liver damage and mitochondrial dysfunction by preserving respiratory activity, membrane potential and energy homeostasis, and limiting free radicals production as well as PTP opening. These hepatoprotective effects may involve the inhibition of HIF-1α.

Protective effects of sevoflurane in hepatic ischemia-reperfusion injury

The endothelial glycocalyx plays a critical role in the regulation of vascular structure and functions. Previous studies have demonstrated that sevoflurane, a volatile anesthetic, can preserve the endothelial glycocalyx in heart tissues against ischemia-reperfusion injury. However, little is known about the effects of sevoflurane pretreatment on the vascular structure and functions of liver tissues following ischemia-reperfusion injury. To this end, female Sprague-Dawley rats (n = 28) were anesthetized either with ketamine (80-120 mg/kg, i.p.) or with one minimum alveolar concentration (MAC) sevoflurane (2% v/v). Following in vivo hepatic ischemia procedure, the liver was isolated and reperfusion was produced. During the period of reperfusion, liver reperfusion samples were collected, and the concentrations of heparan sulfate and syndecan-1 (Syn-1), and the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) enzymes, were measured. The morphology of hepatocytes and endothelial glycocalyx were then assessed by using the light and electron microscopies, respectively. Ischemia-reperfusion increased the release of HS and Syn-1, and elevated the levels of ALT and AST in a time-dependent manner. However, sevoflurane pretreatment reduced the release of HS and Syn-1and attenuated the levels of ALT and AST, in a time-dependent manner, as compared with ketamine pretreatment. Furthermore, sevoflurane pretreatment decreased the shedding of endothelial glycocalyx and hepatocytes necrosis. Sevoflurane pretreatment preserved the endothelial glycocalyx in the liver tissue against ischemia-reperfusion injury. The effect appears to help protect hepatocytes against ischemia-reperfusion-induced necrosis.

Protective effect of sevoflurane on hepatic ischaemia/reperfusion injury in the rat: A dose-response study

BACKGROUND

Ischaemia/reperfusion injury is a common problem in hepatic surgery. An appreciation of the role of sevoflurane dose in preconditioning and subsequent hepatoprotection against ischaemia/reperfusion injury would be useful.

OBJECTIVE

The aim of current study was to investigate the protective effect of sevoflurane preconditioning at different doses on hepatic ischaemia/reperfusion injury in rats.

DESIGN

Randomised, controlled, laboratory study.

SETTING

The Department of Anaesthesiology, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong, China.

PARTICIPANTS

Fifty male Sprague-Dawley rats weighing 200 to 250 g, randomly assigned to five groups.

INTERVENTIONS

Control group (sham surgery, no ischaemia/reperfusion), I/R group (ischaemia/reperfusion but no sevoflurane pretreatment), S1 [1 minimum alveolar concentration (MAC) = 2.4%], S2 (1.5 MAC = 3.6%) and S3 (2 MAC = 4.8%) groups with sevoflurane pretreatment, respectively, followed by 60 min ischaemia and 120 min reperfusion.

MAIN OUTCOME MEASURES

At the end of reperfusion, serum levels of alanine aminotransferase and aspartate aminotransferase as well as superoxide dismutase activity, myeloperoxidase and malondialdehyde content in the liver were determined. Histological examination of the liver was also performed.

RESULTS

Serum levels of aspartate aminotransferase and alanine aminotransferase in the sevoflurane groups were significantly reduced compared to the elevated levels seen in the I/R group (P < 0.05). In the liver, the I/R-induced increase in myeloperoxidase activity and malondialdehyde level were significantly reduced by all sevoflurane concentrations (P < 0.05). The decrease in superoxide dismutase activity induced by I/R was prevented by all sevoflurane pretreatments (P < 0.05). No significant differences between the S1, S2 and S3 groups were seen in any of the above variables.

CONCLUSION

Sevoflurane pretreatment exerts a protective effect on hepatic ischaemia/reperfusion injury but there is no significant dose-response relationship in the concentration range used. It is possible that a dose-response relationship might exist at lower concentrations.

Delayed hyperoxic ventilation attenuates oxygen-induced free radical accumulation during early reperfusion after global brain ischemia

To compare the effect of immediate and delayed administration of oxygen on the accumulation of free radicals in ischemia-reperfusion animal models. Thirty-two adult male Mongolian gerbils with microdialysis probes implanted in the right hippocampal CA1 were divided randomly into four groups (eight each). One group was sham-operated (Sham group) whereas the other three groups were subjected to 10 min bilateral carotid artery occlusion (BCAO). BCAO-treated animals were then subjected to the following: (a) immediate 30% O2 (near normoxia, NO group), (b) immediate 100% O2 (hyperoxia, HO group), and (c) 30% O2 for 60 min, followed by 100% O2 for 60 min (delayed hyperoxia, DHO group). Hippocampal accumulation of hydroxyl radicals (•OH) during reperfusion was estimated by measuring 2,3-dihydroxybenzoic acid (DHBA) and 2,5-DHBA in microdialysis perfusate. Hippocampi were removed 2 h after perfusion to measure malondialdehyde, pyruvate dehydrogenase activity, indices of lipid peroxidation, and cellular respiration. At 24 h after BCAO, the histology of hippocampi was analyzed to rate the injury. Immediately after the onset of reperfusion, all groups showed markedly elevated DHBA, which returned to baseline over 1-2 h. Compared with the NO group, the HO group showed significantly higher peak DHBA and slower recovery. In contrast, the DHO group was not significantly different from the NO group in terms of the DHBA level. DHO animals also showed significantly lower hippocampal malondialdehyde accumulation and higher pyruvate dehydrogenase activity at 2 h after reperfusion versus the HO group. Histology analysis also showed animals in the DHO group with ameliorated injury compared with the HO group. Hydroxyl radical accumulation was more sensitive to O2 during early reperfusion. Delayed hyperoxia may re-establish oxidative metabolism while minimizing oxidative stress after CA.

The influence of pharmacological preconditioning with sevoflurane on incidence of early allograft dysfunction in liver transplant recipients

Background. Pharmacological preconditioning is one of the tools used to diminish preservation injury. We investigated the influence of sevoflurane preconditioning of liver grafts on postoperative graft function. Methods. Consecutive 60 deceased brain donors were randomized into sevoflurane group or control group. In sevoflurane group donors were treated with endexpiratory 2,0 volume% of sevoflurane during procurement. Primary endpoint was postoperative liver injury. Secondary endpoint was incidence of early allograft dysfunction (EAD). Results. The groups were not different in median DRI, donor age, graft steatosis, and MELD score. Peak AST and ALT levels were lower in sevoflurane group than in control group: 792 and 1861 (P = 0, 038) for AST and 606 and 1191 for ALT (P = 0, 117). Incidence of EAD was 16,7% in sevoflurane group and 50% in control group (Fisher test, P = 0, 013). In subgroups without steatosis preconditioning with sevoflurane did not have influence on incidence of EAD. In subgroups with mild and moderate steatosis incidence of EAD was lower in recipients of liver grafts treated with sevoflurane. Conclusions. Preconditioning with sevoflurane during organ procurement improves graft function by lowering incidence of early allograft dysfunction, particularly in recipients of steatotic liver grafts.

[Ischaemic and pharmacologic preconditioning: desflurane reduces renal reperfusion injury in rabbits]

BACKGROUND

Anaesthetic preconditioning, i.e. administration of volatile agents before ischemia, is known to have protective effects on several organs, but remains uncertain on the kidney. We developed a rabbit model for acute ischaemia-reperfusion injury, and examined a possible protective effect of desflurane preconditioning on the kidney.

METHODS

Forty New Zealand male rabbits, 3 months old, weighing 2-3 kg, were anaesthetized by titrated intramuscular injections of xylazine-ketamine, mechanically ventilated and monitored. They were randomly assigned into four groups: group ischaemia (I), group ischaemic preconditioning (IPC), group desflurane preconditioning (DPC), and group SHAM (S). Groups I, IPC and DPC were subjected to 45 minutes of bilateral renal ischaemia followed by 3 hours reperfusion. Group IPC was subjected to 3 x 3 minutes ischaemia, 5 minutes before the 45-minute clamping period. Group DPC was administered one MAC desflurane for 30 minutes, before a 30-minute wash-out period. Histological analysis of the cortical zone of both kidneys were blindly performed. Tubular cell damage was graded from 1 (no lesion) to 4 (>50 % cell necrosis). Pycnotic nuclei and intratubular hyaline casts were counted on each section.

RESULTS

DPC (1[1-2]) and S (1[1-1]) groups displayed lower histological grades than group 1(4[3-4]) (p<0.01); IPC had a grade of 3 (2-3), I and IPC groups had higher scores of pycnotic nuclei and hyaline casts than DPC and S.

CONCLUSION

Desflurane preconditioning was associated with a diminution of tubular cell damage. Ischaemic preconditioning did not show a significant renal protective effect.

A comparison of liver function after hepatectomy with inflow occlusion between sevoflurane and propofol anesthesia

BACKGROUND

In this study, we compared liver function tests after hepatectomy with inflow occlusion as a function of propofol versus sevoflurane anesthesia.

METHODS

One hundred patients undergoing elective liver resection with inflow occlusion were randomized into a sevoflurane group or a propofol group. General anesthesia was induced with 3 μg/kg fentanyl, 0.2 mg/kg cisatracurium, and target-controlled infusion of propofol, set at a plasma target concentration of 4 to 6 μg/mL, or sevoflurane initially started at 8%. Anesthesia was maintained with target-controlled infusion of propofol (2-4 μg/mL) or sevoflurane (1.5%-2.5%). The primary end point was postoperative liver injury assessed by peak values of liver transaminases.

RESULTS

Transaminase levels peaked between the first and the third postoperative day. Peak alanine aminotransferase was 504 and 571 U/L in the sevoflurane group and the propofol group, respectively. Peak aspartate aminotransferase was 435 U/L after sevoflurane and 581 U/L in the propofol group. There were no significant differences in peak alanine aminotransferase or peak aspartate aminotransferase between groups. Other liver function tests including bilirubin and alkaline phosphatase, and peak values of white blood cell counts and creatinine, were also not different between groups.

CONCLUSIONS

Sevoflurane and propofol anesthetics resulted in similar patterns of liver function tests after hepatectomy with inflow occlusion. These data suggest that the 2 anesthetics are equivalent in this clinical context.

Hepatic energy metabolism and the differential protective effects of sevoflurane and isoflurane anesthesia in a rat hepatic ischemia-reperfusion injury model

BACKGROUND

We investigated the effects of isoflurane and sevoflurane in a warm liver ischemia-reperfusion (IR) model on cytokines, hepatic tissue blood flow (HTBF), energy content, and liver structure.

METHODS

Seventy-two Wistar rats were randomly assigned into 1 of 3 groups: Control group, no volatile anesthetics; sevoflurane group, 2% sevoflurane; isoflurane group, 1.5% isoflurane. Thirty minutes after the start of volatile anesthetics, rats were subjected to 45 min hepatic ischemia and 2 and 4 h of reperfusion. Rats were killed at the end of ischemia, 2 and 4 h of reperfusion. Aspartate aminotransferase and alanine aminotransferase, HTBF, malondialdehyde, tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, energy charge, and histologic examination were used to evaluate the extent of liver injury.

RESULTS

Serum alanine aminotransferase and aspartate aminotransferase levels were similar in control and isoflurane groups while there was a significant decrease in the sevoflurane group in the postischemic period (P < 0.01). HTBF was remarkably better in the sevoflurane group than in the isoflurane group and worse in the control group. Tissue malondialdehyde levels were significantly low in the sevoflurane group compared with the isoflurane group at 2 h of reperfusion (P < 0.05) and reached its maximum value in the postischemic period in the control group. After ischemia, 2 and 4 h of reperfusion, tumor necrosis factor-alpha and interleukin-1beta values were lowest in the sevoflurane group and highest in the control group but it was not statistically significant (P > 0.05). In the sevoflurane group, hepatic adenosine triphosphate and energy charge were significantly high at all measurement times. At the postischemic period, energy charge was lower compared with the sevoflurane and isoflurane groups. The degree of hepatocyte injury was small in the sevoflurane group.

CONCLUSIONS

Clinically relevant concentrations of sevoflurane given before, during, and after hepatic ischemia protected the liver against IR injury, whereas the effects of isoflurane on hepatic IR injury were not notable.

Preconditioning and protection against ischaemia-reperfusion in non-cardiac organs: a place for volatile anaesthetics?

There is an increasing body of evidence that volatile anaesthetics protect myocardium against ischaemic insult by a mechanism termed 'anaesthetic preconditioning'. Anaesthetic preconditioning and ischaemic preconditioning share several common mechanisms of action. Since ischaemic preconditioning has been demonstrated in organs other than the heart, anaesthetic preconditioning might also apply in these organs and have significant clinical applications in surgical procedures carrying a high risk of ischaemia-reperfusion injury. After a brief review on myocardial preconditioning, experimental and clinical data on preconditioning in non-cardiac tissues will be presented. Potential benefits of anaesthetic preconditioning during non-cardiac surgery will be addressed.

Isoflurane improves survival and protects against renal and hepatic injury in murine septic peritonitis

We have demonstrated that volatile anesthetics reduce inflammation after renal ischemia/reperfusion injury in vivo. As hyperactive uncontrolled inflammation can lead to mortality and morbidity during early sepsis, we questioned whether the volatile anesthetic isoflurane could reduce mortality and protect against sepsis induced renal and hepatic dysfunction. Mice were anesthetized with isoflurane or with pentobarbital and subjected to cecal ligation and puncture (CLP) to induce septic peritonitis. Mice were anesthetized for an additional 3 h after CLP with either isoflurane or pentobarbital. Renal and hepatic function was assessed 24 h later and survival after CLP was assessed for 7 days. To determine if isoflurane protects by reducing inflammation, we quantified renal tubular expression of pro-inflammatory (intercellular adhesion molecule 1, tumor necrosis factor alpha [TNF-alpha], and interleukin [IL] 1beta) messenger RNA with reverse transcriptase-polymerase chain reaction. We also measured the plasma levels of the pro-inflammatory cytokines TNF-alpha, keratinocyte-derived chemokine (KC), and IL-6 and an anti-inflammatory cytokine IL-10. Renal cortical apoptosis was also assessed 24 h after CLP. Twenty-four hours after the septic insult, isoflurane-treated mice had significantly improved renal and hepatic function compared with mice anesthetized with pentobarbital. Renal cortices of isoflurane-treated mice had significantly reduced expression of intercellular adhesion molecule 1, TNF-alpha, and IL-1beta messenger RNA and showed less apoptosis. Isoflurane-treated mice had lower plasma levels of TNF-alpha, KC, and IL-6. Isoflurane-anesthetized mice also had significantly prolonged and increased survival compared with pentobarbital-anesthetized mice. Therefore, isoflurane anesthesia conferred significant protection against renal and hepatic dysfunction and death after septic peritonitis and attenuated renal inflammation and apoptosis compared with pentobarbital anesthesia.

Effects of sevoflurane and propofol on ischaemia–reperfusion injury after thoracic-aortic occlusion in pigs

BACKGROUND

Thoraco-abdominal-aneurysm surgery predicts high mortality. Propofol and sevoflurane are commonly used anaesthetics for this procedure. Halogenated anaesthetics induce organ protection similar to ischaemic preconditioning. We investigated which anaesthetic regimen would lead to a better protection against ischaemia-reperfusion injury induced by temporary thoracic-aortic occlusion.

METHODS

Following initial fentanyl-midazolam anaesthesia for surgical preparation, 18 pigs were randomly assigned to two groups: group one received propofol (n=9) and group two sevoflurane (n=9) before, during, and after lower body ischaemia in an investigator blinded fashion. Ten animals without aortic occlusion served as time controls (propofol, n=5; sevoflurane, n=5). For induction of ischaemia, the thoracic aorta was occluded by a balloon-catheter for 90 min. After 120 min of reperfusion, the study anaesthetics were discontinued and fentanyl-midazolam re-established for an additional 180 min. Goal-directed therapy was performed during reperfusion. Fluid and catecholamine requirements were assessed. Serum samples and intestinal tissue specimens were obtained.

RESULTS

Severe declamping shock occurred in both study groups. While norepinephrine requirements in the sevoflurane group were significantly reduced during reperfusion (P<0.05), allowing cessation of catecholamine support in 4/9 animals, all 9/9 animals were still catecholamine dependent at the end of the experiment in the propofol group. Serum activities of lactate dehydrogenase, aspartate transaminase, and alanine aminotransferase were lower with sevoflurane (P<0.05). Small intestine tissue specimens did not differ histologically.

CONCLUSIONS

Use of sevoflurane compared with propofol attenuated the haemodynamic sequelae of reperfusion injury in our model. Release of serum markers of cellular injury was also attenuated.

Cardioprotection by volatile anesthetics: new applications for old drugs?

PURPOSE OF REVIEW

Pharmacological interventions may play a prominent role in reducing organ damage in response to physiologic stress. A growing body of evidence indicates that volatile anesthetics exert protective effects against ischemia-reperfusion injury in vivo. Administration of volatile anesthetics before prolonged coronary artery occlusion and reperfusion has been shown to produce cardioprotection, a phenomenon termed anesthetic-induced preconditioning. Endogenous signal transduction proteins, reactive oxygen species, mitochondria, and ion channels have been implicated in anesthetic-induced preconditioning, and new data regarding the triggering and effector roles for these various components have been discovered that advance our understanding of the mechanisms responsible for anesthetic-induced preconditioning. This review will update and integrate these recent data into the current mechanistic model of anesthetic-induced preconditioning.

RECENT FINDINGS

Despite a wealth of data from animal studies, the mechanism by which preconditioning with volatile anesthetics alleviates ischemic injury remains incompletely understood. Recent data have identified important interactions between reactive oxygen species and key intracellular signal transduction enzymes and proteins implicated in anesthetic-induced preconditioning.

SUMMARY

This review highlights the major recent findings examining mechanisms of volatile anesthetic cardioprotection.

Cardioprotection with volatile anesthetics: mechanisms and clinical implications

Cardiac surgery and some noncardiac procedures are associated with a significant risk of perioperative cardiac morbid events. Experimental data indicate that clinical concentrations of volatile general anesthetics protect the myocardium from ischemia and reperfusion injury, as shown by decreased infarct size and a more rapid recovery of contractile function on reperfusion. These anesthetics may also mediate protective effects in other organs, such as the brain and kidney. Recently, a number of reports have indicated that these experimentally observed protective effects may also have clinical implications in cardiac surgery. However, the impact of the use of volatile anesthetics on outcome measures, such as postoperative mortality and recovery in cardiac and noncardiac surgery, is yet to be determined.

Hepatic function during xenon anesthesia in pigs

BACKGROUND

Inhalation anesthetics decrease liver perfusion and oxygen consumption by changing the distribution pattern of perfusion between the hepatic artery and the portal vein and by direct effects on liver cells. The effects of xenon on liver perfusion and function have been not investigated until now.

METHODS

Fourteen pigs were randomly assigned to two groups to receive either 73-78% xenon or 75% nitrogen in oxygen with additional supplementation of pentobarbital and buprenorphine. Microspheres were used to determine the arterial perfusion of the liver and splanchnic organs. Oxygen contents were measured by catheterization of the portal and a liver vein. Lactate and glucose plasma concentrations were measured in hepatic, mixed venous and arterial blood. Alanine aminotransferase (ALT) and lactate dehydrogenase (LOH) plasma concentrations were measured in arterial blood. Urea production rates were calculated to assess hepatic metabolic function.

RESULTS

Significant higher oxygen contents were found in the liver venous blood during xenon anesthesia. No differences were found in any other investigated parameters.

CONCLUSION

Higher oxygen content in liver venous blood observed during xenon anesthesia was not induced by changes in hepatic perfusion distribution or by an impairment of liver metabolic capacity. However, it can be explained by similar results known from inhalation anesthesia. Additionally, the effect can be caused by the reduction of plasma catecholamine concentrations during xenon anesthesia.

Hepatobiliary scintigraphy for evaluating the hepatotoxic effect of halothane and the protective effect of catechin in comparison with histo-chemical analysis of liver tissue

Halothane and its metabolites cause liver damage by decreasing liver blood flow and generating free-radical species. Catechin suppresses lipid peroxidation and increases enzyme activity, therefore it seems to be capable of protecting liver parenchyma against the direct toxic effect of halothane. The aim of this study was to investigate the role of hepatobiliary scintigraphy in detecting liver damage after halothane anaesthesia and the protective effect of catechin in comparison with histo-chemical analysis. Thirty rabbits, divided into three groups (A, controls; B, halothane; and C, catechin+halothane), were investigated. In group A no anaesthesia was administered. Group B only received halothane, while group C was pretreated with catechin and halothane anaesthesia was administered for 2 h. Dynamic scintigrams were taken for 60 min after injecting 99mTc-mebrofenin, and the time of peak uptake (TPU) and the time for half of the activity to clear from the liver (T(1/2)) were calculated. Rabbits were killed, and malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) levels were measured in hepatic tissue. The TPU and T(1/2) values of group A is significantly lower than in groups B and C (P<0.0002 and P<0.0002, respectively, for TPU; and P<0.0002 and P<0.0003, respectively, for T(1/2)). The TPU and T(1/2) values of group B were significantly higher than in group C (P<0.0003 and P<0.0003, respectively). The hepatic MDA level of group A was significantly lower than in groups B and C (P<0.0002 and P<0.0002, respectively). SOD, GSH-Px and CAT levels of group A were significantly higher than in groups B and C (P<0.0002, P<0.0001 and P<0.003, respectively, for group A vs group B; and P<0.0005, P<0.0002 and P<0.03, respectively, for group A vs group C). The MDA level of group B was significantly higher than that in group C (P<0.0002). SOD, GSH-Px and CAT levels of group B were significantly lower than in group C (P<0.0002, P<0.0002 and P<0.003, respectively). According to these results, we suggest that catechin protects liver parenchyma against the toxic effect of halothane and its metabolites, and that, compared to invasive histo-chemical analysis, hepatobiliary scintigraphy is a useful and alternative non-invasive method for detecting the protective effect of catechin on liver parenchyma after halothane anaesthesia.

Pronounced effect of minor changes in body temperature on ischemia and reperfusion injury in rat liver

This study examined the effects of 1 degrees C hypo- or hyperthermia on in vivo liver ischemia and reperfusion (I/R) injury in 15 fasted male Wistar rats. Rats were ventilated, and rectal temperature was maintained at 36, 37 (normothermic), or 38 degrees C. In all rats, 70% liver ischemia was induced by clamping the afferent vessels to the median and left lateral lobes for 60 min, and reperfusion was allowed for 90 min. Changes in plasma aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alpha-glutathione S-transferase (alpha-GST) levels were measured, hemodynamics and bile secretion were monitored, and arterial blood-gas analysis was performed. All ventilated rats showed a normal pH, arterial PCO(2), and arterial PO(2). AST, ALT, and alpha-GST levels were significantly higher in the 38 degrees C group when compared with the 36 and 37 degrees C groups after ischemia. No differences in bile secretion were found between all groups. Histopathological alterations were in agreement with AST, ALT, and alpha-GST levels in plasma. We conclude that a decrease of only 1 degrees C in body temperature significantly attenuates liver I/R injury, whereas an increase of 1 degrees C significantly increases liver I/R injury.

The role of hepatobiliary scintigraphy in the evaluation of the protective effects of dimethylsulphoxide in ischaemic/reperfusion injury of liver

Liver ischaemia may lead to parenchymal damage depending on the duration of the ischaemia. Dimethylsulphoxide (DMSO), a well-known radical oxygen scavenger, is a protective agent against ischaemia/reperfusion injury. In this study we aimed to investigate the role of hepatobiliary scintigraphy (HBSc) in detecting the protective effect of DMSO. Eighteen rabbits, in three groups of six, were injected with 37 MBq technetium-99m-mebrofenin via the ear veins. Dynamic scintigrams were taken for 60 min (1 frame/min). In group A, HBSc was performed without any surgery. In groups B and C the Pringle manoeuvre (PM) was applied for 30 min, and tissue specimens for electron microscopy were taken from the liver parenchyma 5 min after the end of the PM. In addition, in group C 1 g/kg DMSO was injected into each rabbit 5 min before application of the PM. HBSc was then performed in groups B and C. From the dynamic images time-activity curves (TACs) were obtained for each group, and the time of peak uptake (TPU) and time for half of the activity to clear from the liver (T1/2) were calculated. The TPU and T1/2 of group B were significantly longer than those of groups A and C (P<0.0005 and P<0.005 for TPU, and P<0.0005 and P<0.02 for T1/2, respectively). The TPU and T1/2 of group C were significantly longer than those of group A (P < 0.005 and P < 0.02, respectively). While the electron microscopic images in group C showed reversible changes, those in group B showed both irreversible and reversible changes. The electron microscopic findings of groups B and C confirmed the scintigraphic findings. In conclusion, HBSc might be used as a practical quantitative method for detecting the protective effects of DMSO. However, its clinical value should be evaluated by further studies with human subjects.