Propofol attenuates ischemia-reperfusion injury in the isolated rat heart

Influence of Anesthetics on Cardiac Index and Metabolic Outcomes in Mitral and Aortic Valve Replacement in Adults: A Randomized Clinical Study

Background

Cardiac index (CI) and metabolic response to surgery are important indicators of the course of the intraoperative period.

Objectives

This study aimed to determine the effect of sevoflurane, isoflurane, and propofol on CI and metabolic outcomes during aortic and mitral valve replacement in adults.

Methods

In this single-center prospective randomized controlled clinical study, a total of 75 patients were randomly assigned into 3 groups according to the type of anesthesia: The propofol group (n = 25), the sevoflurane group (n = 25), and the isoflurane group (n = 25). Cardiac stroke volume (SV) was determined by intraesophageal echocardiography (SV = end-diastolic volume - end-systolic volume). Cardiac output (CO) and CI were calculated according to the formulas. Oxygen consumption during surgery = CI × arteriovenous difference. Indirect calorimetry was used to determine energy expenditure during anesthesia using a spirometry device.

Results

The use of anesthetics did not change CI. Cardiac index decreased from 3 to 2.9 L/min/m2 in the propofol group, increased from 3.1 to 3.2 L/min/m2 in the sevoflurane group, and decreased from 2.9 to 2.7 L/min/m2 in the isoflurane group. Compared to inhaled anesthetics, propofol significantly reduced VO2 from 179.1 to 135.7 mL/min/m2. Propofol reduced energy expenditure from 1483.7 to 1333.5 kcal.

Conclusions

Volatile anesthetics, propofol has practically no effect on CI in an uncomplicated surgery. Anesthesia with propofol is associated with lower VO2 and better oxygen delivery to tissues. Energy consumption during propofol anesthesia decreases.

Propofol inhibits oxidative stress injury through the glycogen synthase kinase 3 beta/nuclear factor erythroid 2-related factor 2/heme oxygenase-1 signaling pathway

Oxidative stress is the main cause of ischemia/reperfusion injury. Propofol is a commonly used intravenous hypnotic anesthetic agent with antioxidant properties. In this study, we aimed to elucidate the protective effects of propofol on H2O2-induced cardiomyocyte injury and myocardial ischemic/reperfusion injury (MIRI) in rats. Cardiomyocyte injury was evaluated by determining cardiac troponin-1 (cTn-1) and creatine kinase-MB (CK-MB) levels. Antioxidative stress was assessed by measuring lactate dehydrogenase (LDH), malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), reactive oxygen species (ROS), and catalase (CAT) levels. Apoptosis was evaluated using flow cytometry and TUNEL assays. Bax and Bcl-2 expression levels were determined by quantitative reverse transcription PCR (qRT-PCR) and Western blotting. The levels of glycogen synthase kinase 3 beta/nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway-related factors were measured using Western blotting. Myocardial infarction in rats was analyzed using an Evans blue staining assay. The results showed that propofol reduced the levels of CK-MB, cTn-1, LDH, MDA, and ROS, and increased the levels of GSH, SOD, and CAT in H2O2-treated H9c2 cells. Additionally, propofol inhibited H2O2-induced apoptosis by downregulating Bax and upregulating Bcl-2. Moreover, propofol decreased the area of myocardial infarction in rats with MIRI. The GSK3β-Nrf2/HO-1 signaling pathway was activated by propofol. Rescue experiments showed that Nrf2 knockdown alleviated the effects of propofol on oxidative stress and apoptosis in H9c2 cells. In conclusion, propofol attenuated H2O2-induced myocardial cell injury by regulating the GSK3β/Nrf2/HO-1 signaling pathway and alleviating MIRI, suggesting that propofol is a promising therapeutic option for ischemic heart disease.

Gene-gene interactions in the protein kinase C/endothelial nitric oxide synthase axis impact the hypotensive effects of propofol

Anaesthesia with propofol is frequently associated with hypotension, which is at least partially attributable to increased nitric oxide (NO) formation derived from the activation of protein kinase C (PKC)/endothelial NO synthase (NOS3) axis. In this cross-sectional study, we tested whether PRKCA (which encodes PKCα) polymorphisms, or haplotypes, and interactions among PRKCA and NOS3 polymorphisms affect the hypotensive responses to propofol. We collected venous blood samples from 164 patients before and 10 min after propofol administration. Genotypes were determined by PCR and haplotype frequencies were estimated. Nitrite and NO_x (nitrites+nitrates) levels were measured by using an ozone-based chemiluminescence assay and the Griess reaction, respectively. We used multifactor dimensionality reduction to test interactions among PRKCA and NOS3 polymorphisms. Propofol promoted enhanced blood pressure-lowering effects and increased nitrite levels in subjects carrying GA + AA genotypes for the rs16960228 and TC + CC genotypes for the rs1010544 PRKCA polymorphisms, and the CCG haplotype. Moreover, genotypes for the rs1010544 PRKCA polymorphism were associated with higher or lower blood pressure decreases in response to propofol depending on the genotypes for the rs2070744 NOS3 polymorphism. Our findings suggest that PRKCA genotypes and haplotypes impact the hypotensive responses to propofol, possibly by modifying NO bioavailability, and that PRKCA-NOS3 interactions modify the blood pressure-lowering effects of propofol.

Propofol Inhibits Ischemia/Reperfusion-Induced Cardiotoxicity Through the Protein Kinase C/Nuclear Factor Erythroid 2-Related Factor Pathway

Both hydrogen peroxide (H₂O₂, H) and ischemia/reperfusion (I/R) can damage cardiomyocytes, which was inhibited by propofol (P). The present research was designed to examine whether propofol can reduce myocardial I/R injury by activating protein kinase C (PKC)/nuclear factor erythroid-2-related factor 2 (NRF2) pathway in H9C2 cells and rat Langendorff models. H9C2 cells were disposed of no reagents (C), H₂O₂ for 24 h (H), propofol for 1 h before H₂O₂ (H+P), and chelerythrine (CHE, PKC inhibitor) for 1 h before propofol and H₂O₂ (H+P+CHE). N = 3. The PKC gene of H9C2 was knocked down by siRNA and overexpressed by phorbol 12-myristate 13-acetate (PMA, PKC agonist). The cell viability and the expressions of PKC, NRF2, or heme oxygenase-1(HO-1) were evaluated. Propofol significantly reduced H9C2 cell mortality induced by H₂O₂, and significantly increased NRF2 nuclear location and HO-1 expression, which were restrained by siRNA knockout of PKC and promoted by PMA. Rat hearts were treated with KrebsHenseleit solution for 120 min (C), with (I/R+P) or without (I/R) propofol for 20 min before stopping perfusion for 30 min and reperfusion for 60 min, and CHE for 10 min before treated with propofol. N = 6. The levels of lactate dehydrogenase (LDH), superoxide dismutase (SOD), and creatine kinase-MB (CK-MB) in perfusion fluid and antioxidant enzymes in the myocardium were assessed. I/R, which increased LDH and CK-MB expression and reduced SOD expression, boosted the pathological damage and infarcts of the myocardium after reperfusion. However, propofol restrained all these effects, an activity that was antagonized by CHE. The results suggest that propofol pretreatment protects against I/R injury by activating of PKC/NRF2 pathway.

Propofol Induces Cardioprotection Against Ischemia-Reperfusion Injury via Suppression of Transient Receptor Potential Vanilloid 4 Channel

Ca²⁺ entry via the transient receptor potential vanilloid 4 (TRPV4) channel contributes to Ca²⁺ overload and triggers many pathophysiological conditions, including myocardial ischemia/reperfusion (I/R) injury. Propofol, a widely used intravenous anesthetic, attenuates myocardial I/R injury. However, the mechanism of propofol remains to be examined. The present study aims to test the hypothesis that propofol attenuates myocardial I/R injury through the suppression of TRPV4. We used a murine ex vivo model of myocardial I/R and in vitro cultured myocytes subjected to hypoxia/reoxygenation (H/R). Propofol or TRPV4 antagonist, HC-067047, attenuates myocardial I/R injury in isolated hearts. In addition, propofol, HC-067047, or TRPV4-siRNA attenuates H/R-induced intracellular Ca²⁺ concentration ([Ca²⁺]_i) increase and cell viability reduction. On the contrary, TRPV4 agonist GSK1016790A exacerbates both ex vivo and in vitro myocardial injury. Pretreatment with propofol reverses the myocardial injury and intracellular Ca²⁺ overload induced by GSK1016790A at least in vitro. However, neither the combination of propofol and HC-067047 nor applying propofol to cells transfected with TRPV4-siRNA creates additional protective effects. In addition, propofol dose-dependently inhibits TRPV4-mediated Ca²⁺ entry induced by GSK1016790A and 4α-PDD. Propofol attenuates myocardial I/R injury partially through the suppression of TRPV4 channel and the subsequent inhibition of intracellular Ca²⁺ overload.

Propofol Ameliorates H9c2 Cells Apoptosis Induced by Oxygen Glucose Deprivation and Reperfusion Injury via Inhibiting High Levels of Mitochondrial Fusion and Fission

Background: The cardioprotective effect of propofol on ischemia-reperfusion injury (I/R injury) is partly due to suppressing apoptosis. Mitochondrial dynamics are also involved in apoptosis. Mitochondrial fusion and fission lead to mitochondrial morphological changes. However, whether suppressing apoptosis effect of propofol against ischemia-reperfusion injury in the heart is via regulating mitochondrial morphology remains unclear. Methods: H9c2 cells underwent oxygen glucose deprivation (OGD) followed by reperfusion to simulate cardiomyocytes ischemia/reperfusion injury. Cell viability, apoptosis ratio and intracellular reactive oxygen species (ROS) were assessed, respectively. Mitochondrial membrane dynamin family proteins, extracellular signal regulated kinase 1 and 2 (ERK1/2), phosphorylated extracellular signal regulated kinase 1 and 2 (p-ERK1/2) and proteins related to intrinsic apoptosis pathways were detected by western blotting. The mitochondrial morphology and the distribution of dynamin-related protein 1 (Drp1) were observed by using laser confocal microscopy. Results: Propofol enhanced the survival of H9c2 cells, decreased ROS levels and inhibited apoptosis during oxygen glucose deprivation/reperfusion (OGD/R) injury. Mitochondrial fission in H9c2 cells was inhibited by propofol during OGD injury. Propofol alleviated high levels of mitochondrial fusion and fission during OGD/R in H9c2 cells, by regulating mitochondrial membrane remodeling dynamin family proteins. Propofol inhibited Drp1 colocalization with mitochondria in H9c2 cells during OGD/R injury. Moreover, Drp1 phosphorylation was inhibited by propofol through decreasing ERK activation during OGD/R injury. We found that propofol ameliorated H9c2 cells apoptosis during OGD/R via inhibiting mitochondrial cytochrome c release and caspase-9, caspase-6, caspase-7 and caspase-3 activation. Conclusion: Propofol suppresses H9c2 cells apoptosis during OGD/R injury via inhibiting intrinsic apoptosis pathway, which may be partly due to reducing high levels of mitochondrial fusion and fission induced by OGD/R injury.

A randomized controlled trial comparing the myocardial protective effects of isoflurane with propofol in patients undergoing elective coronary artery bypass surgery on cardiopulmonary bypass, assessed by changes in N-terminal brain natriuretic peptide

Objective:

The objective of the study is to compare the myocardial protective effects of isoflurane with propofol in patients undergoing elective coronary artery bypass surgery on cardiopulmonary bypass (CPB), the cardio protection been assessed by changes in N-terminal brain natriuretic peptide (NT proBNP).

Methodology and Design:

This study is designed as a participant blinded, prospective randomized clinical trial.

Setting:

Christian Medical College Hospital, Vellore, India.

Participants:

Patients undergoing elective coronary artery bypass surgery on CPB.

Intervention:

Anesthesia was maintained with 0.8–1.2 end tidal concentrations of isoflurane in the isoflurane group and in the propofol group, anesthesia was maintained with propofol infusion as described by Roberts et al.

Measurements:

Hemodynamic data were recorded at frequent intervals during the surgery and up to 24 h in the Intensive Care Unit (ICU). The other variables that were measured include duration of mechanical ventilation, dose and duration of inotropes in ICU, (inotrope score), duration of ICU stay, NT proBNP levels before induction and 24 h postoperatively, creatine kinase-MB levels in the immediate postoperative, first and second day.

Results:

Mean heart rate was significantly higher in propofol group during sternotomy, (P = 0.021). Propofol group had a significantly more number of patients requiring nitroglycerine in the prebypass period (P = 0.01). The increase in NT proBNP from preoperative to postoperative value was lesser in the isoflurane group compared to propofol even though the difference was not statistically significant. The requirement of phenylephrine to maintain mean arterial pressure within 20% of baseline, mechanical ventilation duration, inotrope use, duration of ICU stay and hospital stay were found to be similar in both groups.

Conclusion:

Propofol exhibit comparable myocardial protective effect like that of isoflurane in patients undergoing coronary artery bypass graft surgery. Considering the unproven mortality benefit of isoflurane and the improved awareness of green OT concept, propofol may be the ideal alternative to volatile anesthetics, at least in patients with good left ventricular function.

Kcne2 deletion attenuates acute post-ischaemia/reperfusion myocardial infarction

AIMS

Most cardiac arrhythmia-associated genes encode ion channel subunits and regulatory proteins that are also expressed outside the heart, suggesting that diseases linked to their disruption may be multifactorial. KCNE2 is a ubiquitously expressed potassium channel β subunit associated with cardiac arrhythmia, atherosclerosis, and myocardial infarction (MI) in human populations. Here, we tested the hypothesis that Kcne2 disruption in mice would influence the acute outcome of experimentally induced MI.

METHODS AND RESULTS

One-year-old male Kcne2⁺/⁺ and Kcne2⁻/⁻ mice were subjected to cardiac ischaemia/reperfusion injury (IRI) by left anterior descending coronary artery ligation. After reperfusion (3 h), infarct size and markers of tissue damage were quantified. Unexpectedly, post-reperfusion, Kcne2⁻/⁻ mice exhibited 40% lower infarct size, decreased myocardial apoptosis and damage, and more than two-fold lower serum levels of damage markers, lactate dehydrogenase and creatine kinase, than Kcne2⁺/⁺ mice. Kcne2 deletion, despite increasing normalized heart weight and prolonging baseline QTc by 70%, helped preserve post-infarct cardiac function (quantified by a Millar catheter), with parameters including left ventricular maximum pressure, max dP/dt (P < 0.01), contractility index, and pressure/time index (P < 0.05) all greater in Kcne2⁻/⁻ compared with Kcne2⁺/⁺ mice. Western blotting indicated two-fold-increased glycogen synthase kinase 3β (GSK-3β) phosphorylation (inactivation) before and after IRI (P < 0.05) in Kcne2⁻/⁻ mice compared with Kcne2⁺/⁺ mice. GSK-3β inhibition by SB216763 mimicked in Kcne2⁺/⁺ mice the cardioprotective effects of Kcne2 deletion, but did not further enhance them in Kcne2⁻/⁻mice, suggesting that GSK-3β inactivation was a primary cardioprotective mechanism arising from Kcne2 deletion.

CONCLUSIONS

Kcne2 deletion preconditions the heart, attenuating the acute tissue damage caused by an imposed IRI. The findings contribute further evidence that genetic disruption of arrhythmia-associated ion channel genes has cardiac ramifications beyond abnormal electrical activity.

Mitochondrial involvement in propofol-induced cardioprotection: An in vitro study in human myocardium

Propofol has been shown to exert cardioprotection, but the underlying mechanisms remain incompletely understood. We examined: (1) whether propofol-induced cardioprotection depended on the time and the dose of administration; (2) the role of mitochondrial adenosine triphosphate-sensitive potassium channels, nitric oxide synthase, and mitochondrial respiratory chain activity in propofol-induced cardioprotection. Human right atrial trabeculae were obtained during cardiopulmonary bypass for coronary artery bypass and aortic valve replacement. Isometric force of contraction of human right atrial trabeculae hanged in an oxygenated Tyrode's solution was recorded during 30-min hypoxia and 60-min reoxygenation (Control). Propofol 0.1, 1, and 10 µM was administered: (1) 5 min before hypoxia until the end of the experiment; (2) 5 min followed by 5-min washout before hypoxia; (3) during the reoxygenation period, propofol 10 µM was administered in presence of 5-hydroxydecanoate (antagonist of mitochondrial adenosine triphosphate-sensitive potassium channels), and NG-nitro-L-arginine methyl ester (inhibitor of nitric oxide synthase). In addition, mitochondria were isolated from human right atrial at 15 min of reoxygenation. The effect of propofol on activity of the mitochondrial respiratory chain complexes was evaluated by spectrophotometry. The force of contraction (% of baseline) and the complex activity between the different groups were compared with an analysis of variance and post hoc test. Propofol 10 µM administered during the reoxygenation period significantly improved the recovery of force of contraction at the end of reoxygenation (82 ± 6% of baseline value vs. 49 ± 6% in Control; P < 0.001). The beneficial effects of propofol 10 µM were abolished by co-administration with 5-hydroxydecanoate (53 ± 8%) or NG-nitro-L-arginine methyl ester (57 ± 6%). Propofol 10 µM significantly increased enzymatic activities of the mitochondrial respiratory chain complexes, in reoxygenation period, compared to their respective untreated controls. In conclusion, in human myocardium, propofol-induced cardioprotection was mediated by mitochondrial adenosine triphosphate-sensitive potassium channels opening, nitric oxide synthase activation and stimulation of mitochondrial respiratory chain complexes, in early reoxygenation period.

Effects of Sevoflurane and Propofol on Organ Blood Flow in Left Ventricular Assist Devices in Pigs

The aim of this study was to assess the effect of sevoflurane and propofol on organ blood flow in a porcine model with a left ventricular assist device (LVAD). Ten healthy minipigs were divided into 2 groups (5 per group) according to the anesthetic received (sevoflurane or propofol). A Biomedicus centrifugal pump was implanted. Organ blood flow (measured using colored microspheres), markers of tissue injury, and hemodynamic parameters were assessed at baseline (pump off) and after 30 minutes of partial support. Blood flow was significantly higher in the brain (both frontal lobes), heart (both ventricles), and liver after 30 minutes in the sevoflurane group, although no significant differences were recorded for the lung, kidney, or ileum. Serum levels of alanine aminotransferase and total bilirubin were significantly higher after 30 minutes in the propofol group, although no significant differences were detected between the groups for other parameters of liver function, kidney function, or lactic acid levels. The hemodynamic parameters were similar in both groups. We demonstrated that, compared with propofol, sevoflurane increases blood flow in the brain, liver, and heart after implantation of an LVAD under conditions of partial support.

Attenuation of cisplathin-induced toxic oxidative stress by propofol

Background:

Antioxidant effects of propofol (2, 6-diisopropylphenol) were evaluated against cisplatin-i‎nduced oxidative stress in rat.

Objectives:

In this experimental study, 20 male rats were equally divided into 4 groups (5 rats each), and were treated by propofol (10 mg/kg/day, IP), or cisplatin (7 mg /kg/day, IP), or both.

Materials and Methods:

G‎roup one was control, while group 2 was given cisplatin (7 mg /kg/day, IP). Animals of the third group received only propofol (10 mg/kg/day, IP). Group 4 was given propofol with cisplatin once per day for 7 days. After treatment, blood urea nitrogen, creatinine levels, and oxidative stress m‎arkers such as total thiol groups (TTG), lipid peroxidation (LPO), and total antioxidant ‎capacity (TAC) were measured.

Results:

Oxidative stress induced by cisplatin, was evident by a significant increase in LPO and decrease in TTG and TAC. Propofol recovered ‎cisplatin -induced changes in TAC, TTG and LPO in blood.

Conclusions:

It is concluded that oxidative ‎damage is the mechanism of cisplatin toxicity, which can be recovered by propofol.‎

The effects of propofol cardioplegia on blood and myocardial biomarkers of stress and injury in patients with isolated coronary artery bypass grafting or aortic valve replacement using cardiopulmonary bypass: protocol for a single-center randomized controlled trial

Background

Despite improved myocardial protection strategies, cardioplegic arrest and ischemia still result in reperfusion injury. We have previously published a study describing the effects of propofol (an anesthetic agent commonly used in cardiac surgery) on metabolic stress, cardiac function, and injury in a clinically relevant animal model. We concluded that cardioplegia supplementation with propofol at a concentration relevant to the human clinical setting resulted in improved hemodynamic function, reduced oxidative stress, and reduced reperfusion injury when compared to standard cardioplegia.

Objective

The Propofol cardioplegia for Myocardial Protection Trial (ProMPT) aims to translate the successful animal intervention to the human clinical setting. We aim to test the hypothesis that supplementation of the cardioplegic solution with propofol will be cardioprotective for patients undergoing isolated coronary artery bypass graft or aortic valve replacement surgery with cardiopulmonary bypass.

Methods

The trial is a single-center, placebo-controlled, randomized trial with blinding of participants, health care staff, and the research team. Patients aged between 18 and 80 years undergoing nonemergency isolated coronary artery bypass graft or aortic valve replacement surgery with cardiopulmonary bypass at the Bristol Heart Institute are being invited to participate. Participants are randomly assigned in a 1:1 ratio to either cardioplegia supplementation with propofol (intervention) or cardioplegia supplementation with intralipid (placebo) using a secure, concealed, Internet-based randomization system. Randomization is stratified by operation type and minimized by diabetes mellitus status. Biomarkers of cardiac injury and metabolism are being assessed to investigate any cardioprotection conferred. The primary outcome is myocardial injury, studied by measuring myocardial troponin T. The trial is designed to test hypotheses about the superiority of the intervention within each surgical stratum. The sample size of 96 participants has been chosen to achieve 80% power to detect standardized differences of 0.5 at a significance level of 5% (2-tailed) assuming equal numbers in each surgical stratum.

Results

A total of 96 patients have been successfully recruited over a 2-year period. Results are to be published in late 2014.

Conclusions

Designing a practicable method for delivering a potentially protective dose of propofol to the heart during cardiac surgery was challenging. If our approach confirms the potential of propofol to reduce damage during cardiac surgery, we plan to design a larger multicenter trial to detect differences in clinical outcomes.

Trial Registration

International Standard Randomized Controlled Trial Number (ISRCTN): 84968882; http://www.controlled-trials.com/ISRCTN84968882/ProMPT (Archived by WebCite at http://www.webcitation.org/6Qi8A51BS).

Activation of PI3K-Akt through taurine is critical for propofol to protect rat cardiomyocytes from doxorubicin-induced toxicity

Myocardial toxicity is one of the major side effects of many chemotherapeutics. It has been shown that propofol can ameliorate the cardiotoxicity of chemotherapeutic agents. In this study, we intend to investigate the role of the PI3K-Akt-Bad signaling pathway in propofol relief of doxorubicin-induced oxidative stress and apoptosis in rat cardiomyocytes. Cultured neonatal rat cardiomyocytes were treated with vehicle, doxorubicin, propofol, or propofol plus doxorubicin in the presence or absence of the PI3K inhibitor LY294002. Cells were harvested 20 h post-exposure to doxorubicin followed by analysis of their cellular taurine content, oxidative/nitrative stresses, and cellular apoptosis. The activation of the PI3K-Akt pathway was analyzed by immunoblotting. FACS, TUNEL, and LDH assays showed that the viability of cardiomyocytes was markedly reduced by doxorubicin, but was improved by propofol. Doxorubicin treatment significantly elevated cellular reactive oxygen and nitrogen contents while lowering the levels of taurine, Akt, and phosphorylated Akt and Bad. The abovementioned doxorubicin-induced changes were reversed by propofol. The protective effects of propofol were abrogated by simultaneous treatment with LY294002. In conclusion, the PI3K-Akt-Bad pathway plays a critical role in conferring the protective effects of propofol against myocardial toxicity from doxorubicin.

Effect of HEMADO on Level of CK-MB and LDH Enzymes after Ischemia/Reperfusion Injury in Isolated Rat Heart

INTRODUCTION

Ischemia/Reperfusion (IR) injury mainly causes the increase of enzymes involved in myocytes injury including CK-MB (creatine kinase-MB) isoenzyme and LDH (lactate dehydrogenase). Leakage of CK-MB isoenzyme and LDH from myocardial tissues to blood is indicator of acute myocardial infarction. The aim of this study was to assess the effect of HEMADO on IR injury and its relationship with mitochondrial ATP-sensitive K+ channels (mitoKATP) in rat heart.

METHODS

Twenty eight male Wistar rats (250-300g) were divided into four groups (seven members in each group): control (without ischemia), I/R (with ischemia+without HEMADO), ischemia received HEMADO (HEMADO), ischemia received HEMADO and 5-HD (5-hydroxydecanoate, specific mitoKATP channel blocker) (HEMADO+5-HD). The animals were anesthetized and the hearts were quickly removed and mounted on Langendorff apparatus and perfused by Krebs-Henseleit solution under constant pressure and temperature of 37ºC. After 20 minutes of stabilization, ischemic groups were exposed to 40 minutes of global ischemia and consecutive 90 minutes of reperfusion.

RESULTS

IR injury increased the level of LDH and CK-MB in the collected coronary flow during 5 minutes since start of reperfusion. HEMADO reduced the enzymes' levels and using 5-HD abolished the effect of HEMADO.

CONCLUSION

Our findings indicated that HEMADO could protect the heart against ischemia-reperfusion injury by decreasing the CK-MB and LDH levels. The cardioprotective effect of HEMADO may be mediated in part by mitoKATP.

Effect of propofol on cardiac function and gene expression after ischemic-reperfusion in isolated rat heart

Background

The aim of this study was to examine the cardiac function and transcriptional response of the heart to propofol after ischemia-reperfusion.

Methods

Rat hearts were Langendorff-perfused using the modified Krebs-Henseleit buffer, and took 20 min stabilizing periods, 40 min ischemia periods, and then 120 min reperfusion period. The hearts were divided into 5 groups; Control: 180 min perfusion after stabilization, Ischemic: 40 min global ischemia after stabilization, followed by 120 min reperfusion, Pre: 2 µM propofol treatment was preformed only before ischemia, Post: 2 µM propofol treatment was performed only during reperfusion after ischemia, Pre/Post: 2 µM propofol treatment was performed both before and after ischemia. The measurement for cardiac performances, such as left ventricular developed pressure (LVDP), rate of left ventricular pressure generation (dP/dt), heart rate, and coronary flow were obtained. The expression profiles of isolated mRNA were determined by using Agilent microarray and real time-polymerase chain reaction (RT-PCR) was used to confirm the microarray results for a subset of genes.

Results

The Post group showed better LVDP and dP/dt than the Ischemic group. But there were no significant differences in heart rate and coronary flow among the groups. On the results of RT-PCR, the expressions of Abcc9, Bard1, and Casp4 were increased, but the expressions of Lyz, Casp8, and Timp1 were decreased in the Post group compared with the Ischemic group.

Conclusions

This study suggests that 2 µM propofol may provide cardioprotective effect, and modulate gene expression such as apoptosis, and K_ATP ion channel related-genes during reperfusion in the isolated rat hearts.

Cardioprotective effects of anesthetic preconditioning in rats with ischemia-reperfusion injury: propofol versus isoflurane

OBJECTIVE

We compare the cardioprotective effects of anesthetic preconditioning by propofol and/or isoflurane in rats with ischemia-reperfusion injury.

METHODS

Male adult Wistar rats were subjected to 60 min of anterior descending coronary artery occlusion followed by 120 min of reperfusion. Before the long ischemia, anesthetics were administered twice for 10 min followed by 5 min washout. Isoflurane was inhaled at 1 MAC (0.016) in I group, whereas propofol was inhaled intravenously at 37.5 mg/(kg(h) in P group. A combination of isoflurane and propofol was administered simultaneously in I+P group.

RESULTS

In control (without anesthetic preconditioning, C group), remarkable myocardial infarction and apoptosis accompanied by an increased level of cardiac troponin T were noted 120 min after ischemia-reperfusion. As compared to those of control group, I and P groups had comparable cardioprotection. In addition, I+P group shares with I and P groups the comparable cardioprotective effects in terms of myocardial infarction and cardiac troponin T elevation.

CONCLUSION

A combination of isoflurane and propofol produced no additional cardioprotection.

Propofol activates and allosterically modulates recombinant protein kinase C epsilon

BACKGROUND

Myocardial protection by anesthetics is known to involve activation of protein kinase C epsilon (PKC epsilon). A key step in the activation process is autophosphorylation of the enzyme at serine 729. This study's objectives were to identify the extent to which propofol interacts with PKC epsilon and to identify the molecular mechanism(s) of interaction.

METHODS

Immunoblot analysis of recombinant PKC epsilon was used to assess autophosphorylation of PKC epsilon at serine 729 before and after exposure to propofol. An enzyme-linked immunosorbant assay kit was used for measuring PKC epsilon activity. Spectral shifts in fluorescence emission maxima of the C1B subdomain of PKC epsilon in combination with the fluorescent phorbol ester, sapintoxin D, was used to identify molecular interactions between propofol and the phorbol ester/diacylglycerol binding site on the enzyme.

RESULTS

Propofol (1 microM) caused a sixfold increase in immunodetectable serine 729 phosphorylated PKC epsilon and increased catalytic activity of the enzyme in a dose-dependent manner. Dioctanoylglycerol-induced or phorbol myristic acetate-induced activation of recombinant PKC epsilon activity was enhanced by preincubation with propofol. Both propofol and phorbol myristic acetate quenched the intrinsic fluorescence spectra of the PKC epsilon C1B subdomain in a dose-dependent manner, and propofol caused a further leftward-shift in the fluorescence emission maxima of sapintoxin D after addition of the C1B subdomain.

CONCLUSIONS

These results demonstrate that propofol interacts with recombinant PKC epsilon causing autophosphorylation and activation of the enzyme. Moreover, propofol enhances phorbol ester-induced catalytic activity, suggesting that propofol binds to a region near the phorbol ester binding site allowing for allosteric modulation of PKC epsilon catalytic activity.

A unitary anesthetic binding site at high resolution

Propofol is the most widely used injectable general anesthetic. Its targets include ligand-gated ion channels such as the GABA(A) receptor, but such receptor-channel complexes remain challenging to study at atomic resolution. Until structural biology methods advance to the point of being able to deal with systems such as the GABA(A) receptor, it will be necessary to use more tractable surrogates to probe the molecular details of anesthetic recognition. We have previously shown that recognition of inhalational general anesthetics by the model protein apoferritin closely mirrors recognition by more complex and clinically relevant protein targets; here we show that apoferritin also binds propofol and related GABAergic anesthetics, and that the same binding site mediates recognition of both inhalational and injectable anesthetics. Apoferritin binding affinities for a series of propofol analogs were found to be strongly correlated with the ability to potentiate GABA responses at GABA(A) receptors, validating this model system for injectable anesthetics. High resolution x-ray crystal structures reveal that, despite the presence of hydrogen bond donors and acceptors, anesthetic recognition is mediated largely by van der Waals forces and the hydrophobic effect. Molecular dynamics simulations indicate that the ligands undergo considerable fluctuations about their equilibrium positions. Finally, apoferritin displays both structural and dynamic responses to anesthetic binding, which may mimic changes elicited by anesthetics in physiologic targets like ion channels.

Postconditioning of sevoflurane and propofol is associated with mitochondrial permeability transition pore

BACKGROUND

Sevoflurane and propofol are effective cardioprotective anaesthetic agents, though the cardioprotection of propofol has not been shown in humans. Their roles and underlying mechanisms in anesthetic postconditioning are unclear. Mitochondrial permeability transition pore (MPTP) opening is a major cause of ischemia-reperfusion injury. Here we investigated sevoflurane- and propofol-induced postconditioning and their relationship with MPTP.

METHODS

Isolated perfused rat hearts were exposed to 40 min of ischemia followed by 1 h of reperfusion. During the first 15 min of reperfusion, hearts were treated with either control buffer (CTRL group) or buffer containing 20 micromol/L atractyloside (ATR group), 3% (v/v) sevoflurane (SPC group), 50 micromol/L propofol (PPC group), or the combination of atractyloside with respective anesthetics (SPC+ATR and PPC+ATR groups). Infarct size was determined by dividing the total necrotic area of the left ventricle by the total left ventricular slice area (percent necrotic area).

RESULTS

Hearts treated with sevoflurane or propofol showed significantly better recovery of coronary flow, end-diastolic pressures, left ventricular developed pressure and derivatives compared with controls. Sevoflurane resulted in more protective alteration of hemodynamics at most time point of reperfusion than propofol. These improvements were paralleled with the reduction of lactate dehydrogenase release and the decrease of infarct size (SPC vs CTRL: (17.48+/-2.70)% vs (48.47+/-6.03)%, P<0.05; PPC vs CTRL: (35.60+/-2.10)% vs (48.47+/-6.03)%, P<0.05). SPC group had less infarct size than PPC group (SPC vs PPC: (17.48+/-2.70)% vs (35.60+/-2.10)%, P<0.05). Atractyloside coadministration attenuated or completely blocked the cardioprotective effect of postconditioning of sevoflurane and propofol.

CONCLUSION

Postconditioning of sevoflurane and propofol has cardioprotective effect against ischemia-reperfusion injury of heart, which is associated with inhibition of MPTP opening. Compared to propofol, sevoflurane provides superior protection of functional recovery and infarct size.

Myocardial protection in man--from research concept to clinical practice

Myocardial protection aims at preventing myocardial tissue loss: (a) In the acute stage, i.e., during primary angioplasty in acute myocardial infarction. In this setup, the attenuation of reperfusion injury is the main target. As a "mechanical" means, post-conditioning has already been tried in man with encouraging results. Pharmacologic interventions that could be of promise are statins, insulin, peptide hormones, including erythropoietin, fibroblast growth factor, and many others. (b) The patient with chronic coronary artery disease offers another paradigm, with the target of avoidance of further myocyte loss through apoptosis and inflammation. Various pharmacologic agents may prove useful in this context, together with exercise and "mechanical" improvement of cardiac function with attenuation of myocardial stretch, which by itself is a noxious influence. A continuous effort toward acute and chronically preserving myocardial integrity is a concept concerning both the researcher and the clinician.

Binding of propofol to blood components: implications for pharmacokinetics and for pharmacodynamics

AIMS

Propofol is a widely used i.v. anaesthetic agent. However, its binding properties to blood components have not been fully studied.

METHODS

We studied the binding of propofol to erythrocytes, to human serum and to isolated serum proteins. Because propofol bound to ultrafiltration and equilibrium dialysis membranes, we used a co-binding technique with dextran coated charcoal and with erythrocytes.

RESULTS

Propofol free fraction in blood was 1.2-1.7% at total concentrations ranging from 2.80 to 179 microM (0.5 to 32 microg ml(-1)). Fifty percent was bound to erythrocytes and 48% to serum proteins, almost exclusively to human serum albumin. In the clinical range of concentrations (0.5-16 microg ml(-1)) 40% of the molecules bound to erythrocytes are on the red blood cells membranes. No binding to lipoproteins occurred and binding to alpha1-acid glycoprotein was less than 1.5%

CONCLUSIONS

We conclude that hypoalbuminaemia may increase propofol free fraction particularly during prolonged administration. Since propofol is non-restrictively cleared, no change in clearance is expected to occur, and the increase in free fraction will not be compensated by a parallel increase in clearance. It is also noted that many in vitro studies used concentrations 50 to 500 times the concentration expected to be encountered in the immediate cellular environment.