Propofol induces a lowering of free cytosolic calcium in myocardial cells

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.

Sevoflurane exerts improved protective effects than propofol on hypoxia-reoxygenation injury by regulating the microRNA-221-5p/ADAM8 axis in cardiomyocytes

Myocardial ischemia-reperfusion (I/R) injury is a leading cause of heart disease and death. Decreasing the detrimental effect of I/R remains an urgent issue in clinical practice. The present study examined the interaction of the anesthetics (sevoflurane and propofol), ADAM8, and microRNA (miR)-221-5p in myocardial tissue protection in the hypoxia-reoxygenation (H/R) model. H9C2 cells were cultured and subjected to H/R stimulation for further verifications in vitro. Reverse transcription-quantitative PCR or western blotting was performed to evaluate mRNA or protein expression levels. Cell Counting Kit-8, BrdU, and caspase-3 activity assays were performed to investigate cell viability, proliferation and apoptosis. A dual-luciferase reporter assay was performed to verify the association between miR-221-5p and ADAM8. Sevoflurane had greater protective effects on the life of cardiomyocytes with H/R injury compared with propofol by promoting cell viability, proliferation and inhibiting apoptosis. Concurrently, compared with propofol-treated H/R injured cardiomyocytes, the expression level of ADAM8 in sevoflurane-treated H/R injured cardiomyocytes was higher. In addition, overexpression of ADAM8 promoted the cell viability and proliferation of sevoflurane-treated cardiomyocytes with H/R injury but inhibited cell apoptosis, while the downregulation of miR-221-5p showed an opposite trend to that of ADAM8 overexpression. The present data provide evidence that sevoflurane can mediate the miR-221-5p/ADAM8 axis, playing a better protective role compared with propofol in cardiomyocytes with H/R injury.

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.

Sedation After Cardiac Surgery: Is One Drug Better Than Another?

The classic high-dose narcotic-based cardiac anesthetic has been modified to facilitate a fast-track, rapid recovery in the intensive care unit (ICU). Postoperative sedation is consequently now an essential component in recovery of the patient undergoing cardiac surgery. It must facilitate the patient's unawareness of the environment as well as reduce the discomfort and anxiety caused by surgery, intubation, mechanical ventilation, suction, and physiotherapy. Benzodiazepines seem well suited for this role, but propofol, opioids, and dexmedetomidine are among other agents commonly used for sedation in the ICU. However, what is an ideal sedative for this application? When compared with benzodiazepine-based sedation regimens, nonbenzodiazepines have been associated with shorter duration of mechanical ventilation and ICU length of stay. Current sedation guidelines recommend avoiding benzodiazepine use in the ICU. However, there are no recommendations on which alternatives should be used. In postcardiac surgery patients, inotropes and vasoactive medications are often required because of the poor cardiac function. This makes sedation after cardiac surgery unique in comparison with the requirements for most other ICU patient populations. We reviewed the current literature to try to determine if 1 sedative regimen might be better than others; in particular, we compare outcomes of propofol and dexmedetomidine in postoperative sedation in the cardiac surgical ICU.

Change in Free Radical and Antioxidant Enzyme Levels in the Patients Undergoing Open Heart Surgery with Cardiopulmonary Bypass

Objective. The purpose of this study is to determine the changes in oxidative damage and antioxidant parameters in open heart surgeries with cardiopulmonary bypass (CPB) in preoperative and early postoperative periods. Methods. A total of three consecutive arterial blood samples were obtained from the patients in the study group, in preoperative, early postoperative, and postoperative periods, respectively. Oxidative damage indicator (MDA) and antioxidant indicators (GPx, GSH, CAT, and SOD) were examined. Results. A statistically significant increase was observed in MDA level in postoperative period compared to preoperative and early postoperative periods. GSH levels and CAT activities increased significantly in early postoperative and postoperative periods. Analyses revealed an increase in GPx and SOD enzyme activities only in the postoperative period. Conclusion. Even though the increase in MDA level was suppressed by the increased GSH level and CAT activity like in early postoperative period, efficiency can be brought for the increases in insufficient significant antioxidant parameters in postoperative period by administering antioxidant supplements to the patients and thus the increase in MDA in postoperative period can be significantly suppressed.

Propofol Is Cardioprotective in a Clinically Relevant Model of Normothermic Blood Cardioplegic Arrest and Cardiopulmonary Bypass

The general anesthetic propofol has been shown to be cardioprotective. However, its benefits when used in cardioplegia during cardiac surgery have not been demonstrated. In this study, we investigated the effects of propofol on metabolic stress, cardiac function, and injury in a clinically relevant model of normothermic cardioplegic arrest and cardiopulmonary bypass. Twenty anesthetized pigs, randomized to propofol treatment ( n = 8) and control ( n =12) groups, were surgically prepared for cardiopulmonary bypass (CPB) and cardioplegic arrest. Doses of warm blood cardioplegia were delivered at 15-min intervals during a 60-min aortic cross-clamped period. Propofol was continuously infused for the duration of CPB and was therefore present in blood cardioplegia. Myocardial biopsies were collected before, at the end of cardioplegic arrest, and 20 mins after the release of the aortic cross-clamp. Hemodynamic parameters were monitored and blood samples collected for cardiac troponin I measurements. Propofol infusion during CPB and before ischemia did not alter cardiac function or myocardial metabolism. Propofol treatment attenuated the changes in myocardial tissue levels of adenine nucleotides, lactate, and amino acids during ischemia and reduced cardiac troponin I release on reperfusion. Propofol treatment reduced measurable hemodynamic dysfunction after cardioplegic arrest when compared to untreated controls. In conclusion, propofol protects the heart from ischemia-reperfusion injury in a clinically relevant experimental model. Propofol may therefore be a useful adjunct to cardioplegic solutions as well as being an appropriate anesthetic for cardiac surgery.

Ischemia reperfusion injury as a modifiable therapeutic target for cardioprotection or neuroprotection in patients undergoing cardiopulmonary resuscitation

AIMS

We sought to review cellular changes that occur with reperfusion to try to understand whether ischemia-reperfusion injury (RI) is a potentially modifiable therapeutic target for cardioprotection or neuroprotection in patients undergoing cardiopulmonary resuscitation.

DATA SOURCES

Articles written in English and published in PubMed.

RESULTS

Remote ischemic conditioning (RIC) involves brief episodes of non-lethal ischemia and reperfusion applied to an organ or limb distal to the heart and brain. Induction of hypothermia involves cooling an ischemic organ or body. Both have pluripotent effects that reduce the potential harm associated with RI in the heart and brain by reduced opening of the mitochondrial permeability transition pore. Recent trials of RIC and induced hypothermia did not demonstrate these treatments to be effective. Assessment of the effect of these interventions in humans to date may have been modified by use of concurrent medications including propofol.

CONCLUSIONS

Ongoing research is necessary to assess whether reduction of RI improves patient outcomes.

Cardiopulmonary bypass and oxidative stress

The development of the cardiopulmonary bypass (CPB) revolutionized cardiac surgery and contributed immensely to improved patients outcomes. CPB is associated with the activation of different coagulation, proinflammatory, survival cascades and altered redox state. Haemolysis, ischaemia, and perfusion injury and neutrophils activation during CPB play a pivotal role in oxidative stress and the associated activation of proinflammatory and proapoptotic signalling pathways which can affect the function and recovery of multiple organs such as the myocardium, lungs, and kidneys and influence clinical outcomes. The administration of agents with antioxidant properties during surgery either intravenously or in the cardioplegia solution may reduce ROS burst and oxidative stress during CPB. Alternatively, the use of modified circuits such as minibypass can modify both proinflammatory responses and oxidative stress.

Propofol protects the immature rabbit heart against ischemia and reperfusion injury: impact on functional recovery and histopathological changes

The general anesthetic propofol protects the adult heart against ischemia and reperfusion injury; however, its efficacy has not been investigated in the immature heart. This work, for the first time, investigates the cardioprotective efficacy of propofol at clinically relevant concentrations in the immature heart. Langendorff perfused rabbit hearts (7–12 days old) were exposed to 30 minutes' global normothermic ischemia followed by 40 minutes' reperfusion. Left ventricular developed pressure (LVDP) and coronary flow were monitored throughout. Lactate release into coronary effluent was measured during reperfusion. Microscopic examinations of the myocardium were monitored at the end of reperfusion. Hearts were perfused with different propofol concentrations (1, 2, 4, and 10 μg/mL) or with cyclosporine A, prior to ischemic arrest and for 20 minutes during reperfusion. Propofol at 4 and 10 μg/mL caused a significant depression in LVDP prior to ischemia. Propofol at 2 μg/mL conferred significant and maximal protection with no protection at 10 μg/mL. This protection was associated with improved recovery in coronary flow, reduced lactate release, and preservation of cardiomyocyte ultrastructure. The efficacy of propofol at 2 μg/mL was similar to the effect of cyclosporine A. In conclusion, propofol at a clinically relevant concentration is cardioprotective in the immature heart.

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).

Propofol Protects against Ischemia/Reperfusion Injury Associated with Reduced Apoptosis in Rat Liver

Propofol is an intravenous anesthetic, reported to have a protective effect against ischemia/reperfusion (I/R) injury in heart and brain, but no definite data are available concerning its effect in hepatic I/R. This work investigated the effect of propofol anesthesia on hepatic I/R injury using in vivo rat model. Four groups of rats were included: sham operated, I/R (30 min ischemia and 2 h reperfusion), I/R treated with propofol (10 mg/kg/h), and I/R treated with propofol (20 mg/kg/h). Liver enzyme leakage, TNF-α and caspase-3 levels, and antiapoptotic Bcl-xL/apoptotic Bax gene expression, together with histopathological changes, were used to evaluate the extent of hepatic I/R injury. Compared with sham-operated group, I/R group showed significant increase in serum levels of liver enzymes (ALT, AST), TNF-α, and caspase-3 and significant decrease in the Bcl-xL/Bax ratio, associated with histopathologic damage in liver. Propofol infusion significantly attenuated these changes with reduced hepatic histopathologic lesions compared with nonpreconditioned I/R group. However, no significant differences were found between two groups treated with different doses of propofol. In conclusion, propofol infusion reduced hepatic I/R injury with decreased markers of cellular apoptosis. Therefore, propofol anesthesia may provide a useful hepatic protection during liver surgery.

Propofol improves recovery of the isolated working hypertrophic heart from ischaemia-reperfusion

The general anaesthetic propofol shows promise in protecting normal hearts against various cardiac insults, but little is known about its cardioprotective potential in hypertrophic hearts. This study tested the hypothesis that propofol at a clinically relevant dose would enhance functional recovery in hypertrophic hearts following ischaemia. Hypertrophic hearts from spontaneously hypertensive rats and hearts from their normotensive controls, Wistar Kyoto Rats, were equilibrated in the working mode prior to global normothermic ischaemia. Reperfusion commenced with 10 min in Langendorff mode, followed by 30-min working reperfusion. Functional performance was measured throughout the working mode, whilst reperfusion damage was assessed from myocardial troponin I release during Langendorff reperfusion. Where used, 4 μg/ml propofol was added 10 min before ischaemia and was washed out 10 min into working reperfusion. An additional protocol investigated recovery of hearts protected by normothermic hyperkalaemic cardioplegic arrest. Following 20-min ischaemia, reperfusion damage was significantly worse in hypertrophic hearts compared to normal hearts, whilst addition of propofol to hypertrophic hearts significantly improved the aortic flow (31 ± 5.8 vs. 11.6 ± 2.0 ml/min, n = 6-7 ± SE, p < 0.05). Propofol also conferred significant protection following 30-min ischaemia where the recovery of cardiac output and stroke volume was similar to that for cardioplegia alone. Incubation with propofol improved the NADH/NAD(+) ratio in freshly isolated cardiomyocytes from hypertrophic hearts, suggesting possible improvements in metabolic flux. These findings suggest that propofol at the clinically relevant dose of 4 μg/ml is as effective as cardioplegic arrest in protecting hypertrophic hearts against ischaemia-reperfusion.

In vivo and ex vivo effects of propofol on myocardial performance in rats with obstructive jaundice

BACKGROUND

Responsiveness of the "jaundiced heart" to propofol is not completely understood. The purpose of this study was to evaluate the effect of propofol on myocardial performance in rats with obstructive jaundice.

METHODS

Male Sprague-Dawley rats (n = 40) were randomly allocated into two groups, twenty underwent bile duct ligation (BDL), and 20 underwent a sham operation. Seven days after the surgery, propofol was administered in vivo and ex vivo (Langendorff preparations). Heart rate, left ventricular end-systolic pressure (LVESP) left ventricular end-diastolic pressure (LVEDP), and maximal rate for left ventricular pressure rise and decline (± dP/dtmax ) were measured to determine the influence of propofol on the cardiac function of rats.

RESULTS

Impaired basal cardiac function was observed in the isolated BDL hearts, whereas in vivo indices of basal cardiac function (LVESP and ± dP/dt) in vivo were significantly higher in rats that underwent BDL compared with controls. With low or intermediate concentrations of propofol, these indices of cardiac function were within the normal physiologic range in both groups, and responsiveness to propofol was unaffected by BDL. When the highest concentration of propofol was administrated, a significant decline in cardiac function was observed in the BDL group.

CONCLUSIONS

In rats that underwent BDL, basal cardiac performance was better in vivo and worse ex vivo compared with controls. Low and intermediate concentrations of propofol did not appear to impair cardiac function in rats with obstructive jaundice.

Propofol attenuation of hydrogen peroxide-mediated oxidative stress and apoptosis in cultured cardiomyocytes involves haeme oxygenase-1

BACKGROUND AND OBJECTIVE

Our aim was to investigate the cytoprotective effect of propofol against hydrogen peroxide (H2O2)-mediated injury and the effects on the haeme oxygenase-1 system, which is a possible new cytoprotective pathway of propofol.

METHODS

Primary cultured newborn rat cardiomyocytes were divided into five groups: (1) untreated (Group control); (2) treated with 200 micromol L(-1) H2O2 (Group H) and treated with 200 micromol L(-1) H2O2 in the presence of propofol (25, 50 and 100 micromol L(-1), (3) Group 25P + H, (4) Group 50P + H and (5) Group 100P + H, respectively); added with zinc protoporphyrin IX (ZnPPIX) (10 micromol L(-1)), a potent inhibitor of haeme oxygenase activity, or SC-3060 (0.2 micromol L(-1)), a specific synthetic inhibitor of nuclear factor kappaB. All were incubated for 6 h. The protective effects of propofol were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide cytotoxicity assay, the concentration of malondialdehyde, superoxide dismutase activity and cell apoptosis by enzyme-linked immunosorbent assay (ELISA). Reverse transcription polymerase chain reaction (RT-PCR) and western blot analysis were used to detect haeme oxygenase-1 expression.

RESULTS

Compared with H2O2, propofol concentrations (ranging from 50 to 100 micromol L(-1)) significantly increased haeme oxygenase-1 expression and decreased cardiomyocytes apoptosis, accompanied with a decrease in malondialdehyde, but with an increase in superoxide dismutase activity and cell activity (P < 0.05 and P < 0.01, respectively). The protective effects of propofol were mitigated by the addition of ZnPPIX. The addition of SC-3060 reversed propofol-induced haeme oxygenase-1 expression.

CONCLUSION

Propofol can protect cardiomyocytes against H2O2-mediated cytotoxicity in a dose-dependent manner and increase haeme oxygenase-1 expression, which may partly mediate the cytoprotective effects of propofol.

Inflammatory response and cardioprotection during open-heart surgery: the importance of anaesthetics

Open-heart surgery triggers an inflammatory response that is largely the result of surgical trauma, cardiopulmonary bypass, and organ reperfusion injury (e.g. heart). The heart sustains injury triggered by ischaemia and reperfusion and also as a result of the effects of systemic inflammatory mediators. In addition, the heart itself is a source of inflammatory mediators and reactive oxygen species that are likely to contribute to the impairment of cardiac pump function. Formulating strategies to protect the heart during open heart surgery by attenuating reperfusion injury and systemic inflammatory response is essential to reduce morbidity. Although many anaesthetic drugs have cardioprotective actions, the diversity of the proposed mechanisms for protection (e.g. attenuating Ca(2+) overload, anti-inflammatory and antioxidant effects, pre- and post-conditioning-like protection) may have contributed to the slow adoption of anaesthetics as cardioprotective agents during open heart surgery. Clinical trials have suggested at least some cardioprotective effects of volatile anaesthetics. Whether these benefits are relevant in terms of morbidity and mortality is unclear and needs further investigation. This review describes the main mediators of myocardial injury during open heart surgery, explores available evidence of anaesthetics induced cardioprotection and addresses the efforts made to translate bench work into clinical practice.

Mitochondrial permeability transition pore opening as an endpoint to initiate cell death and as a putative target for cardioprotection

In recent years, mitochondria have been recognized as regulators of cell death via both apoptosis and necrosis in addition to their essential role for cell survival. Cellular dysfunctions induced by intra- or extracellular insults converge on mitochondria and induce a sudden increase in permeability of the inner mitochondrial membrane, the so-called mitochondrial permeability transition. The mitochondrial permeability transition is caused by the opening of permeability transition pores (PTP) in the inner mitochondrial membrane with subsequent loss of ionic homeostasis, matrix swelling and outer membrane rupture. The detailed molecular mechanisms underlying the PTP-induced cellular dysfunction during cardiac pathology such as ischemia/reperfusion or post-infarction remodeling remain to be elucidated. However, a growing body of evidence supports the concept that pharmacological inhibition of the PTP is an effective and promising strategy for the protection of the heart against ischemia/reperfusion injury and for attenuation of the remodeling process which contributes to heart failure. This review summarizes and discusses current data on i) the structure and function of the PTP, ii) possible mechanisms and consequences of PTP opening and iii) the inhibition of PTP opening as a therapeutic approach for treatment of heart disease.

Effects of propofol on intracellular Ca2+ homeostasis in human astrocytoma cells

The effects of propofol, a short-acting general anesthetic, upon cell growth and Ca(2+) signaling in a human astrocytic cell line were examined. Exposure of cells to graded concentrations of propofol resulted in a dose-dependent decrease in cell number with an inhibitory concentration of cell viability (IC50) of 31.7+/-1.2 microM. To evaluate the changes in intracellular Ca(2+) homeostasis induced by propofol, cytoplasmic and mitochondrial Ca(2+) were measured by fluorescence imaging. Mitochondrial Ca(2+) increased while cytoplasmic Ca(2+) decreased significantly at a propofol concentration lower than the IC50 (10 microM for 24 h, 1 microM for 72 h). In addition, propofol diminished the Ca(2+) response induced by fetal bovine serum (FBS). To determine the source of Ca(2+) alterations induced by propofol, pharmacologic agents targeting intracellular Ca(2+) homeostasis mechanisms were used. Nifedipine, an L-type Ca(2+) channel blocker, decreased FBS-induced Ca(2+) response of control cells to a level similar to propofol treated cells. However, diazoxide (a K(+)-ATP channel opener) administered 1 h before FBS addition restored the FBS response in propofol treated cells to a level similar to control. In addition, diazoxide increased mitochondrial Ca(2+) in control cells to a level comparable to propofol treated cells suggesting activation of these channels by propofol treatment. Addition of 1 muM RU-360 (a selective blocker of the mitochondrial Ca(2+) uniporter) for 30 min prior to propofol treatment restored mitochondrial and cytoplasmic Ca(2+) to control levels. These data suggest that voltage operated Ca(2+) channels, mitochondrial Ca(2+) and K(+)-ATP channels may be targets of propofol action in astrocytes.

Propofol for sedation in neuro-intensive care

Interventions in the intensive care unit often require that the patient be sedated. Propofol is a widely used, potent sedative agent that is popular in critical care and operating room settings. In addition to its sedative qualities, propofol has neurovascular, neuroprotective, and electroencephalographical effects that are salutory in the patient in neurocritical care. However, the 15-year experience with this agent has not been entirely unbesmirched by controversy: propofol also has important adverse effects that must be carefully considered. This article discusses and reviews the pharmacology of propofol, with specific emphasis on its use as a sedative in the neuro-intensive care unit. A detailed explanation of central nervous system and cardiovascular mechanisms is presented. Additionally, the article reviews the literature specifically pertaining to neurocritical care use of propofol.

Autonomic Mechanisms in the Age-Related Hypotensive Effect of Propofol

We hypothesized that age-related differences in cardiovascular regulatory processes play a role in the augmented vasodepressor response to anesthetic induction with propofol in older subjects. To test this hypothesis, differences in baroreceptor responsiveness (BR) were first demonstrated in young adult (6-12 mo, n=12) and aged (>42 mo, n=12) New Zealand rabbits, and then the vasodepressor effect of propofol was compared in both the absence and presence of ganglionic blockade. For each age group, half of the animals were pretreated with 20 mg/kg IV hexamethonium (HEX) with the remaining half designated as controls. BR was first assessed by plotting cardiac cycle length as a function of the decline in mean arterial blood pressure (MAP) produced by multiple IV boluses of tri-nitroglycerine. Propofol was then given as an IV bolus of 4.5, 6.4, or 8.4 mg/kg over 3 s. Each animal was studied three times, receiving a single dose in variable order with at least 7 days between injections. In control animals, marked age-related differences in BR were evident and propofol produced larger peak decreases in MAP in older rabbits at all doses. HEX pretreatment abolished BR for both young and aged rabbits. However, after HEX administration the vasodepressor response to propofol in young animals was enhanced by 150% at 4.5, 125% at 6.4, and 61% at 8.4 mg/kg, respectively, whereas the impact in aged animals was only 25%, 30%, and -10%, respectively. These data support the hypothesis that age-related enhancement of propofol-induced hypotension is largely a reflection of diminished BR.

Strategies to Optimise Propofol-Opioid Anaesthesia

Propofol-opioid combinations are widely used in today's anaesthetic practice. Over the past 20-30 years the pharmacology of these agents has been described in increasingly greater detail. Together with novel intravenous administration devices and improved anaesthetic depth monitoring, this has created a basis for the optimisation of the administration of propofol-opioid anaesthesia. This article describes the current strategies regarding the application of this type of anaesthesia, focusing on three strategic tools: (i) application of pharmacokinetic-pharmacodynamic knowledge of propofol and the opioids, with particular attention to pharmacodynamic interactions between them; (ii) the use of state-of-the-art administration techniques; and (iii) the application of bispectral index monitoring. Together, these techniques have improved the level of control, the flexibility and the safety of anaesthetic practice.

Propofol displays no protective effect against hypoxia/reoxygenation injury in rat liver slices

Using precision-cut liver slices (20-25 mg wet weight) from male Wistar rats, we examined whether clinically relevant propofol concentrations have hepatoprotective or -toxic effects during hypoxia/reoxygenation. Slices were preincubated for 2 h in sealed roller vials (three slices per vial) containing Waymouth's medium (37 degrees C; 95% oxygen/5% CO(2)). Then, propofol or Intralipid was added to create four different groups (control, Intralipid, small-concentration propofol [0.5-1.5 micro g/mL], and large-concentration propofol [2.0-6.0 micro g/mL]). Thereafter, each group was incubated for 4 h under 95% oxygen/5% CO(2) (no hypoxia) or for 2 h under 100% nitrogen plus 2 h under 95% oxygen/5% CO(2) (hypoxia/reoxygenation). Slice viability and hypoxia/reoxygenation injury were assessed at 2, 3, and 4 h after incubation began by using the slice intracellular K(+) concentration, energy status (adenosine triphosphate content, total adenine nucleotides content, and energy charge), and liver enzyme leakage (aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase). Propofol and Intralipid caused a significant delay in energy charge recovery in comparison with the control. There were no significant differences between the propofol groups and the other two groups in intracellular K(+) content or liver enzyme leakage. Propofol had no hepatotoxic effect under no-hypoxia conditions in rat liver slices, nor did it have a protective effect against hypoxia/reoxygenation-induced hepatic injury.

IMPLICATIONS

Propofol had no hepatotoxic effect under no-hypoxia conditions in rat liver slices, nor did it have a protective effect against hypoxia/reoxygenation-induced hepatic injury.

Effects of propofol on ischemia and reperfusion in the isolated rat heart compared with thiamylal

The aim of the present study was to investigate whether clinical doses of propofol and thiamylal affect oxygen free radical production and intracellular calcium concentration ([Ca2+]i) in the post-ischemic reperfused heart. Forty-eight rat hearts were perfused with a Langendorff system and loaded with Fura-2 / AM as a [Ca2+]i marker. The hearts were divided into 6 groups as follows (each group: n = 8); Group S (saline), Group TL (thiamylal 100 microM), Group TH (thiamylal 300 microM), Group I (Intralipid), Group PL (propofol 3 microM), and Group PH (propofol 10 microM). All hearts were initially perfused for 5 min as control aerobic perfusion. Afterwards, no-flow ischemia was induced for 15 min, followed by reperfusion for 20 min. The formation of hydroxyl radicals in the coronary effluent was measured with high performance liquid chromatography using salicylic acid. At the beginning of the ischemia and reperfusion periods, increases in systolic and diastolic [Ca2+]i were observed in all groups except Group TH. The high dose of thiamylal significantly suppressed this initial increase in cytosolic [Ca2+]i (Group S 1.30+/-0.15; Group TL 0.99+/-0.17; Group TH 0.70+/-0.09, at 1 min after reperfusion; systolic [Ca2+]i : p < 0.05). Total DHBAs in the coronary effluent of all groups increased significantly 1 min after reperfusion, however, there were no significant differences among the groups. Clinical doses of propofol had no significant effect on myocardial function and [Ca2+]i before and after ischemia, whereas thiamylal suppressed the increase in [Ca2+]i during ischemia and reperfusion. However, free radical formation during reperfusion was unaffected by thiamylal and propofol.

The differential effect of propofol on contractility of isolated myocardial trabeculae of rat and guinea-pig

1. The effects of propofol on myocardial contractility were studied in rat, in which the contractile activation mainly depends on calcium derived from the sarcoplasmic reticulum (SR), and guinea-pig, in which transsarcolemmal influx of calcium plays a major role. 2. Intact and chemically skinned trabeculae from the right ventricle were studied. Intact trabeculae were electrically stimulated and force development during steady state and post rest contractions was measured. In saponin skinned trabeculae Ca(2+) uptake and release by the SR was studied. In Triton skinned trabeculae the influence of propofol on calcium sensitivity of the myofilaments was studied. 3. In intact rat trabeculae propofol in concentrations of 28, 112 and 280 microM did not change peak force development nor the pattern of post rest contraction. In guinea-pig trabeculae propofol significantly reduced peak force to respectively 64, 40 and 23% of control values and the post rest contractions were potentiated. In skinned trabeculae propofol did not affect Ca(2+) handling by the SR, nor did it change force production and Ca(2+) sensitivity of the myofilaments. 4. This study shows that, in contrast to rat, in guinea-pig propofol directly depresses myocardial contractility, probably by decreasing transsarcolemmal Ca(2+) influx. There is no significant influence of propofol on Ca(2+) handling by the SR, nor on the contractile proteins.

Propofol anesthesia for outpatient oral and maxillofacial surgery

Propofol is a sedative-hypnotic intravenous anesthetic agent that has gained wide use in outpatient oral and maxillofacial surgery since its clinical introduction in 1985. Propofol has several therapeutic advantages that make it an excellent choice for use in all phases of general anesthesia and conscious sedation. It is associated with minimal side effects, a controllable anesthetic state, and rapid recovery. This review of propofol discusses its pharmacologic character, administration, and side effects and presents anesthetic drug interaction information and comparisons.

Elucidating the molecular mechanism of the permeability transition pore and its role in reperfusion injury of the heart

First, we present a summary of the evidence for our model of the molecular mechanism of the permeability transition (MPT). Our proposal is that the MPT occurs as a result of the binding of mitochondrial cyclophilin (CyP-D) to the adenine nucleotide translocase (ANT) in the inner mitochondrial membrane. This binding is enhanced by thiol modification of the ANT caused by oxidative stress or other thiol reagents. CyP-D binding enhances the ability of the ANT to undergo a conformational change triggered by Ca2+. Binding of ADP or ATP to a matrix site of the ANT antagonises this effect of Ca2+; modification of other ANT thiol groups inhibits ADP binding and sensitises the MPT to [Ca2+]. Increased membrane potential changes the ANT conformation to enhance ATP binding and hence inhibit the MPT. Our most recent data shows that a fusion protein of CyP-D and glutathione-S-transferase immobilised to Sepharose specifically binds the ANT from Triton-solubilised inner mitochondrial membranes in a cyclosporin A (CsA) sensitive manner. Second we summarise the evidence for the MPT being a major factor in the transition from reversible to irreversible injury during reperfusion of a heart following a period of ischaemia. We describe how in the perfused heart [3H]deoxyglucose entrapment within mitochondria can be used to measure the opening of MPT pore in situ. During ischaemia pore opening does not occur, but significant opening does occur during reperfusion, and recovery of the heart is dependent on subsequent pore closure. Pore opening is inhibited by the presence in the perfusion medium of pyruvate and the anaesthetic propofol which both protect the heart from reperfusion injury. Third we discuss how the MPT may be involved in determining whether cell death occurs by necrosis (extensive pore opening and ATP depletion) or apoptosis (transient pore opening with maintenance of ATP).