Effects Of Propofol Anesthesia Research Articles

The effects of propofol anaesthesia on molecular-enriched networks during resting-state and naturalistic listening

Placing a patient in a state of anaesthesia is crucial for modern surgical practice. However, the mechanisms by which anaesthetic drugs, such as propofol, impart their effects on consciousness remain poorly understood. Propofol potentiates GABAergic transmission, which purportedly has direct actions on cortex as well as indirect actions via ascending neuromodulatory systems. Functional imaging studies to date have been limited in their ability to unravel how these effects on neurotransmission impact the system-level dynamics of the brain. Here, we leveraged advances in multi-modal imaging, Receptor-Enriched Analysis of functional Connectivity by Targets (REACT), to investigate how different levels of propofol-induced sedation alter neurotransmission-related functional connectivity (FC), both at rest and when individuals are exposed to naturalistic auditory stimulation. Propofol increased GABA-A- and noradrenaline transporter-enriched FC within occipital and somatosensory regions respectively. Additionally, during auditory stimulation, the network related to the dopamine transporter showed reduced FC within bilateral regions of temporal and mid/posterior cingulate cortices, with the right temporal cluster showing an interaction between auditory stimulation and level of consciousness. In bringing together these micro- and macro-scale systems, we provide support for both direct GABAergic and indirect noradrenergic and dopaminergic-related network changes under propofol sedation. Further, we delineate a cognition-related reconfiguration of the dopaminergic network, highlighting the utility of REACT to explore the molecular substrates of consciousness and cognition.

EEG and ECG Power Spectrum Analysis of Sedative Effects on Propofol-Anesthetized Rats with Electroacupuncture.

Background In previous studies, electroacupuncture (EA) with 2/15 Hz has been shown to enhance the sedative effects in general anesthesia patients. Central lateral thalamic stimulation of 50 Hz showed an arousal effect in macaques. Therefore, it is worth studying the sedative effect of EA at peripheral acupoints with different frequencies, especially the frequency of around 50 Hz. Methods Rats were anesthetized under the constant infusion of propofol and EA at Zusanli (ST36) and Neiguan (PC6) locations. Electroencephalography (EEG) and heart rate were continuously recorded before and after the intervention by EA in the C group (control), LEA group (low-frequency group, 2/15 Hz diffuse/dense wave EA stimulation), and HEA group (high-frequency group, 50 Hz stimulation). Results In the LEA group, a significant increase in the power of the delta component with a decrease in the alpha component (p < 0.05) was observed after EA stimulation. In the HEA group, significant increases in the powers of alpha and beta components of EEG (p < 0.05) and a decrease in the delta component of EEG were observed (p < 0.05). The phenomenon is also shown in full-frequency waves. In addition, a significant decrease in the low-frequency/high-frequency ratio parameter was observed in the LEA group. Conclusions EA at bilateral ST36 and PC6 can enhance the sedative effects of propofol anesthesia in low-frequency stimulation but lighten the sedative effects in high-frequency (50 Hz) stimulation. The sympathetic-vagal balance was affected due to low-frequency EA.

Effects of Propofol Anesthesia on Pyroptosis and the Nod-Like Receptor Protein 3/Caspase-1 Pathway in the Neonatal Rat Hippocampus

To investigate the effect and related mechanism of propofol anesthesia on pyroptosis in neonatal rat hippocampus. Neonatal rats were divided into a control group (injected intraperitoneally with saline), a propofol group (injected intraperitoneally with 80 mg/kg propofol) and a propofol+MCC950 group (injected intraperitoneally with 80 mg/kg propofol and 10 mg/kg MCC950) and administered for 5 d. The day after the end of drug administration, hippocampi were analyzed for pyroptosis by transferase dUTP nick end labeling assay and for interleukin beta-1, interleukin-18 levels, nod-like receptor protein 3, ASC and caspase-1 protein expression in the hippocampus were determined by Western blotting; at the end of drug administration on the 19th d, the escape latency, the number of crossing the platform and the percentage of time spent in the target quadrant were recorded in the water maze test. Pyroptosis, levels of interleukin-beta and interleukin-18 and the protein levels of nod-like receptor protein 3, ASC and caspase-1, as well as the escape latency of the rats of hippocampal tissues were significantly higher in the propofol group than those in the control group (p<0.05) and the percentage of time crossing the platform and staying in the target quadrant was significantly lower (p<0.05) in the propofol group than those in the control group; pyroptosis, levels of interleukin-beta and interleukin-18 and the protein levels of nod-like receptor protein 3, ASC and caspase-1, as well as the escape latency of the rats of propofol+MCC950 group were significantly lower in the propofol group than those in the control group (p<0.05), whereas the number of crossing the platform and the percentage of time spent in the target quadrant were significantly higher (p<0.05). Propofol anesthesia may trigger inflammatory responses by activating the nod-like receptor protein 3/caspase-1 pathway, which in turn induces pyroptosis in the neonatal rat hippocampus, leading to reduced learning and memory performance.

The Effect of Propofol Anesthesia on the Pain Severity and Frequency of Migraine Attacks in Patients with Chronic Migraine Headache over a Six Month Follow Up: An Observational Study.

Propofol is a short-acting intravenous anesthetic that is commonly used for induction and maintenance of anesthesia. Subanesthetic low doses of propofol has also been used to treat intractable migraine attacks in emergency wards with dramatic results. However, there is little information on the long-term efficacy of this drug in migraine headaches. The aim of this nonrandomized prospective observational study was to assess the effect of propofol anesthesia on the pain severity and frequency of migraine attacks in a 6-month follow-up period after anesthesia in patients with migraine headaches. The study was conducted on 51 known cases of migraine ranging in age from 21 to 66 years. Before anesthesia, patients completed a questionnaire including their characteristics, pain intensity of the headache using a visual analog scale, and a number of headache repetitions per month. All patients received propofol as the main anesthetic agent. At the end of anesthesia, the total amount of propofol usage was recorded. Patients were then followed up by telephone in the first, third, and sixth months after anesthesia, and the severity and frequency of the headache were recorded. Pain intensity or pain frequency significantly improved in 22 patients (43.1%), remained unchanged in 24 (47%), and worsened in 5 cases (9.8%) 6 months after anesthesia compared to before the anesthesia. In conclusion, since about half of the patients had significant improvement in the headache, propofol anesthesia may be considered as an acceptable anesthetic method in patients with migraine.

The Effects of Propofol Anesthesia on Lipid Profile and Some Biochemical Indices in Cats

The aim of the present study was to evaluate lipid profile (triglyceride, total cholesterol, HDL, LDL, and VLDL), pancreas (lipase and amylase), liver (AST, ALT, and ALP), blood urea nitrogen, creatinine, uric acid, sodium and potassium function indicators in cats undergoing two different durations of anesthesia with propofol. Ten adult female cats were randomly divided into two groups (n= 5) and anaesthetized with propofol 1% (induction: 8 mg/kg; infusion: 0.3 mg/kg/min) for either 45 or 90 minutes. Blood samples were collected at predetermined intervals up to 72 hours later. Comparison of the measured variables between treatments did not show significant differences. Triglyceride and cholesterol levels showed significant increase after induction of anesthesia (P < .05). The highest triglyceride and cholesterol values were recorded at 6 and 24 hours. HDL was lower while LDL and VLDL were higher at several time points after anesthesia (P < .05). Higher values of lipase, ALT and AST were detected after induction (P < .05). All the observed alterations were within normal ranges. In conclusion, propofol anesthesia was associated with some changes in lipid profile, as well as pancreatic and liver function indices, which should be considered in clinical situations. It seems that in the absence of pre- or co-existing disturbances, induction and maintenance of anesthesia with propofol did not carry additional risk to cats.

Applications of Force During Colonoscopy and the Effect of Propofol Anesthesia

Applications of Force During Colonoscopy and the Effect of Propofol Anesthesia

Effects of Propofol Anaesthesia Pre-Medicated with Xylazine on Serum Biochemical Profiles and Sleep Pattern in Red Sokoto Goats

This study was conducted with the objective to compare the sleep pattern and biochemical changes during general anesthesia at different timing interval with the baseline information using Propofol as the agent of choice and xylazine as a pre-medicant at 4 mg kg-1 intravenously and 0.025 mg kg-1 intramuscularly respectively. The onset of anaesthesia was rapid (30.1±11.3 seconds), the anaesthetic induction, surgical plane and recovery were good. There was a significant difference (P&lt;0.05) between baseline and other timing intervals in the rectal temperature, respiratory rate, systolic and diastolic blood pressure, but there was no significant difference (P&gt;0.05) in pulse rate. Similarly, a statistically significant difference (P&lt;0.05) was observed in the serum calcium ion, magnesium ion, hydrogen bicarbonate ion, Alkaline Phosphatase (ALP), creatinine, total protein and glucose levels, but there was no significant difference (P&gt;0.05) in the sodium ion, potassium ion, Alanine aminotransferase (ALT), Albumin (ALB), Aspartate aminotransferase (AST), , and Urea. It was concluded that the combination of Propofol and Xylazine at 4mgkg-1 and 0.25mgkg-1 respectively can be effectively and safely used for induction and maintenance of anaesthesia in Red Sokoto goats. It was also noted that recovery was smooth without any violence. The combination was also observed to have minimal effects on the clinico-biochemical parameters of Red Sokoto goats.

Effects of propofol anesthesia on the processing of noxious stimuli in the spinal cord and the brain

Drug-induced unconsciousness is an essential component of general anesthesia, commonly attributed to attenuation of higher-order processing of external stimuli and a resulting loss of information integration capabilities of the brain. In this study, we investigated how the hypnotic drug propofol at doses comparable to those in clinical practice influences the processing of somatosensory stimuli in the spinal cord and in primary and higher-order cortices. Using nociceptive reflexes, somatosensory evoked potentials and functional magnet resonance imaging (fMRI), we found that propofol abolishes the processing of innocuous and moderate noxious stimuli at low to medium concentration levels, but that intense noxious stimuli evoked spinal and cerebral responses even during deep propofol anesthesia that caused profound electroencephalogram (EEG) burst suppression. While nociceptive reflexes and somatosensory potentials were affected only in a minor way by further increasing doses of propofol after the loss of consciousness, fMRI showed that increasing propofol concentration abolished processing of intense noxious stimuli in the insula and secondary somatosensory cortex and vastly increased processing in the frontal cortex. As the fMRI functional connectivity showed congruent changes with increasing doses of propofol – namely the temporal brain areas decreasing their connectivity with the bilateral pre-/postcentral gyri and the supplementary motor area, while connectivity of the latter with frontal areas is increased – we conclude that the changes in processing of noxious stimuli during propofol anesthesia might be related to changes in functional connectivity.

Comparison of Propofol with Desflurane for Laparoscopic Sleeve Gastrectomy in Morbidly Obese patients: A Prospective Randomized Trial

Background: Laparoscopic sleeve gastrectomy has become one of the most effective treatment options for adults with severe obesity. However, optimal anesthetic management for laparoscopic sleeve gastrectomy has not been described yet. Methods: In this prospective randomized study, we compared the effects of propofol anesthesia (Group 1) with desflurane anesthesia (Group II) in morbid obese patients for laparoscopic sleeve gastrectomy. We compared postoperative recovery and hemodynamic parameters of the patients. We also investigated the changes in tracheal cuff pressure and peak airway pressure of these obese patients during orogastric tube insertion and peritoneal CO2 insufflation. Results: Eye opening and extubation time were longer in the propofol group than in the desflurane group (p 0.05). Six patients in Group I and eight patients in Group II had sore throat (p > 0.05). Eight patients in Group I a...

Electrocorticographic delineation of human auditory cortical fields based on effects of propofol anesthesia

The functional organization of human auditory cortex remains incompletely characterized. While the posteromedial two thirds of Heschl's gyrus (HG) is generally considered to be part of core auditory cortex, additional subdivisions of HG remain speculative. To further delineate the hierarchical organization of human auditory cortex, we investigated regional heterogeneity in the modulation of auditory cortical responses under varying depths of anesthesia induced by propofol. Non-invasive studies have shown that propofol differentially affects auditory cortical activity, with a greater impact on non-core areas. Subjects were neurosurgical patients undergoing removal of intracranial electrodes placed to identify epileptic foci. Stimuli were 50Hz click trains, presented continuously during an awake baseline period, and subsequently, while propofol infusion was incrementally titrated to induce general anesthesia. Electrocorticographic recordings were made with depth electrodes implanted in HG and subdural grid electrodes implanted over superior temporal gyrus (STG). Depth of anesthesia was monitored using spectral entropy. Averaged evoked potentials (AEPs), frequency-following responses (FFRs) and high gamma (70–150Hz) event-related band power were used to characterize auditory cortical activity. Based on the changes in AEPs and FFRs during the induction of anesthesia, posteromedial HG could be divided into two subdivisions. In the most posteromedial aspect of the gyrus, the earliest AEP deflections were preserved and FFRs increased during induction. In contrast, the remainder of the posteromedial HG exhibited attenuation of both the AEP and the FFR. The anterolateral HG exhibited weaker activation characterized by broad, low-voltage AEPs and the absence of FFRs. Lateral STG exhibited limited activation by click trains, and FFRs there diminished during induction. Sustained high gamma activity was attenuated in the most posteromedial portion of HG, and was absent in all other regions. These differential patterns of auditory cortical activity during the induction of anesthesia may serve as useful physiological markers for field delineation. In this study, the posteromedial HG could be parcellated into at least two subdivisions. Preservation of the earliest AEP deflections and FFRs in the posteromedial HG likely reflects the persistence of feedforward synaptic activity generated by inputs from subcortical auditory pathways, including the medial geniculate nucleus.

Effect of propofol anesthesia on resting state brain functional connectivity in Indian population with chronic back pain.

Functional magnetic resonance imaging (fMRI) studies in healthy volunteers have shown alterations in brain connectivity following anesthesia as compared to the awake state. It is not known if the anesthesia-induced changes in brain connectivity are different in a pathological state. This study aims to evaluate changes in the resting state functional connectivity in the brain, after propofol anesthesia, in patients with chronic back pain (CBP). Fourteen adults with CBP were included in this prospective study over 6 months. After excluding structural brain pathology, a resting state fMRI was performed in the awake state, and the sequences were repeated after propofol anesthesia. The primary outcome measure was change in resting state connectivity after propofol. Student's t-test was performed between the pre and post-propofol sedation data of all patients with total brain volume as covariates of interest. A repeated measures analysis of variance was used to compare pre- and post-propofol changes in cardiorespiratory parameters. There were 8 male and 6 female patients in the study, and the mean age of the study population was 46.9 ± 11.3 years. Propofol sedation resulted in an increased strength of functional connectivity between the posterior cingulate cortex (PCC) and thalamus in patients with CBP, whereas there was a generalized decrease in functional integration within the large scale brain networks. The changes in cardiorespiratory parameters before and after propofol administration were not statistically significant. Strengthening of functional connectivity was seen between PCC and thalamus with decrease in large scale brain networks following propofol anesthesia in patients with CBP. These changes are similar to those previously described in normal volunteers.

Effect of propofol anesthesia on skin flap survival in rat; comparison with ketamine

Effect of propofol anesthesia on skin flap survival in rat; comparison with ketamine

Comparison of the Effects of Propofol Anaesthesia and Desflurane Anaesthesia on Neutrophil/Lymphocyte Ratios After Coronary Artery Bypass Surgery

Objective: Coronary artery bypass surgery with cardiopulmonary bypass can induce postoperative systemic leukocytic alterations including leukocytosis, neutrophilia, or lymphopenia. The present study aims to compare the effects of propofol and desflurane anaesthesia on the leukocytic alterations including neutrophil-to-lymphocyte ratios after coronary artery bypass surgery. Materials and Methods: Sixty patients scheduled for coronary artery bypass surgery were randomly assigned into two groups: group P (n=30), which were anaesthesised with propofol (intravenous anaesthesia) and group D, which were anaesthesised with desflurane (inhalational anesthesia). Differential counts of leukocytes with neutrophil/lymphocyte ratios of peripheral blood were obtained just before anaesthesia induction (for basal values), at the postoperative 12th, 24th, and 48th hours. Results: At the postoperative 12th decrease in lymphocyte counts in group P was significantly lower than in group D (1.23 ± 0.81, 0.92 ± 1.01, respectively, with a p value of <0.001). Depending on this difference, neutrophil/lymphocyte ratios in group P were lower than in group D, which was statistically significant (11.21 ± 5.01, 22.81 ± 15.24, respectively, with a p value of <0.001). At postoperative 48th hour, it was seen that the statistically significant difference between groups on the basis of lymphocyte counts and neutrophil/lymphocyte ratios dissapeared. But a statistically significant difference appeared between the two groups on the basis of neutrophil counts (in group P 6.57 ± 2.05, in group D 10.20 ± 5.26; p<0.001) Conclusion: Comparing with desflurane anaesthesia, propofol anaesthesia favorably but transiently modifies leukocytic alterations, including neutrophil-to-lymphocyte ratios in peripheral blood during postoperative period of coronary artery bypass surgery. Key Words: Coronary Artery Surgery; Propofol And Desflurane Anesthesia; Neutrophil/Lymphocyte Ratio.

Effects of ketamine and propofol on motor evoked potentials elicited by intracranial microstimulation during deep brain stimulation.

Few preclinical or clinical studies have evaluated the effect of anesthetics on motor evoked potentials (MEPs), either alone or in the presence of conditioning stimuli such as deep brain stimulation (DBS). In this study we evaluated the effects of two commonly used anesthetic agents, propofol and ketamine (KET), on MEPs elicited by intra-cortical microstimulation of the motor cortex in a rodent model with and without DBS of the dentatothalamocortical (DTC) pathway. The effects of propofol anesthesia on MEP amplitudes during DTC DBS were found to be highly dose dependent. Standard, but not high, dose propofol potentiated the facilitatory effects of 30 Hz DTC DBS on MEPs. This facilitation was sustained and phase-dependent indicating that, compared to high dose propofol, standard dose propofol has a beta-band excitatory effect on cortical networks. In contrast, KET anesthetic demonstrated a monotonic relationship with increasing frequencies of stimulation, such that the highest frequency of stimulation resulted in the greatest MEP amplitude. KET also showed phase dependency but less pronounced than standard dose propofol. The results underscore the importance of better understanding the complex effects of anesthetics on cortical networks and exogenous stimuli. Choice of anesthetic agents and dosing may significantly confound or even skew research outcomes, including experimentation in novel DBS indications and paradigms.

Effect of propofol anesthesia on force application during colonoscopy

Sedation is frequently used during colonoscopy to control patient discomfort and pain. Propofol is associated with a deeper level of sedation than is a combination of a narcotic and sedative hypnotic and, therefore, may be associated with an increase in force applied to the colonoscope to advance and withdraw the instrument. To compare force application to the colonoscope insertion tube during propofol anesthesia and moderate sedation. An observational cohort study of 13 expert and 12 trainee endoscopists performing colonoscopy in 114 patients. Forces were measured by using the colonoscopy force monitor, which is a wireless, handheld device that attaches to the insertion tube of the colonoscope. Community ambulatory surgery center and academic gastroenterology training programs. Patients undergoing routine screening or diagnostic colonoscopy with complete segment force recordings. Axial and radial forces and examination time. Axial and radial forces increase and examination time decreases significantly when propofol is used as the method of anesthesia. Small study, observational design, nonrandomized distribution of sedation type and experience level, different instrument type and effect of prototype device on insertion tube manipulation. Propofol sedation is associated with a decrease in examination time and an increase in axial and radial forces used to advance the colonoscope.

Effects of propofol anesthesia on hippocampal PKA-CREB signaling pathway in neonatal rats

Objective To evaluate the effects of propofol anesthesia on hippocampal protein kinase A (PKA)-cAMP response element binding protein (CREB) signaling pathway in neonatal rats.Methods One hundred and seventy-five male Sprague-Dawley rats,aged 7 days,weighing 8-15 g,were randomly divided into 5 groups (n =35 each) using a random number table:control group (C group) and propofol 25,50,100 and 200 mg/kg groups (P~ groups).Groups P1 and P2 received intraperitoneal propofol 25 and 50 mg/kg,respectively.Groups P3 and P4 received intraperitoneal propofol 100 and 200 mg/kg,respectively,and after righting reflex completely recovered,an increment of propofol 50 mg/kg was given until the total amount was finished.Five animals in each group were chosen and arterial blood samples were obtained immediately after the animals were fully awake for blood gas analysis.Five animals in each group were chosen at 2 h after fully awake and the age of 9 weeks,the rats were sacrificed and their brains were removed for microscopic examination of the ultrastructure of hippocampal neurons and for determination of PKA mRNA,CREB mRNA,PKA protein and pCREB protein in hippocampus (using RT-PCR and Western blot analysis).Results There was no significant difference in the indexes of blood gas analysis anong the five groups (P ＞ 0.05).Nuclear swelling and fragmentation,chromatin condensation,apoptotic bodies,decreased number of synapses and widened synaptic space were observed in P2,P3 and P4 groups.Compared with group C,the expression of PKA mRNA,CREB mRNA,PKA protein and pCREB protein was significantly down-regulated at 2 h after fully awake and the age of 9 weeks in P1,P2,P3 and P4 groups (P ＜ 0.05).Conclusion The mechanism by which propofol anesthesia induces neurotoxicity in neonatal rats may be related to inhibition of the activity of PKA-CREB signaling pathway. Key words: Propofol; Infant, newborn; Cyclic AMP-dependent protein kinases; Cyclic AMP response element-binding protein; Hippocampus

Effect of propofol anesthesia on expression of β-secretase 1 and content of anyloid beta protein 1-42 in neonatal rat hippocampus

Objective To investigate the effect of propofol anesthesia on the expression of β-secretase 1 (BACE1) and content of anyloid beta protein 1-42 (Aβ1-42) in the neonatal rat hippocampus.Methods Ninety Sprague-Dawley rats,aged 7 days,weighing 12-16 g,were randomly divided into 3 groups ( n =30 each):control group (group C),single dose of propofol anesthesia group (group SP),and repeated doses of propofol anesthesia group (group RP).Group C received intraperitoneal normal saline 7.5 ml/kg once a day for 7 consecutive days.Group SP received normal saline 7.5 ml/kg once a day for 6 consecutive days and propofol 75 mg/kg on 7th day.Group RP received propofol 75 mg/kg once a day for 7 consecutive days.Six rats in each group were chosen at 15 min after the end of injection on 7th day and blood samples were taken from the left ventricle for determination of the blood glucose level and for blood gas analysis.Eight animals in each group were sacrificed on 1st,3rd and 7th day after the end of injection on 7th day to determine the expression of BACE1 (using Western blot) and content of Aβ1-42 in the hippocampus (by ELISA).Results Compared with groups C and SP,the expression of BACE1 was up-regulated and the content of Aβ1-42 was significantly increased at each time point in group RP ( P ＜ 0.01 ).There was no significant difference in the expression of BACE1 and content of Aβ1-42 at each time point between groups C and SP ( P ＞ 0.05).Conclusion Repeated doses of propofol up-regulate the expression of BACE1 and increase the content of Aβ1-42 in neonatal rat hippocampus,which may be one of the mechanisms by which propofol leads to long-term cognitive dysfunction.Single dose of propofol does not have the effect. Key words: Propofol; Hippocampus; Amyloid beta-protein; Infant, newborn; β-secretase 1

Effect of propofol anesthesia on electroconvulsive therapy-induced hyperphosphorylation of Tau protein in hippocampus in depressed rats

Objective To investigate the effect of propofol anesthesia on electroconvulsive therapy (ECT)-induced hyperphosphorylation of Tau protein in hippocampus in depressed rats.Methods Thirty-two female WYK rats in which the total score was 30-120 after Open-field test,aged 24 weeks,weighing 200-250 g,were randomly divided into 4 groups ( n =8 each):control group (group C),propofol group (group P),ECT group (group E)and propofol + ECT group (group PE).In groups C and E,the animals received intraperitoneal normal saline 5 ml,and in addition the animals received ECT 15 min later in group E.In groups P and PE,the animals received intraperitoneal 100 mg/kg propofol 5 ml,and in addition the animals received ECT 15 min later in group PE.The learning and memory function was assessed by Morris water maze test at 24 h after ECT.The animals were sacririced at 6 h after Morris water maze test and the hippocampal tissues were removed for determination of the expression of phosphorylated Tau protein.Results Compared with group C,the escape latency was significantly prolonged,the swimming time was significantly shortened in groups P,E and PE,the expression of phosphorylated Tau protein in hippocampus was down-regulated in group P,and the expression of phosphorylated Tau protein in hippocampus was up-regulated in group E ( P ＜ 0.05).Compared with group E,the escape latency was significantly shortened,the swimming time was significantly prolonged,and the expression of phosphorylated Tau protein in hippocampus was down-regulated in group PE (P ＜0.05).Conclusion The mechanism by which propofol anesthesia improves cognitive impairment induced by ECT may be related to inhibition of hyperphosphorylation of Tau protein in hippocampus in depressed rats. Key words: Propofol; Electroconvulsive therapy; Depression; tau proteins; Hippocampus

The Effect of Propofol Anesthesia on Rebound Spiking

The anesthetic propofol potentiates GABAa (inhibitory) receptors in the central nervous system. Paradoxically, low doses of propofol create manifestations of excitation rather than sedation. Previous computational modeling work suggests that postinhibitory rebound spiking may be responsible for this paradoxical excitation. In our models, postinhibitory rebound spiking emerges from an interaction between the inhibitory GABAa current and a slow potassium current (M-current). In contrast to previous studies of postinhibitory rebound spiking, the inhibition is not required to be strong or long. Rather, rebound spiking happens only when the time-constant of inhibition is within a specific range, including relatively fast time-constants. To better understand this phenomenon, we examine rebound spiking in a single model neuron. Fast/slow dynamics are analyzed using techniques from geometric singular perturbation theory. For the transition when the inhibitory time-constant is on the same time scale as the M-current, we use techniques involving the critical manifolds and folded singularities. We show that this technique does not work for the other transition. For the latter, we identify another small parameter, which is the ratio of the two slow time scales. Singular perturbation analysis with this small parameter reveals a different relevant geometric structure. We show how the two geometric structures are related.

Target controlled infusion of Propofol with Remifentanil or Sufentanil for anesthesia with la-ryngeal mask airway ventilation

Objective To evaluate the influence of Remifentanil and Sufentanil on effect of Propofol anesthesia with laryngeal mask airway ventilation. Methods Sixty patients scheduled for elective surgery were randomly divided into propofol group ( group P, n=20 ), propofol with remifentanil group ( group PR, n=20 ) and propofol with sufentanil group ( group PS, n=20 ) .The patients were anesthetized with target controlled infusion of Propofol and RemifentaniK 4 ng/ml) or Sufentanil ( 0.5 ng/ml ).The initial target plasma concentration of Propofol was 2 μ g/ml, and increased step by step until loss of consciousness.The hemodynamic changes and the dosage of Propofol and recovery of anesthesia were observed in all patients.Results Blood pressure was significantly lower in all groups,and HR decreased in PR group after induction of anesthesia(P<0.05 ).Systolic and diastolic blood pressure increased significantly after laryngeal mask airway insertion in group P.The dosage of Propofol required for maintenance of anesthesia in group PR and group PS were reduced by 32.7% and 35.5% respectively.ET-CO2 by spontaneously breathing was higher in the PS group than in group P and group PR when the patients opened their eyes.The times from drug withdrawal to ET-C02 drop to 45mmHg by spontaneously breathing were longer in the PS group than in group P and group PR.Conclusions Remifentanil and sufentanil can reduce significantly the dosage of propofol for anesthesia with laryngeal mask airway ventilation, inhibit the hemodynamic responses to laryngeal mask airway insertion.But the times of laryngeal mask airway extubation could be prolonged by sufentanil during the revitalization of anesthesia. Key words: Propofol; Remifentanil; Sufentanil; Target controlled infusion; Laryngeal mask airway