Antioxidant effects of methylprednisolone and hydrocortisone on the impairment of endothelium dependent relaxation induced by reactive oxygen species in rabbit abdominal aorta / 대한마취과학회지

BACKGROUND: The reperfusion following ischemia produces reactive oxygen species (ROS). We studied the influences of methylprednisolone (MPD) and hydrocortisone (CRT) on ROS effects using the endothelium of rabbit abdominal aorta. METHODS: Isolated rabbit aortic rings were suspended in an organ bath filled with Krebs-Henseleit (K-H) solution. After precontraction with norepinephrine, changes in arterial tension were recorded following the cumulative administration of acetylcholine (ACh). The percentages of ACh-induced relaxation of aortic rings before and after exposure to ROS, generated by electrolysis of K-H solution, were used as the control and experimental values, respectively. The aortic rings were pretreated with MPD or CRT at the same concentrations, and the effects of these agents were compared with the effects of ROS scavenger inhibitors: superoxide dismutase inhibitor, diethylthiocarbamate (DETCA), and the catalase inhibitor, 3-amino-1,2,4-triazole (3AT). RESULTS: Both MPD and CRT maintained endothelium-dependent relaxation induced by ACh in a dose-related manner in spite of ROS attack. The restored ACh-induced relaxation of MPD and CRT group was not attenuated by pretreatment of 3AT and DETCA. CONCLUSIONS: MPD and CRT preserve the endothelium-dependent vasorelaxation against the attack of ROS, in a dose-related manner. Endothelial protection mechanisms of MPD and CRT may be not associated with hydrogen peroxide and superoxide scavenging.

Antioxidant Effect of Captopril and Enalapril on Reactive Oxygen Species-Induced Endothelial Dysfunction in the Rabbit Abdominal Aorta

BACKGROUND: Reactive oxygen species (ROS) are known to be related to cardiovascular diseases. Many studies have demonstrated that angiotensin-converting enzyme inhibitors have beneficial effects against ROS. We investigated the antioxidant effect of captopril and enalapril in nitric oxide mediated vascular endothelium-dependent relaxations. MATERIALS AND METHODS: Isolated rabbit abdominal aorta ring segments were exposed to ROS by electrolysis of the organ bath medium (Krebs-Henseleit solution) after pretreatment with various concentrations (range, 10-5 to 3x10-4 M) of captopril and enalapril. Before and after electrolysis, the endothelial function was measured by preconstricting the vessels with norepinephrine (10-6 M) followed by the cumulative addition of acetylcholine (range, 3x10-8 to 10-6 M). The relevance of the superoxide anion and hydrogen peroxide scavenging effect of captopril and enalapril was investigated using additional pretreatments of diethyldithiocarbamate (DETCA, 0.5 mM), an inhibitor of Cu/Zn superoxide dismutase, and 3-amino-1,2,4-triazole (3AT, 50 mM), an inhibitor of catalase. RESULTS: Both captopril and enalapril preserved vascular endothelium-dependent relaxation after exposure to ROS in a dose-dependent manner (p<0.0001). Pretreatment with DETCA attenuated the antioxidant effect of captopril and enalapril (p<0.0001), but pretreatment with 3AT did not have an effect. CONCLUSION: Both captopril and enalapril protect endothelium against ROS in a dose-dependent fashion in isolated rabbit abdominal aortas. This protective effect is related to superoxide anion scavenging.

Antioxidant effects and mechanism of thiopental and propofol on the rabbit abdominal aortic endothelial dependent vasorelaxation against reactive oxygen species / 대한마취과학회지

No abstract available.

Antioxidant effect of muscle relaxants (vecuronium, rocuronium) on the rabbit abdominal aortic endothelial damage induced by reactive oxygen species / 대한마취과학회지

BACKGROUND: Muscle relaxants induce vascular smooth muscle relaxation by inducing synthesis of the prostaglandins that influence vasomotor tone. However, the effects of muscle relaxants on endothelial cells and tissues following injury by reactive oxygen species (ROS) are unclear. We tested the effects of the muscle relaxants vecuronium and rocuronium on impaired acetylcholine (ACh)-induced relaxation following induction of ROS in rabbit aorta in vitro. METHODS: Isolated rabbit abdominal aortic ring segments were pretreated with vecuronium or rocuronium at 10(-4), 3 x 10(-4), 10(-3) or 3 x 10(-3) M, with or without inhibitors of Cu/Zn superoxide dismutase (diethyldithiocarbamate; DETCA, 0.8 mM) or catalase (3-amino-1,2,4-triazole; 3AT, 50 mM). All groups of aortic rings were then exposed to ROS generated by electrolysis in the organ bath medium (Krebs-Henseleit solution). The effects of vecuronium and rocuronium on ROS-induced impairment of relaxation induced by ACh (10(-6) M) were assessed. RESULTS: Aortic rings treated with vecuronium or rocuronium at 10(-4), 3 x 10(-4), 10(-3) or 3 x 10(-3) M preserved the capacity for ACh-induced endothelial relaxation following ROS exposure in a dose-dependent manner. Pretreatment with DETCA partially inhibited the protective effects of vecuronium and rocuronium on ACh-induced relaxation (P < 0.001), but pretreatment with 3AT had no effect. CONCLUSIONS: Muscle relaxants protected the endothelium in isolated rabbit abdominal aorta from free-radical injury in a dose-dependent manner. These results suggest that vecuronium and rocuronium may act as superoxide anion scavengers.

Comparison of the Pentax AWS and the Glidescope with the Macintosh laryngoscope for tracheal intubation in patients with Mallampati classification I or II

BACKGROUND: The Pentax AWS and the Glidescope are new intubating devices.They were designed to provide a view of the glottis without alignment of the oral, pharyngeal and tracheal axis. The purpose of this study was to evaluate the effectiveness of the Pentax AWS and the Glidescope in comparison with the Macintosh laryngoscope, when performing tracheal intubation in patients with mallampati classification I or II. METHODS: Ninety patients presenting for surgery requiring tracheal intubation, and who were deemed easy for tracheal intubation of mallampati classification I or II were randomly assigned to undergo intubation using a Macintosh (Group M, n = 30), Pentax AWS (Group P, n = 30) or Glidescope (Group G, n = 30). Time to complete tracheal intubation and number of attempts until successful intubation were recorded. Noninvasive blood pressure and heart rate recorded before induction (PI), just before intubation (PT), 1 min and 5 min after intubation. Patients were assessed for postoperative sore throat at 6-12 h after surgery. RESULTS: Time to secure the airway with the Macintosh 13.0 (min 7, max 23.0) s was lesser than with the Pentax AWS 20.4 (8, 51.2) s and Glidescope 22.1 (10, 42.0) s. There were no significant differences in the rate of successful intubations and sore throat among the groups. There were significant increases in both mean arterial pressure and heart rate 1 min after intubation in all groups compare with PI. CONCLUSIONS: The Pentax AWS and the Glidescope had no specific advantage over the Macintosh laryngoscope for the patients with normal airway.

Effect of ketorolac and diclofenac on the impairment of endothelium-dependent relaxation induced by reactive oxygen species in rabbit abdominal aorta / 대한마취과학회지

BACKGROUND: Reactive oxygen species (ROS) induce lipid peroxidation and tissue damage in endothelium. We studied the influences of ketorolac and diclofenac on ROS effects using the endothelium of rabbit abdominal aorta. METHODS: Isolated rabbit aortic rings were suspended in an organ bath filled with Krebs-Henseleit (K-H) solution bubbled with 5% CO2 and 95% O2 at 37.5degrees C. After being stimulated to contract with phenylephrine (PE, 10(-6) M), changes in arterial tension were recorded following the cumulative administration of acetylcholine (ACh, 3 x 10(-8) to 10(-6) M). The percentages of ACh-induced relaxation of aortic rings before and after exposure to ROS, generated by electrolysis of K-H solution, were used as the control and experimental values, respectively. The aortic rings were pretreated with ketorolac or diclofenac at the same concentrations (10(-5) M to 3 x 10(-4) M), and the effects of these agents were compared with the effects of ROS scavengers: catalase, mannitol, sodium salicylate and deferoxamine and the catalase inhibitor, 3-amino-1,2,4-triazole (3AT). RESULTS: Both ketorolac and diclofenac maintained endothlium-dependent relaxation induced by ACh in a dose-related manner inspite of ROS attack (P < 0.05 vs. control value). The 3AT pretreated ketorolac (3 x 10(-3) M) group was decreased more significantly than un-pretreated ketorolac (P < 0.05). CONCLUSIONS: These findings suggest that ketorlac and diclofenac preserve the endothelium-dependent vasorelaxation against the attack of ROS, in a concentration-related manner. One of the endothelial protection mechanisms of ketorolac may be hydrogen peroxide scavenging.

Antioxidant effect of lidocaine and procaine on reactive oxygen species-induced endothelial dysfunction in the rabbit abdominal aorta / 대한마취과학회지

BACKGROUND: Reactive oxygen species (ROS) induce lipid peroxidation and tissue damage in the endothelium. We tested the antioxidant effect of lidocaine and procaine on ROS-induced endothelial damage in the rabbit aorta. METHODS: Aortic rings isolated from rabbits were suspended in an organ bath filled with Krebs-Henseleit (K-H) solution bubbled with 5% CO2 and 95% O2 at 37.5degrees C. After precontraction with phenylephrine (PE, 10(-6) M), changes in tension were recorded following a cumulative administration of acetylcholine (ACh 3 x 10(-8) to 10(-6) M). Differences were measured as percentages of ACh-induced relaxation of aortic rings before and after exposure to ROS as generated by electrolysis of the K-H solution. The aortic rings were pretreated with lidocaine or procaine (10(-5) M to 3 x 10(-3) M) to compare their effects, as well as ROS scavengers, catalase, mannitol, sodium salicylate, and deferoxamine, and a catalase inhibitor, 3-amino-1,2,4-triazole (3AT). RESULTS: Lidocaine and procaine dose-dependently maintained endothelium-dependent relaxation induced by ACh despite ROS activity (P < 0.05 vs control value). The 3AT pretreated procaine (3 x 10(-3) M) group decreased more significantly than the un-pretreated procaine group (P < 0.05). CONCLUSIONS: These findings suggest that lidocaine and procaine dose-dependently preserve endothelium-dependent vasorelaxation against ROS attack, potentially via hydrogen peroxide scavenging.

Irregular antibody found during emergency subarachnoid hemorrhage operation : A case report

Irregular or unexpected antibodies are alloantibodies against serum or red blood cells after previous exposure to transfusion. When encountered in critical condition, however, risk of ongoing complication is not entirely predictable. Rapid transfusion of safe blood is thus, crucial not to compromise further procedure. A 78-year-old ASA IV man presented with Hunt-Hess grade IV subarachnoid hemorrhage with huge temporal bleeds. While in operating room, his blood pressure dropped when the dura was opened. Meanwhile, routine screening of blood typing repeatedly denoted Rh+O with irregular antibodies. Soon, compatible cross-matched blood was infused with 37 degrees C normal saline 200 ml at a rate of 4-5 ml/kg/hr. There was no laboratory evidence of hemolytic transfusion reaction. Postoperatively, BUN and creatinine increased slightly, but urination and respiration were unremarkable.

Correlation between actual measurement and estimation by hemoglobin dilution method

BACKGROUND: Hemoglobin dilution occurs after acute blood loss, by shifting extravascular blood components into the intravascular space, providing the theoretical possible to calculate amount of blood loss by comparing this difference.Assessing blood loss during the operative procedure is crucial to provide appropriate treatment, however there are few objective standards by which to make this assessment.In this study, we used the hemoglobin dilution method to predict blood loss following an operative procedure. METHODS: During the year 2007, 96 patients who had undergone lumbar spinal fusion surgery were enrolled in this study.On a retrospective basis, we investigated the weight, height, intraoperative blood loss, hemoglobin change, and the amount of transfused erythrocytes by reviewing anesthetic notes from the surgery. On the basis of these data, we calculated estimated blood loss by using Nadler's formula. RESULTS: The majority of study participants were female and average age was 60.1 yrs.We observed 2.3 g/dl decrement of postoperative hemoglobin, and estimated blood volume was 3,599 ml. Estimated blood loss was 853.7 ml, and observed blood loss was 1,070 ml, thus creating 217.1 ml difference.Analysis showed a moderate degree of correlation between observed and estimated values and a correlation coefficient of 0.49. We obtained regression equations of y = 0.828x + 363.5. CONCLUSIONS: Estimated blood loss was underestimated compared to observed values, by 20%, and this discrepancy is was attributed to ethnic differences. To predict a precise estimated blood loss, attempts to make a modified formula targeted to the Korean population are required.

Randomized Study Comparing the Sniffing Position with the Neutral Position for Lightwand Intubation / 대한마취과학회지

BACKGROUND: The sniffing position is recommended for optimal glottic visualization under direct laryngoscopy. However, there is no study assessing whether sniffing position is superior to a neutral position during lightwand-guided intubation. This prospective, randomized study was performed to compare facilitation of lightwand-guided intubation between the sniffing and neutral positions. METHODS: The study included 180 patients with normal cervical spines requiring tracheal intubation for elective surgery. Patients were randomly allocated into two groups: neutral or sniffing position. Mallampati class, mouth opening distance, thyromental distance, and laryngeal view grade were measured. A lightwand railroaded with an endotracheal tube was bent 90degrees at 5 cm from the distal end for both groups. Time to intubation, success rate and intubation time for the first attempt, hydrodynamic changes, and BIS values were recorded. RESULTS: There were no significant differences in time to intubation, success rate and intubation time of the first trial, hydrodynamic changes, or BIS values between the two positions. CONCLUSIONS: Routine use of the sniffing position does not provide any advantage over the neutral position during lightwand-guided intubation.

Negative-pressure Pulmonary Edema by Doxapram-induced Larygospasm: A case report / 대한마취과학회지

Doxapram is a peripheral and central respiratory stimulant, producing an increase in tidal volume and a slight increase in respiratory rate. It can temporarily overcome drug-induced respiratory and central nervous system depression, including that seen immediately postoperatively. However, it can also cause side effects, including laryngospasm and vomiting postoperatively. Doxapram-induced laryngospasm causes the increased respiratory efforts to induce more negative pleural pressure, thus causing a negative-pressure pulmonary edema.Therefore, doxapram should not be used if signs of upper airway obstruction are present.

Tumor Induced Disseminated Intravascular Coagulation : A case report

Neuroblastoma, relatively common pediatric nervous system malignancy, presents as in various clinical aspects, including mass, pain, fever, weight loss, and infrequently anemia and hepatopathy. Hematologic abnormalities are also brought about according to the disease stage or pancytopenia due to radiation, mainly in the form of coagulopathy. We herein briefly report a rare case of stage IV neuroblastoma accompanied by chronic or subacute disseminated intravascular coagulation in a 5-year-old boy. Despite apparently normal coagulation profiles, we could not conduct routine invasive vascular procedures after induction of general anesthesia because of unexplained bleeding diathesis. Anesthesiologists should be alert to this kind of unexpected but potentially lethal complication and prepare to avoid mishaps.

The Assessment of Postoperative Nausea and Vomiting (PONV) using Rhodes Index in PONV High Risk Group / 대한마취과학회지

BACKGROUND: The Rhodes index of nausea, vomiting and retching (RINVR) is a reliable and valid instrument to assess PONV. The purpose of this study was to investigate the incidence of PONV in high risk group with using RINVR. METHODS: Patients scheduled for elective surgery under general anesthesia were classified in three groups (group I:two risk factors, group II:three risk factors, group III:four risk factors) by using a simplified risk score.We investigated the incidences of PONV in each group. RESULTS: The incidence of PONV was 12.8% in group I, 25% in group II, and 33.1% in group III, which showed a significant difference between group I and group II, between group I and group III.The incidence of PONV, which was over moderate was significantly increased in group III. CONCLUSIONS: For patients with three or four risk factors a multimodal antiemetic strategy should be considered.

Vital Sign Change after Placement in the Prone Position in an Obese Patient: A case report / 대한마취과학회지

When performing spine surgery, placement of the patient in the prone position with longitudinal padding is most frequently utilized.However, hemodynamics could be compromised by compression of the internal organs, particularly if surgery is being conducted on an morbidly obese patient or on a patient with a soft frame.An increase in the intraabdominal and intrathoracic pressure might cause a perfusion defect of major venous return, a decrease in cardiac output and a defect in pulmonary ventilation and venous congestion within the spinal canal.Accordingly, serious alteration of vital signs or significant expected consequences can occur.We briefly report a case of life-threatening hemodynamic change after placement in the prone position of a morbidly obese patient during general anesthesia.Placing a risky patient on a semi-rigid, stable Wilson frame can be a promising alternative to avoid such intraoperative mishaps.

Effects of Steroid Administration on the Blood Glucose Level during Spine Surgery in Patients with Metabolic Syndrome

BACKGROUND: The risk of steroid-induced hyperglycemia is debated, and methylprednisolone is still used during spinal surgery. We have compared the blood glucose level in patients with metabolic syndrome treated with or without methylprednisolone. METHODS: This study was conducted in 68 adult patients who underwent elective spine surgery. Patients were classified into the following groups: methylprednisolone group (n = 39, group M), placebo group (n = 29, group P), group M patients with metabolic syndrome (n = 17, group MM), and group P patients without metabolic syndrome (n = 21, group NMP). Before and after injection of either 125 mg methylprednisolone or a placebo, we consecutively checked the blood glucose level every 30 minutes up to 4 hours. RESULTS: The blood glucose level was significantly increased in group M patients as compared to group P patients. The blood glucose level was more significantly increased in group MM as compared to group NMP patients. The increased blood glucose levels over 4 hours were 50 mg/dl in group MM and 35 mg/dl in group NMP patients. CONCLUSIONS: We recommend that close monitoring of the blood glucose level up to several hours after injection of a steroid should be seriously considered during spine surgery, particularly in patients with metabolic syndrome.

Effect of Intravenous Propofol and Fentanyl on Bispectral Index Changes during Endotracheal Suction in ICU Conscious Patient / 대한마취과학회지

BACKGROUND: We performed a prospective, randomized, and controlled trial to evaluate the effect of an intravenous fentanyl and propofol on the variation in BIS level associated tracheal suction. METHODS: Thirty ICU patients intubated or tracheostomized were randomly allocated to control and experimental groups. Control group was received saline and experimental groups were received propofol with or without fentanyl intravenously prior to tracheal suction. And then we monitored BIS index, blood pressure, heart rate and SpO2 before, during and after tracheal suction. RESULTS: BIS index was significantly lower in propofol plus fentanyl group than others during experiment (P < 0.05). Heart rate and blood pressure in propofol plus fentanyl group also less increased than those in control or propofol group during tracheal suction (P < 0.05). CONCLUSIONS: These results suggest that co-administration of propofol and fentanyl has more effective than propofol alone in sedation and analgesia of ICU patients during tracheal suction.

Effects of Steroid Administration on Blood Glucose Concentration during Brain Surgery / 대한마취과학회지

BACKGROUND: Steroids are normally used in neurosurgery, especially when treating brain edema and reducing the intracranial pressure. Methylprednisolone is known to increase the blood glucose concentration. However, the effect of a single methylprednisolone injection on the blood glucose concentration is unknown. Therefore, this study measured and compared the blood glucose concentration in a methylprednisolone group with that in a placebo group at the same interval. METHODS: Thirty-three adult patients were enrolled in this study. The patients were scheduled to undergoing an elective craniotomy with the procedure lasting 4 hours or longer. The candidates were divided in two groups. One group was the methylprednisolone group (patients receiving methylprednisolone 125 mg, n = 18), and the other group was the placebo group (n = 15). The exclusion criteria were a clinical diagnosis of diabetes mellitus, an impaired glucose tolerance and had received steroid previously. Before injecting 125 mg of either methylprednisolone or the placebo, the blood glucose concentration was checked by glucose analyzer. After the injection, blood glucose concentration was checked every 30 minutes for more than 4 hours. RESULTS: The blood glucose concentration increased significantly over time compared with the baseline concentration in both groups. The glucose concentration increased significantly in the methylprednisolone group than in the placebo group (P < 0.05). The magnitude of this difference was greater in those who received methylprednisolone (54 mg/dl increase over 4 hours) than in the placebo group (11 mg/dl increase over 4 hours). CONCLUSIONS: In this study, compared with placebo controls, an injection of methylprednisolone (125 mg) produced a significant increase in the blood glucose concentration over a 4 hours period. Therefore, we recommend that the blood glucose level be monitored carefully in cases of brain surgery and/or when steroids are used.

Effect of Thiopental and Ketamine on Endothelium-Dependent Relaxation Induced by Reactive Oxygen Species in Rabbit Thoracic Aorta / 대한마취과학회지

BACKGROUND: Reactive oxygen species (ROS) are free radicals that induce lipid peroxidation and cause tissue damage. ROS are frequently produced by ischemia and subsequent reperfusion in clinical situation and like coronary artery bypass graft surgery and transplantation. More over, some anesthetics are known to act as an antioxidants and free radical scavenger and, the aim of this study was to explore the scavenging effects of thiopental and ketamine against ROS induced by isolated rabbit thoracic aortic endothelial damage. METHODS: Twenty white male rabbits (weighing 2.0-2.5 kg) were used. Thoracic aorta and were dissected free, cut into rings (3-4 mm), and suspended in an organ bath filled with 10 ml Krebs solution bubbled with 5% CO2 and 95% O2 at 37oC. The rings were equilibrated for 90 min and the solution changed every 15 min, and then a resting tension of 1.5 g was applied to the rings. Isometric tensions were recorded using a transducer connected to a data acqusition system (Biopac Inc. USA). Aortic rings were precontracted with norepinephrine (NE, 10-6 M), and changes in tension were measured after the cumulative administration of acetylcholine (ACh 3 x 10-7, 10-6 and 3 x 10-6 M) and nitroglycerin (NTG 10-5 M). Data are expressed as percentages of the 10-5 M NTG-induced relaxation (ACh/NTG). Percentages of ACh/NTG, before and after ROS exposure by electrolysis were noted for control and experimental groups. Aortic rings were pretreated with thiopental (3 x 10-5, 10-4 and 3 x 10-4 M, n = 9, 13, 17), ketamine (10-4 M, n = 8), catalase (1000 U/ml, n = 12), mannitol (3 x 10-4 M, n = 5) or not pretreated (free, n = 6). After 30 minutes, with the rings were exposed to ROS by electrolysis (DC 9 V, 20 mA, aortic rings 1 cm removed from the anode) in Krebs solution for 2 minutes. After electrolysis, the organ bath fluid was replaced with fresh Krebs solution, and the aortic rings were precontracted with NE and was vasorelaxation with ACh and NTG as above mentioned concentrations. RESULTS: Endothelium-dependent vasorelaxation was induced in all concentrations of thiopental groups in a dose-dependent fashion (P <0.05 vs control value) even with ROS attack. The catalase group produced vasorelaxation after ROS attack (P <0.05 vs control value). On the other hand, no ACh-induced significant endothelium-dependent vasorelaxation after ROS exposure was observed in the ketamine and mannitol pretreated group, or in the free group (P <0.05 vs control group). CONCLUSIONS: These findings suggest that thiopental and catalase preserve ACh induced endothelium-dependent vasorelaxation and that thiopental has a dose-dependent ROS scavenging effect like catalase.

Genotoxicity of Enflurane in Human Peripheral Blood Lymphocytes Studied in vivo by Single Cell Gel Electrophoresis / 대한마취과학회지

BACKGROUND: The alkaline single cell gel electrophoresis comet assay was applied to study the genotoxic properties of enflurane on the human peripheral blood lymphocytes (PBL) of cancer patients before and during anesthesia as compared to an non-cancer control group. Method: The cancer group consisted of 24 patients (aged 15-77 years), while the control group consisted of 14 trauma individuals (aged 20-81 years). After anesthesia induction (thiopental 4 mg/kg and vecuronium 0.1 mg/kg), it was maintained by enflurane inhalation; 1-2 minimal alveolar concentration in oxygen - nitrous oxide mixture. Venous blood samples were obtained before the induction of anesthesia, and after 60 and 120 min of anesthesia. The comet assay detects DNA damage, such as strand breaks and alkaline labile sites induced directly by genotoxic agents, and DNA degradation due to cell death. Fifty cells from each sample were examined and Olive tail moments (OTM) were calculated using Komet 4TM software. RESULTS: OTM values were no different between controls and patients before anesthesia. However, the OTMs of blood sampled from cancer patients at 60 (7.97 +/- 1.83) and 120 min (7.86 +/- 2.05), and from trauma patients at 120 min (8.04 +/- 1.32) of anesthesia were significantly increased. CONCLUSIONS: In immunocompromised cancer patients, we suggest the existence of a higher risk of an association DNA damage and enflurane exposure.

Protective Effect of Propofol on Endothelial Damage Induced by Reactive Oxygen Species in Rabbit / 대한마취과학회지

BACKGROUND: Reactive oxygen species (ROS) induce lipid peroxidation and tissue damage in the isolated rabbit thoracic aorta. The aim of this study was to explore the influence of the propofol and midazolam against ROS in the isolated rabbit thoracic aortic endothelium. METHODS: Eighteen white male rabbits (weighing 2.0-2.5 kg) were used. The thoracic aorta was dissected free and cut into rings (3-4 mm) and then suspended in a organ bath filled with 10 ml Krebs solution bubbled with 5% CO2 95% O2 at 37 degrees C. Aortic rings were then equilibrated for 90 min, and a resting tension of 1.5 g was applied. The Krebs solution was changed every 15 min. Isometric tension was recorded with transducer coupled to a data acqusition system (Biopac Inc. USA) on a PC. After precontraction with norepinephrine (NE, 10(-6)M), changes in tension were measured following the cumulative administration of acetylcholine (ACh 3x10(-7), 10(-6) and 3x10(-6)M) and nitroglycerin (NTG, 10(-5)M). Data are expressed as percentage of the 10 5 M NTG-induced relaxation (ACh/NTG). The ACh/NTG, before and after electrolysis were defined as the control and the experimental groups. The aortic rings were pretreated with propofol (3x10(-5), 10(-4), 3x10(-4) and 5.7x10(-4) M, n = 8, 10, 15, 13), midazolam (10(-4)M, n = 7), catalase (1,000 U/ml, n = 12), mannitol (3x10(-4)M, n = 5) or not pretreated group (Free, n = 6). After 30 minutes, the aortic rings were exposed to ROS generated by electrolysis (DC 9 V, 20 mA, aortic rings 1 cm away from electrode) in Krebs solution for 2 minutes, which was then changed for physiologic buffered salt solution. The aortic rings were precontracted with NE and vasorelaxation was induced with ACh and NTG at the above mentioned concentrations. RESULTS: Propofol produced vasorelaxation of NE-precontracted thoracic aorta in a dose-dependent fashion in all groups of propofol (3x10(-5), 10(-4), 3x10(-4) and 5.7x10(-4)M) even after ROS attack (P < 0.05 vs control value). Catalase produced vasorelaxation after ROS attack (P < 0.05 vs control value).On the other hand, ACh-induced significant endothelium-dependent vasorelaxation were not observed in the midazolam or mannitol pretreated group or the non-pretreated group (P <0.05 vs control group). CONCLUSIONS: These findings suggest that propofol and catalase preserve ACh induced endothelium-dependent vasorelaxation and that propofol has a concentration dependent ROS scavenging effect like catalase.