The Intracisternal Administration of MEK Inhibitor Attenuates Mechanical and Cold Allodynia in a Rat Model of Compression of the Trigeminal Ganglion

The present study investigated the role of ERK in the onset of mechanical and cold allodynia in a rat model of compression of the trigeminal ganglion by examining changes in the air-puff thresholds and number of scratches following the intracisternal injection of PD98059, a MEK inhibitor. Male Sprague Dawley rats weighing between 250 and 260 g were used. Under anesthesia, the rats were mounted onto a stereotaxic frame and received 4% agar (10 microl) solution to compress the trigeminal ganglion. In the control group, the animals were given a sham operation without the application of agar. Changes in behavior were examined at 3 days before and at 3, 7, 10, 14, 17, 21, 24, 30, and 40 days after surgery. Compression of the trigeminal ganglion significantly decreased the air-puff thresholds. Mechanical allodynia was established within 3 days and persisted over postoperative day 24. To evaluate cold allodynia, nociceptive scratching behavior was monitored after acetone application on the vibrissa pad of the rats. Compression of the trigeminal ganglion was found to produce significant cold allodynia, which persisted for more than 40 days after surgery. On postoperative day 14, the intracisternal administration of 1 microg or 10 microg of PD98059 in the rat model significantly decreased the air-puff thresholds on both the ipsilateral and contralateral side. The intracisternal administration of 10 microg of PD98059 also significantly alleviated the cold allodynia, compared with the vehicle-treated group. These results suggest that central ERK plays an important role in the development of mechanical and cold allodynia in rats with compression of the trigeminal ganglion and that a targeted blockade of this pathway is a potential future treatment strategy for trigeminal neuralgia-like nociception.

A Blockade of the Central MAPK Pathway Attenuates Referred Pain in Rats with Complete Freund's Adjuvant-Induced Inflammation of the Temporomandibular Joint

We investigated the role of the central MAPK pathways in extra-territorial (referred) pain resulting from inflammation of the temporomandibular joint (TMJ). Experiments were carried out on male Sprague-Dawley rats weighing 220-280 g. Under anesthesia, these animals were injected with 50 microL of complete Freund's adjuvant (CFA) into the TMJ using a Hamilton syringe. In the control group, saline was injected into the TMJ. To identify the extent of inflammation of the TMJ, Evans blue dye (0.1%, 5 mg/kg) was injected intravenously at 1, 3, 6, 9, 12 and 15 days after CFA injection. The concentration of Evans blue dye in the extracted TMJ tissue was found to be significantly higher in the CFA-treated animals than in the saline-treated group. Air-puff thresholds in the vibrissa pad area were evaluated 3 days before and at 3, 6, 9, 12, 15 and 18 days after CFA injection into the TMJ. Referred mechanical allodynia was established at 3 days, remained until 12 days, and recovered to preoperative levels at 18 days after CFA injection. This referred mechanical allodynia was observed in contralateral side area. To investigate the role of central MAPK pathways, MAPK inhibitors (10 microg) were administrated intracisternally 9 days after CFA injection. SB203580, a p38 MAPK inhibitor, significantly attenuated referred mechanical allodynia, as compared with the vehicle group. PD98059, a MEK inhibitor, also reduced CFA-induced referred mechanical allodynia. These results suggest that TMJ inflammation produces extra-territorial mechanical allodynia, and that this is mediated by central MAPK pathways.

Role of the PLA2-Activated Neutrophilic Oxidative Stress in Oleic Acid-Induced Acute Lung Injury / 결핵및호흡기질환

BACKGROUND: The underlying pathogenesis of fat embolism-induced acute lung injury (ALI) has not been elucidated. In the present study, the pathogenesis of fat embolism-induced ALI was probed in association with neutrophilic oxidative stress in oleic acid (OA)-induced ALI of S-D rats. METHODS: OA was injected intravenously to provoke ALI in experimental rats. Five hours later, indices of ALI were measured to confirm the role of the neutrophilic respiratory burst. The effect of an inhibition of phospholipase A2 (PLA2) was also evaluated. RESULTS: The accumulation of neutrophils in the lung due to OA caused increased neutrophilic oxidative stress in lung, which was ameliorated by mepacrine. What were the results from inhibition of PLA2. CONCLUSION: Excess neutrophilic oxidative stress contributes to OA-induced ALI, which is lessened by the inhibition of PLA2.

Ischemia/reperfusion Lung Injury Increases Serum Ferritin and Heme Oxygenase-1 in Rats

Intestinal ischemia/reperfusion (I/R) is one of common causes of acute lung injury (ALI). Early and accurate diagnosis of patients who are like to develop serious acute respiratory distress syndrome (ARDS) would give a therapeutic advantage. Ferritin and heme oxygenase-1 (HO-1) are increased by oxidative stress and are potential candidates as a predictive biomarker of ARDS. However, the mechanisms responsible for the increases of ferritin and HO-1, and their relationship to ALI, are unclear. In order to elucidate the interactions between ferritin and HO-1, we studied the changes in ferritin and HO-1 levels in serum and bronchoalveolar lavage (BAL) fluid after intestinal I/R injury in rats. Leukocyte number and protein contents in BAL fluid were elevated following I/R, and the increases were attenuated by mepacrine pretreatment. Both serum ferritin and HO-1 concentrations were progressively elevated throughout the 3 h observation period. Mepacrine pretreatment attenuated the increase of serum and BAL fluid ferritin concentrations, but did not suppress the increase of serum HO-1. Moreover, BAL fluid HO-1 levels did not change after I/R or after mepacrine pretreated I/R compared with sham rats. Unlike ferritin, HO-1 levels are not exactly matched with the ALI. Therefore, there might be a different mechanism between the changes of ferritin and HO-1 in intestinal I/R-induced ALI model.

Changes of Serum Ferritin in Acute Lung Injury Induced by Intestinal Ischemia/Reperfusion

Serum ferritin levels are increased in subjects at-risk for or with acute lung injury (ALI), and there are observations to suggest that increases in serum ferritin levels may help predict the development of ALI in at-risk individuals. To deepen our understanding of increases of serum ferritin and their relationship to the development of ALI, we measured serum ferritin levels before and after intestinal ischemia/reperfusion (I/R) injury in rats, and found that serum ferritin levels increased significantly following I/R. Increases in serum and lavage ferritin levels paralleled increases in lung inflammation (lavage leukocyte numbers and tissue myeloperoxidase activities) and lung leak (lavage protein levels). In contrast, pre-treatment of rats with mepacrine (60 mg/kg, i.p.), a phospholipase A2 inhibitor, attenuated not only I/R-induced serum and lavage ferritin increases, but also the development of ALI. These findings indicate that, besides of human subjects with ALI, serum ferritin levels increase early on also in an animal model of ALI. Therefore, serum and lavage ferritin can be a candidate for early biomarker of ALI.

Effects of Aspirin on the Pathogenesis of Acute Lung Injury in Rats Subjected to Hemorrhage / 결핵및호흡기질환

BACKGROUND: For unknown reasons, the serum ferritin concentrations are higher in patients with acute lung injury. A pretreatment with aspirin reduces the acute lung injury in rats subjected severe hemorrhage, and increases the rate of ferritin synthesis in vitro. This study investigated the effect of aspirin on the serum ferritin changes in rats subjected to severe hemorrhage. METHODS: Hemorrhagic shock was induced by withdrawing blood (20 ml/kg of B.W.) through the femoral artery for 5 min. The rats were pretreated with aspirin (10 mg/kg, i.v.) 30 min before hemorrhage. RESULTS: The protein content and leukocyte count in the bronchoalveolar lavage fluid, lung tissue myeloperoxidase activities were significantly higher after hemorrhage. The aspirin pretreatment prevented these changes. The serum and lavage fluid ferritin concentrations were elevated higher after hemorrhage. These were also attenuated by the aspirin pretreatment. CONCLUSION: The changes in the serum and lung lavage ferritin level might be closely related to the severity of hemorrhage?induced acute lung injury. Therefore, the serum and lavage ferritin concentrations can be a useful biomarker for patients with precipitating conditions.

Effects of Aspirin on the Pathogenesis of Acute Lung Injury in Rats Subjected to Hemorrhage / 결핵및호흡기질환

BACKGROUND: For unknown reasons, the serum ferritin concentrations are higher in patients with acute lung injury. A pretreatment with aspirin reduces the acute lung injury in rats subjected severe hemorrhage, and increases the rate of ferritin synthesis in vitro. This study investigated the effect of aspirin on the serum ferritin changes in rats subjected to severe hemorrhage. METHODS: Hemorrhagic shock was induced by withdrawing blood (20 ml/kg of B.W.) through the femoral artery for 5 min. The rats were pretreated with aspirin (10 mg/kg, i.v.) 30 min before hemorrhage. RESULTS: The protein content and leukocyte count in the bronchoalveolar lavage fluid, lung tissue myeloperoxidase activities were significantly higher after hemorrhage. The aspirin pretreatment prevented these changes. The serum and lavage fluid ferritin concentrations were elevated higher after hemorrhage. These were also attenuated by the aspirin pretreatment. CONCLUSION: The changes in the serum and lung lavage ferritin level might be closely related to the severity of hemorrhage?induced acute lung injury. Therefore, the serum and lavage ferritin concentrations can be a useful biomarker for patients with precipitating conditions.

Aspirin Reduces Acute Lung Injury in Rats Subjected to Severe Hemorrhage / 결핵

BACKGROUND: Hemorrhagic shock and trauma are two of the most common causes of acute lung injury. The activation of cyclooxygenase is one of the important causes of acute lung injury. This study investigated the effect of aspirin, a well-known cyclooxygenase inhibitor, on severe hemorrhage-induced acute lung injury in rats. METHODS: The hemorrhagic shock was induced by withdrawing blood; 20ml/kg of B.W., through the femoral artery in 5 min. The mean arterial pressure was recorded through the femoral artery on a polygraph. RESULTS: In the present investigation, the lung tissue myeloperoxidase activity, protein contents and leukocyte counts, in bronchoalveolar lavage fluid, increased significantly 2 and 24 h after the hemorrhage induction. Although the decreased mean arterial pressure spontaneously recovered, acute lung injury occurred after severe hemorrhage. These changes were effectively prevented by a single intravenous injection of aspirin (10 mg/kg of B.W.) 30 min before the hemorrhage. CONCLUSION: These results suggest that severe hemorrhage-induced acute lung injury is mediated, in part, by the activation of cyclooxygenase. Furthermore, pretreatment of aspirin in acute lung injury-prone patients, or prophylactic treatment of aspirin to the patients with precipitating conditions, could be helpful in the prevention of acute lung injury.

Effect of the inhibition of PLA2 and PAF on the neutrophilic respiratory burst and apoptosis / 결핵

BACKGROUND: Since the exact pathogenesis of sepsis-induced ARDS has not been elucidated, the mechanisms of enhanced neutrophilic respiratory burst were probed in endotoxin primed neutrophils associated with the roles of phospholipase A2 (PLA2), platelet activating factor (PAF) and apoptosis. METHODS: In isolated fresh human neutrophils, effects of the inhibition of PLA2 and PAF on the apoptosis were examined by the method of Annexin-FITC/dual PI flow cytometry. The roles of PLA2 and PAF on the neutrophilic respiratory burst were also examined by measuring oxidant generation in cytochrome-c reduction assay. Activities of the PLA2 and lysoPAF acetyltransferase (lysoPAF AT) of the neutrophils were determined to understand the effect of endotoxin on these enzymatic activities which may be related to the neutrophilic respiratory burst and apoptosis. In addition, the role roles of PLA2 and PAF in neutrophilic adhesion to bovine endothelial cells were examined in vitro by neutrophil adhesion assay. To investigate the effect of oxidants on pulmonary surfactant, cytochemical ultrastructural microscopy was performed. To inhibit PLA2 and PAF, non-specific PLA2 inhibitor mepacrine (100 nM) and WEB 2086 (100 nM) or ketotifen fumarate (10 kg/ml) were used respectively in all in vitro experimental sets. WEB 2086 is PAF receptor antagonist, and ketotifen fumarate is a lyso PAF AT inhibitor. RESULTS: The mapacrine treatment, provided after the endotoxin (ETX) treatment, resulted in increased apoptosis of neutrophils (p<0.001) while treatments of WEB 2086 and ketotifen did not. The inhibition of PLA2 and PAF decreased (p<0.001) production of oxidants from PMA-stimulated neutrophils. While endotoxin increased the PLA2 activity of neutrophils (p<0.01), mepacrine supressed (p<0.001) the activity, provided after treatment of ETX. The lyso PAF actyltransferase activity (lyso PAF AT) increased(p<0.01) after treatment of ETX. In contrast, mepacrine, WEB 2086 and ketotifen showed a tendency of decreasing the activity after treatment of ETX. The Treatment of ETX increased (p<0.001) neutrophil adhesion to endothelial cells, which was reversed by inhibition of PLA2 and PAF (p<0.001). The binding of oxidants to pulmonary surfactant was identified histologically. CONCLUSIONS: The enhanced neutrophilic respiratory burst by ETX plays a pivotal role in the pathogenesis of ARDS in term of oxidayive oxidative stress. Increased production of oxidants form neutrophils is mediated by the activations of PLA2 and lyso PAF AT.

Effect of the inhibition of phospholipase A2 in generation of free radicals in intestinal ischemia/reperfusion induced acute lung injury

The role of phospholipase A2 (PLA2) in acute lung leak induced by intestinal ischemia was investigated in association with neutrophilic respiratory burst. To induce lung leak, we generated intestinal ischemia for 60 min prior to the 120 min reperfusion by clamping superior mesenteric artery in Sprague-Dawley rats. Acute lung leak was confirmed by the increased lung leak index and protein content in bronchoalveolar fluid. These changes were inhibited by mepacrine, the non-specific PLA2 inhibitor. The lung myeloperoxidase (MPO) activity denoting the pulmonary recruitment of neutrophils was increased by intestinal I/R, but decreased by mepacrine. Simultaneously, the number of leukocytes in bronchoalveolar fluid was increased by intestinal ischemia/reperfusion (I/R) and decreased by mepacrine. Gamma glutamyl transferase activity, an index of oxidative stress in the lung, was increased after intestinal I/R but decreased by mepacrine, which implicates that PLA2 increases oxidative stresscaused by intestinal I/R. The PLA2 activity was increased after intestinal I/R not only in the intestine but also in the lung. These changes were diminished by mepacrine. In the cytochemical electron microscopy to detect hydrogen peroxide, intestinal I/R increased the generation of the hydrogen peroxide in the lung as well as in the intestine. Expression of interleukin-1 (IL-1) in the lung was investigated through RT-PCR. The expression of IL-1 after intestinal I/R was enhanced, and again, the inhibition of PLA2 suppressed the expression of IL-1 in the lung. Taken together, intestinal I/R seems to induce acute lung leak through the activation of PLA2, the increase of IL-1 expression associated with increased oxidative stress by neutrophilic respiratory burst.

PAF contributes to intestinal ischemia/reperfusion-induced acute lung injury through neutrophilic oxidative stress

The role of platelet-activating factor (PAF) was investigated in intestinal ischemia/reperfusion (I/R) induced acute lung injury associated with oxidative stress. To induce acute lung injury following intestinal I/R, superior mesenteric arteries were clamped with bulldog clamp for 60 min prior to the 120 nun reperfusion in Sprague-Dawley rats. Acute lung injury by intestinal I/R was confirmed by the measurement of lung leak index and protein content in bronchoalveolar lavage (BAL) fluid. Lung leak and protein content in BAL fluid were increased after intestinal I/R, but decreased by WEB 2086, the PAF receptor antagonist. Furthermore, the pulmonary accumulation of neutrophils was evaluated by the measurement of lung myeloperoxidase (MPO) activity and the number of neutrophils in the BAL fluid. Lung MPO activity and the number of neutrophils were increased (p<0001) by intestinal I/R and decreased by WEB 2086 significantly. To confirm the oxidative stress induced by neutrophilic respirat ory burst, gamma glutamyl transferase (GGT) activity was measured. Lung GGT activity was significantly elevated after intestinal I/R (p<0.001) but decreased to the control level by WEB 2086. On the basis of these experimental results, phospholipase A2 (PLA2), lysoPAF acetyltransferase activity and PAF contents were measured to verify whether PAF is the causative humoral factor to cause neutrophilic chemotaxis and oxidative stress in the lung following intestinal I/R. Intestinal I/R greatly elevated PLA2 activity in the lung as well as intestine (p<0.001), whereas WEB 2086 decreased PLA2 activity significantly (p<0.001) in both organs. LysoPAF acetyltransferase activity, the PAF remodelling enzyme, in the lung and intestine was increased significantly (p<0.05) also by intestinal I/R. Accordingly, the productions of PAF in the lung and intestine were increased (p<0.001) after intestinal I/R compared with sham rats. The level of PAF in plasma was also increased (p<0.05) followin g intestinal I/R. In cytochemical electron microscopy, the generation of hydrogen peroxide was increased after intestinal I/R in the lung and intestine, but decreased by treatment of WEB 2086 in the lung as well as intestine. Collectively, these experimental results indicate that PAF is the humoral mediator to cause acute inflammatory lung injury induced by intestinal I/R.

Nitric oxide impairs the recovery from hemorrhagic hypotension in conscious rats

The role of nitric oxide (NO) in the hemorrhagic hypotension was examined using a NO synthase inhibitor, Nomega-nitro-L-arginine methyl ester (L-NAME), in conscious rats, The rats were bled at a constant rate (2 ml/kg/min) through a femoral arterial catheter until the mean arterial pressure (MAP) was reduced by 50 mmHg. We studied the responses to hemorrhage under normal condition (Control) and after the pretreatment with 3 doses of L-NAME (1.6, 8, 40 mg/kg i.v. of NOX1.6, NOX8, and NOX40, respectively). Intravenous bolus injection of L-NAME produced a sustained increase in MAP and decrease in heart rate (HR). During hemorrhage, the MAP fell faster in the NOX8 and NOX40-treated groups than in Control group, but the control group showed same response to NOX1.6. HR greatly increased in NOX groups. The recovery from hemorrhagic hypotension was slowed in the control group, which was not treated with L-NAME. In comparison with the control group, NOX8 and NOX1.6-treated groups registered a significant recovery in MAP during the 15 min recovery period, but NOX40 brought about only a slight increase in MAP. NO precursor, L-arginine (150 mg/kg i.v.), produced significant bradycardia responses before and after hemorrhage and significant depressor response only after hemorrhagic hypotension regardless of pretreatment with L-NAME. These data suggest that the role of NO in blood pressure regulation is greater after hemorrhagic hypotension than basal condition, but the effect of NO can be detrimental to the recovery from hemorrhagic hypotension. In addition, the bradycardia response of L-arginine provides indirect evidence that NO may inhibit sympathetic activity, especially after hemorrhagic hypotension.

Effect of the inhibition of platelet activating factor on oxidative lung injury induced by interleukin-1 alpha

In order to know the pathogenesis of adult respiratory distress syndrome (ARDS) in association with the oxidative stress by neutrophils, the role of platelet activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine, PAF) was investigated during acute lung injury induced by interleukin-1alpha (IL-1) in rats. An insufflation of IL-1 into the rat's trachea increased the acetyltransferase activity in the lung and the increase of PAF content was followed. As evidences of acute lung injury by neutrophilic respiratory burst, lung leak index, myeloperoxidase activity, numbers of neutrophils in the bronchoalveolar lavage fluid, neutrophilic adhesions to endothelial cells and NBT positive neutrophils were increased after IL-1 treatment. In addition, a direct instillation of PAF into the trachea caused acute lung leak and the experimental results showed a similar pattern in comparison with IL-1 induced acute lung injury. For the confirmation of oxidative stress during acute lung leak by IL-1 and PAF, a histochemical electron microscopy was performed. In IL-1 and PAF treated lungs of rats, the deposits of cerrous perhydroxide were found. To elucidate the role of PAF, an intravenous injection of PAF receptor antagonist, WEB 2086 was given immediately after IL-1 or PAF treatment. WEB 2086 decreased the production of hydrogen peroxide and the acute lung leak. In ultrastructural study, WEB 2086 mitigated the pathological changes induced by IL-1 or PAF. The nuclear factor kappa B (NFkB) was activated by PAF and this activation was inhibited by WEB 2086 almost completely. Based on these experimental results, it is suggested that the PAF produced in response to IL-1 through the remodeling pathway has the major role for acute lung injury by neutrophilic respiratory burst. In an additional experiment, we can also come to conclude that the activation of the NFkB by PAF is thought to be the fundamental mechanism to initiate the oxidative stress by neutrophils causing release of proinflammatory cytokines and activation of phospholipase A2.

Effect of the inhibition of PLA 2 on oxidative lung injury induced by interleukin-1alpha

In order to understand the pathogenetic mechanism of adult respiratory distress syndrome (ARDS), the role of phospholipase A2 (PLA2) in association with oxidative stress was investigated in rats. Interleukin-1alpha (IL-1, 50 mug/rat) was used to induce acute lung injury by neutrophilic respiratory burst. Five hours after IL-1 insufflation into trachea, microvascular integrity was disrupted, and protein leakage into the alveolar lumen was followed. An infiltration of neutrophils was clearly observed after IL-1 treatment. It was the origin of the generation of oxygen radicals causing oxidative stress in the lung. IL-1 increased tumor necrosis factor (TNF) and cytokine-induced neutrophil chemoattractant (CINC) in the bronchoalveolar lavage fluid, but mepacrine, a PLA2 inhibitor, did not change the levels of these cytokines. Although IL-1 increased PLA2 activity time-dependently, mepacrine inhibited the activity almost completely. Activation of PLA2 elevated leukotriene C4 and B4 (LTC4 and LTB4), and 6-keto-prostaglandin F2alpha (6-keto-PGF2alpha) was consumed completely by respiratory burst induced by IL-1. Mepacrine did not alter these changes in the contents of lipid mediators. To estimate the functional changes of alveolar barrier during the oxidative stress, quantitative changes of pulmonary surfactant, activity of gamma glutamyltransferase (GGT), and ultrastructural changes were examined. IL-1 increased the level of phospholipid in the bronchoalveolar lavage (BAL) fluid, which seemed to be caused by abnormal, pathological release of lamellar bodies into the alveolar lumen. Mepacrine recovered the amount of surfactant up to control level. IL-1 decreased GGT activity, while mepacrine restored it. In ultrastructural study, when treated with IL-1, marked necroses of endothelial cells and type II pneumocytes were observed, while mepacrine inhibited these pathological changes. In histochemical electron microscopy, increased generation of oxidants was identified around neutrophils and in the cytoplasm of type II pneumocytes. Mepacrine reduced the generation of oxidants in the tissue produced by neutrophilic respiratory burst. In immunoelectron microscopic study, PLA2 was identified in the cytoplasm of the type II pneumocytes after IL-1 treatment, but mepacrine diminished PLA2 particles in the cytoplasm of the type II pneumocyte. Based on these experimental results, it is suggested that PLA2 plays a pivotal role in inducing acute lung injury mediated by IL-1 through the oxidative stress by neutrophils. By causing endothelial damage, functional changes of pulmonary surfactant and alveolar type I pneumocyte, oxidative stress disrupts microvascular integrity and alveolar barrier.

Effects of high dose of dexamethasone on PLA2, GGT activityand lung morphology in NNNMU-induced ARDS rats / 결핵

Background: In order to elucidate one of the pathogenic mechanisms of ARDS associated with pulmonary surfactant and oxidant injury, acute lung injury was induced by N-nitroso- N-methylurethane (NNNMU). In this model, the role of phospholipase A2 (PLA2), surfactant, gamma glutamyl transferase (GGT) and morphology were investigated to delineate one of the pathogenic mechanisms of ARDS by inhibition of PLA2 with high dose of dexamethasone. Method: Acute lung injury was induced in Sprague-Dawley rats by NNNMU which is known to induce acute lung injury in experimental animals. To know the function of the alveolar type II cells, GGT activity in the lung and bronchoalveolar lavage was measured. Surfactant phospholipid was measured also. PLA2 activity was measured to know the role of PLA2 in ARDS. Morphological study was performed to know the effect of PLA2 inhibition on the ultrastructure of the lung by high dose of dexamethasone. Results: Six days after NNNMU treatment (4 mg/kg), conspicuous pulmonary edema was induced and the secretion of pulmonary surfactant was decreased significantly. In the acutely injured rats' lung massive infiltration of leukocytes was observed. At the same time rats given NNNMU had increased PLA2 and GGT activity tremendously. Morphological study revealed bizarre shaped alveolar type II cells and hypertrophied lamellar bodies in the cytoplasm of the alveolar type II cells. But after dexamethasone treatment (20 mg/kg, for six days) in NNNMU-treated rats, these changes were diminished i.e. there were decrease of pulmonary edema and increase of surfactant secretion from alveolar type II cells. Rats given dexamethasone and NNNMU had decreased PLA2 and GGT activity in comparison to NNNMU induced ARDS rats. Conclusion: Inhibition of PLA2 by high dose of dexamethasone decreased pathological findings caused by infiltration of leukocytes and respiratory burst. Based on these experimental results, it is suggested that an activation of PLA2 is the one of the major factors to evoke the acute lung injury in NNNMU-induced ARDS rats.

Oxygen Consumption at Different Treadmill Speed and Grade in Athletes and Nonathletes

This study was aimed to elucidate the relationship between combinations of treadmill speed-grade and oxygen consumption(Vo2). Twenty athetic and 20 non-athletic male college students aged 19-24yr were employed to exercise on a treadmill using 4 speeds(4.02, 5.47, 6.76 and 8.05km/h) and 5 grades(0, 8, 12, 16 and 20%). A fixed speed was selected for each session with the grade increased every 3 min. The Vo2, heart rate, stride frequency and stride length were measured during the last min of each 3-min stage. Vo2increased linearly with increasing speed and grade showing significant multiple correlations in nonathletes(Vo2=3.64x+0.831y+0.031xy-7.03, R=0.98, P<0.01) and athletes(Vo2=3.48x+0.324y+0.112xy-5.74, R=0.99, P<0.01). Stride frequency and length tended to increase with increasing speed except for the transition from walking to runnig at 8.05Km/h at which the stride frequency ran up much higher with the stride length getting lower than at 6.76Km/h. Heart rate increased linearly with increasing Vo2. The rate of increase was higher during walking than during running. These results indicate that athletes have higher rate of increase in Vo2than nonathletes at near-maximal exercise and may be used as a guideline in predicting maximum oxygen comsumption and in prescribing exercise intensity.

Effects of intracerebroventricular angiotensin II on the response to hemorrhage in conscious normotensive and hypertensive rats / 대한내분비학회지

No abstract available.