Necrostatin-1 Synergizes the Pan Caspase Inhibitor to Attenuate Lung Injury Induced by Ischemia Reperfusion in Rats.

BACKGROUND: Both apoptosis and necroptosis have been recognized to be involved in ischemia reperfusion-induced lung injury. We aimed to compare the efficacies of therapies targeting necroptosis and apoptosis and to determine if there is a synergistic effect between the two therapies in reducing lung ischemia reperfusion injury. METHODS: Forty Sprague-Dawley rats were randomized into 5 groups: sham (SM) group, ischemia reperfusion (IR) group, necrostatin-1+ischemia reperfusion (NI) group, carbobenzoxy-Val-Ala-Asp-fluoromethylketone+ischemia reperfusion (ZI) group, and necrostatin-1+carbobenzoxy-Val-Ala-Asp-fluoromethylketone+ischemia reperfusion (NZ) group. The left lung hilum was exposed without being clamped in rats from the SM group, whereas the rats were subjected to lung ischemia reperfusion by clamping the left lung hilum for 1 hour, followed by reperfusion for 3 hours in the IR group. 1 mg/kg necrostatin-1 (Nec-1: a specific necroptosis inhibitor) and 3 mg/kg carbobenzoxy-Val-Ala-Asp-fluoromethylketone (z-VAD-fmk: a pan caspase inhibitor) were intraperitoneally administrated prior to ischemia in NI and ZI groups, respectively, and the rats received combined administration of Nec-1 and z-VAD-fmk in the NZ group. Upon reperfusion, expressions of receptor-interacting protein 1 (RIP1), receptor-interacting protein 3 (RIP3), and caspase-8 were measured, and the flow cytometry analysis was used to assess the cell death patterns in the lung tissue. Moreover, inflammatory marker levels in the bronchoalveolar lavage fluid and pulmonary edema were evaluated. RESULTS: Both Nec-1 and z-VAD-fmk, either alone or in combination, significantly reduced morphological damage, inflammatory markers, and edema in lung tissues following reperfusion, and cotreatment of z-VAD-fmk with Nec-1 produced the optimal effect. The rats treated with Nec-1 had lower levels of inflammatory markers in the bronchoalveolar lavage fluid than those receiving z-VAD-fmk alone (P < 0.05). Interestingly, the z-VAD-fmk administration upregulated RIP1 and RIP3 expressions in the lung tissue from the ZI group compared to those in the IR group (P < 0.05). Reperfusion significantly increased the percentages of necrotic and apoptotic cells in lung tissue single-cell suspension, which could be decreased by Nec-1 and z-VAD-fmk, respectively (P < 0.05). CONCLUSIONS: Nec-1 synergizes the pan caspase inhibitor to attenuate lung ischemia reperfusion injury in rats. Our data support the potential use of Nec-1 in lung transplantation-related disorders.

Methylene Blue Attenuates Lung Injury Induced by Hindlimb Ischemia Reperfusion in Rats.

OBJECTIVE: This study was aimed to investigate the protective effect of methylene blue against lung injury induced by reperfusion of ischemic hindlimb in a rat model. METHODS: Twenty-four healthy adult male Sprague-Dawley rats were equally randomized into three groups: sham (SM) group, ischemia reperfusion (IR) group, and methylene blue (MB) group. Rats in both IR and MB groups were subjected to 4 h of ischemia by clamping the left femoral artery and then followed by 4 h of reperfusion. Treatment with 1% methylene blue (50 mg/kg) was administrated intraperitoneally at 10 min prior to reperfusion in the MB group. After 4 h of reperfusion, malondialdehyde (MDA) level, myeloperoxidase (MPO), and superoxide dismutase (SOD) activities in lung tissue were detected; inflammatory cytokines, including IL-1ß and IL-6, were measured in bronchoalveolar lavage fluid (BALF); correspondingly, the morphological changes and water content in both gastrocnemius muscle and lung samples were evaluated. RESULTS: Hindlimb IR caused remarkable morphological abnormalities and edema in both muscle and lung tissues. SOD activity was decreased, both the MPO activity and MDA level in lung tissue, as well as IL-1ß and IL-6 levels in BALF, were increased in the IR group (p < 0.05). Compared with the IR group, SOD activity was increased, whereas MPO activity and MDA level in lung tissue and IL-1ß and IL-6 levels in BALF were decreased in the MB group (p < 0.05). Also, the histological damage and edema in both lung and muscle tissues were significantly attenuated by the treatment of methylene blue. CONCLUSION: Methylene blue attenuates lung injury induced by hindlimb IR in rats, at least in part, by inhibiting oxidative stress.

Colchicine protects rat skeletal muscle from ischemia/reperfusion injury by suppressing oxidative stress and inflammation.

OBJECTIVES: Neutrophils play an important role in ischemia/reperfusion (IR) induced skeletal muscle injury. Microtubules are required for neutrophil activation in response to various stimuli. This study aimed to investigate the effects of colchicine, a microtubule-disrupting agent, on skeletal muscle IR injury in a rat hindlimb ischemia model. MATERIALS AND METHODS: Twenty-one Sprague-Dawley rats were randomly allocated into three groups IR group, colchicine treated-IR (CO) group and sham operation (SM) group. Rats of both the IR and CO groups were subjected to 3 hr of ischemia by clamping the right femoral artery followed by 2 hr of reperfusion. Colchicine (1 mg/kg) was administrated intraperitoneally prior to hindlimb ischemia in the CO group. After 2 hr of reperfusion, we measured superoxide dismutase (SOD) and myeloperoxidase (MPO) activities, and malondialdehyde (MDA), tumor necrosis factor (TNF)-α and interleukin (IL)-1ß levels in the muscle samples. Plasma creatinine kinase (CK) and lactate dehydrogenase (LDH) levels were measured. We also evaluated the histological damage score and wet/dry weight (W/D) ratio. RESULTS: The histological damage score, W/D ratio, MPO activity, MDA, TNF-α and IL-1ß levels in muscle tissues were significantly increased, SOD activity was decreased, and plasma CK and LDH levels were remarkably elevated in both the IR and CO groups compared to the SM group (P<0.05). Colchicine treatment significantly reduced muscle damage and edema, oxidative stress and levels of the inflammatory parameters in the CO group compared to the IR group (P<0.05). CONCLUSION: Colchicine attenuates IR-induced skeletal muscle injury in rats.

COX-2 inhibition attenuates lung injury induced by skeletal muscle ischemia reperfusion in rats.

BACKGROUND: Skeletal muscle ischemia reperfusion accounts for high morbidity and mortality, and cyclooxygenase (COX)-2 is implicated in causing muscle damage. Downregulation of aquaporin-1 (AQP-1) transmembrane protein is implicated in skeletal muscle ischemia reperfusion induced remote lung injury. The expression of COX-2 in lung tissue and the effect of COX-2 inhibition on AQP-1 expression and lung injury during skeletal muscle ischemia reperfusion are not known. We investigated the role of COX-2 in lung injury induced by skeletal muscle ischemia reperfusion in rats and evaluated the effects of NS-398, a specific COX-2 inhibitor. METHODS: Twenty-four Sprague Dawley rats were randomized into 4 groups: sham group (SM group), sham+NS-398 group (SN group), ischemia reperfusion group (IR group) and ischemia reperfusion+NS-398 group (IN group). Rats in the IR and IN groups were subjected to 3h of bilateral ischemia followed by 6h of reperfusion in hindlimbs, and intravenous NS-398 8 mg/kg was administered in the IN group. In the SM and SN groups, rubber bands were in place without inflation. At the end of reperfusion, myeloperoxidase (MPO) activity, COX-2 and AQP-1 protein expression in lung tissue, PGE2 metabolite (PGEM), tumor necrosis factor (TNF)-α and interleukin (IL)-1ß levels in bronchoalveolar lavage (BAL) fluid were assessed. Histological changes in lung and muscle tissues and wet/dry (W/D) ratio were also evaluated. RESULTS: MPO activity, COX-2 expression, W/D ratio in lung tissue, and PGEM, TNF-α and IL-1ß levels in BAL fluid were significantly increased, while AQP-1 protein expression downregulated in the IR group as compared to that in the SM group (P<0.05). These changes were remarkably mitigated in the IN group (P<0.05). NS-398 treatment also alleviated histological signs of lung and skeletal muscle injury. CONCLUSION: COX-2 protein expression was upregulated in lung tissue in response to skeletal muscle ischemia reperfusion. COX-2 inhibition may modulate pulmonary AQP-1 expression and attenuate lung injury.

Fentanyl inhibits cell viability in human pancreatic cancer cell line and tumor growth in pancreatic cancer cell-transplanted mice.

Pancreatic cancer is a kind of devastating disease with a high mortality rate. Fentanyl has been widely applied to anesthesia and analgesia in pancreatic cancer therapy, and is also demonstrated to inhibit the growth of some kinds of cancer cells in existed studies. To investigate the functions of fentanyl in pancreatic cancer, we conducted a series of in vivo and in vitro experiments using human pancreatic cancer cells SW1990 and fentanyl treatment. The cells were transplanted to BALB/c nude mice to generate pancreatic tumor for monitoring tumor growth. Viability, apoptosis, migration and invasion, and cell cycle of SW1990 cells were also analyzed. To reveal the functional mechanisms of fentanyl, the expression changes of factors in these cellular activities were detected. Results showed a significant inhibition of pancreatic tumor growth in the fentanyl-treated group. Fentanyl also inhibited viability of SW1990 cells in vitro. Detailed results showed fentanyl led to promoted cell apoptosis via arresting cells in G0/G1 phase. It also suppressed cell migration and invasion. Further proofs indicated that the factors related to cell apoptosis (Bcl-2, p53 and Caspase-3), cell cycle (p21, Cyclin D1 and CDK4) and epithelial-mesenchymal transition (E-cadherin, Vimentin and α-SMA) showed the corresponding expression changes. Fentanyl might execute its functions via the suppressed MAPK pathways, since the key factors, p38, ERK1/2 and JNK were all down-regulated by fentanyl. This study indicated fentanyl could inhibit viability and growth of pancreatic cancer cells, providing a possible strategy for pancreatic cancer treatment.

Roxithromycin suppresses airway remodeling and modulates the expression of caveolin-1 and phospho-p42/p44MAPK in asthmatic rats.

Roxithromycin (RXM) expresses anti-asthmatic effects that are separate from its antibiotic activity, but its effects on airway remodeling are still unknown. Here, we evaluated the effects of RXM on airway remodeling and the expression of caveolin-1 and phospho-p42/p44mitogen-activated protein kinase (phospho-p42/p44MAPK) in chronic asthmatic rats. The chronic asthma was induced by ovalbumin/Al(OH)3 sensitization and ovalbumin challenge, RXM (30mg/kg) or dexamethasone (0.5mg/kg) was given before airway challenge initiation. We measured the thickness of bronchial wall and bronchial smooth muscle cell layer to indicate airway remodeling, and caveolin-1 and phospho-p42/p44MAPK expression in lung tissue and airway smooth muscle were detected by immunohistochemistry and western blot analysis, respectively. The results demonstrated that RXM treatment decreased the thickness of bronchial wall and bronchial smooth muscle cell layer, and also downregulated the phospho-p42/p44MAPK expression and upregulated the caveolin-1 expression. The above effects of RXM were similar to dexamethasone. Our results suggested that pretreatment with RXM could suppress airway remodeling and regulate the expression of caveolin-1 and phospho-p42/p44MAPK in chronic asthmatic rats.

Effects of COX-2 inhibitor on ventilator-induced lung injury in rats.

BACKGROUND: Mechanical ventilation especially with large tidal volume has been demonstrated to activate inflammatory response inducing lung injury, which could be attenuated by cyclooxygenase (COX)-2 inhibitors. As the main small integral membrane proteins that selectively conduct water molecules' transportation, aquaporin (AQP)-1 downregulation significantly related to lung edema and inflammation. This study aims to investigate the role of AQP1 in ventilator-induced lung injury in rats and evaluates the effects of COX-2 inhibition. METHODS: Forty rats were allocated into four groups, where rats in Groups LD (low volume+DMSO) and LN (low volume+NS-398) were given intravenously 2ml DMSO and 8mg/kg NS-398 (a specific COX-2 inhibitor, dissolved in 2ml DMSO) before 4-hour lower tidal volume ventilation (8ml/kg), respectively, while DMSO and NS-398 were administrated in the same manner before 4-hour injurious ventilation (40ml/kg) in Groups HD (high volume+DMSO) and HN (high volume+NS-398). The arachidonic acid metabolites (6-keto prostaglandin F1α, thromboxane B2), inflammatory cytokines (tumor necrosis factor-α, interleukin-1ß, 6, 8) and total protein levels in bronchoalveolar lavage (BAL) fluid and COX-2 mRNA and AQP1 protein expression in lung tissue were detected; water content and lung morphology were also evaluated. RESULTS: Compared to Groups LD and LN, the rats in Groups HD and HN suffered obvious lung morphological changes with higher wet-to-dry weight ratio and lung injury score, and the levels of arachidonic acid metabolites, inflammatory cytokines and total protein in BAL fluid were increased, the expression of COX-2 mRNA was significantly upregulated and AQP1 protein was downregulated in lung tissue (p<0.05). The changes in BAL fluid and the severity of lung injury were attenuated, and AQP1 expression was upregulated in Group HN as compared to HD (p<0.05). CONCLUSIONS: Ventilation with large tidal volume causes inflammatory mediator production and AQP1 downregulation, which could be attenuated by COX-2 inhibition.

Sevoflurane attenuates pulmonary inflammation and ventilator-induced lung injury by upregulation of HO-1 mRNA expression in mice.

BACKGROUND: Mechanical ventilation has been documented to paradoxically cause lung injury. As a commonly used volatile anesthetic, sevoflurane has been proven to possess antiinflammatory and antioxidative properties. This study aims to investigate the protective effects of sevoflurane on inflammation and ventilator-induced lung injury during mechanical ventilation in healthy mice. METHODS: The adult healthy mice were divided into four groups, each consisting of ten subjects: mice in group Con-L(VT) and group Sev-L(VT) were ventilated with tidal volumes of 8 mL/kg for 4 hours, while those in group Con-H(VT) and group Sev-H(VT) were ventilated with tidal volumes of 16 mL/kg instead. Control mice (group Con-L(VT) and Con-H(VT)) were subjected to fresh air, while sevoflurane-treated mice (groups Sev- L(VT) and Sev-H(VT)) were subjected to air mixed with 1 vol% sevoflurane. After 4 hours of ventilation, the bronchoalveolar lavage (BAL) fluid was collected and analyzed for the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-6, and IL-10. Lung homogenates were harvested to detect the expression of nuclear factor-kappa B (NF-κB) and heme oxygenase (HO)-1 mRNA by reverse transcription-polymerase chain reaction method. Lung damage was evaluated using the modified Ventilator-Induced Lung Injury histological scoring system. RESULTS: Compared to group Con-L(VT), the levels of TNF-α, IL-1ß, IL-6, and IL-10 in BAL fluid, mRNA expressions of NF-κB and HO-1 in lung tissue, and lung injury scores were significantly increased in group Con-H(VT); compared to group Con-H(VT), group Sev-H(VT) BAL samples showed decreased levels of TNF-α, IL-1ß, and IL-6; they also showed increased levels of IL-10, the downregulation of NF-κB mRNA, and HO-1 mRNA upregulation; the lung injury scores were significantly lower in group Sev-H(VT) than group Con-H(VT). CONCLUSION: Mechanical ventilation with high tidal volume might lead to lung injury, which could be significantly, but not completely, attenuated by sevoflurane inhalation by inhibiting the NF-κB-mediated proinflammatory cytokine generation and upregulating HO-1 expression.

Diabetes increases inflammation and lung injury associated with protective ventilation strategy in mice.

BACKGROUND: Mechanical ventilation may paradoxically cause lung injury. Protective mechanical ventilation strategy utilizing low tidal volume and high frequency has been shown to attenuate inflammation and reduce mortality in non-diabetic patients. The purpose of this present study was to observe the effects of diabetes on inflammation and lung injury in mice with protective ventilation strategy. METHODS: Forty mice were included in our study. The mice in Group Dia-MV and Con-MV were subjected to 4 hour-ventilation. And the mice in Group Dia-SB and Con-SB were exposed to room air breathing spontaneously for 4h. Tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-10 (IL-10), superoxide dismutase (SOD) and malondialdehyde (MDA) levels in serum were detected and the expression of inflammatory cytokine mRNA was also determined in lung tissue. Lung damage was assessed using a modified lung injury score. RESULTS: The serum levels of TNF-α, IL-6, and IL-10 in Group Dia-MV were significantly higher than those in Group Dia-SB or Group Con-MV or Group Con-SB (P<0.05). Quantitative RT-PCR analysis of pro-inflammatory cytokines in lung homogenates presented similar results. The mice in Group Dia-MV suffered obvious lung histological changes, whose lung injury scores were significantly higher in Group Dia-SB as compared to Group Con-SB , Group Con-MV or Group Dia-SB (P<0.05). CONCLUSIONS: Diabetes increased the inflammation reaction and associated lung injury in mice in spite of the protective mechanical ventilation strategy based on low tidal volumes and high frequency.

[Role of vascular endothelial active facters in gas exchange impairment induced by tourniquet and the effect of shenmai injection].

OBJECTIVE: To investigate the effect of Shenmai injection on vascular endothelial active facters nitric oxide (NO) and endothelin-1 (ET-1), and pulmonary gas exchange induced by tourniquet deflation in patients undergoing lower extremity surgery. METHOD: Twenty-six patients scheduled for unilateral lower extremity surgery were randomly divided into 2 groups: control group (group C, n = 14) and Shenmai injection group (group SM, n = 12). All the patients agreed to a combined spinal-epidural anesthesia at the L2-L3 interspace and a radial artery catheter was placed for sampling. Patients in group SM were injected Shenmai injection 0.6 mL x kg(-1) and physiological saline 100 mL, while patients in group C were injected equal volume of normal saline instead 15 min before tourniquet inflation. Blood samples which were used for blood gas analysis and measurement of nitric oxide (NO) and endothelin-1 (ET-1) were taken before tourniquet inflation (T0, baseline) and 30 min (T1), 2 h (T2), 6 h (T3), 24 h (T4) after tourniquet deflation. RESULT: Compared with the baseline values at T0, in group C at T3 P(a) O2 and the levels of NO were significantly decreased, while P(A-a) DO2 and the levels of ET-1 at T3 were significantly increased (P < 0.05 or P < 0.01), in group SM, the levels of NO at T3 were significantly decreased (P < 0.05). Compared with group C, the changes of P(a)O2, P(A-a) DO2, NO and ET-1 were significantly mitigated in group SM. CONCLUSION: The concentrations of NO and ET-1 is connected with the pulmonary gas exchange impairment induced by tourniquet application. Shenmai injection can improve the pulmonary gas exchange based on rising the level of NO, reducing the level of ET-1.

Effects of shenmai injection on pulmonary aquaporin 1 in rats following traumatic brain injury.

BACKGROUND: Aquaporin-1 (AQP1) has involved in fluid transport in diverse pulmonary edema diseases. Our study aimed to explore the dynamic changes of AQP1 in pulmonary water metabolism in rats following traumatic brain injury (TBI) and the protective effect provided by shenmai injection. METHODS: Sixty male Sprague Dawley rats weighting 280 - 300 g were randomly divided into three groups: the normal control group, the model group and the shenmai injection (SMI) group. One piece skull was taken away without injuring cerebral tissue in normal control group, while rats in model group and SMI group were subject to free fall injury in the cerebral hemisphere. Rats in model group received intraperitoneal normal sodium (15 ml/kg) at one hour post-injury and the same dose of shenmai injection instead in SMI group, respectively. The expression of AQP1 was detected by immunohistochemical analysis and semi-quantitative RT-PCR at 0 hour, 10 hours, 72 hours and 120 hours after TBI. Arterial blood gas analysis and lung wet to dry were also measured. RESULTS: AQP1 was mainly presented in the capillary endothelium and slightly alveolar epithelial cells in three groups, but the expression of AQP1 in the normal control group was positive and tenuous, weakly positive in the model and SMI groups, respectively. Compared with normal control group, AQP1 mRNA levels were down regulated in the model and SMI groups at 10 hours, 72 hours and 120 hours (P < 0.05). While AQP1 mRNA levels in the SMI group was up-regulated than that in the model group (P < 0.05). Lung wet to dry weight ratio (W/D) in the model and SMI groups at 10 hours were higher than that in normal control group (P < 0.05). Compared with normal control group, PaO2 was markedly lower in the model and SMI groups (P < 0.05), but there were no statistically significant differences between model and SMI groups (P > 0.05). CONCLUSIONS: The decreased AQP1 expression may be involved in the increased lung water content and dysfunction of pulmonary water metabolism following TBI. The treatment with SMI could improve water metabolism by promoting AQP1 expression.

Effect of Shenmai injection, a traditional Chinese medicine, on pulmonary dysfunction after tourniquet-induced limb ischemia-reperfusion.

BACKGROUND: Tourniquet has been considered as a recognized cause of lower limb ischemia-reperfusion injury in the orthopedic field. This study investigates pulmonary function after tourniquet deflation and the protective effect of Shenmai injection (SMI), a traditional Chinese medicine. METHODS: Twenty-eight patients undergoing lower extremity surgery were randomized into a control group (group C) and a SMI group (group S), 14 patients in each group. Blood gas and circulating indicators (malondialdehyde, interleukin [IL]-6, and IL-8) were measured immediately before tourniquet inflation and at 0.5 hour, 2 hours, 6 hours, and 24 hours after tourniquet deflation. RESULTS: Plasma levels of malondialdehyde, IL-6, and IL-8 in group C were significantly increased over baselines from 2 hours to 24 hours after tourniquet deflation and the levels reached their peaks at 6 hours after tourniquet deflation, when arterial partial pressures of oxygen and arterial-alveolar oxygen tension ratio were decreased, whereas alveolar-arterial oxygen difference was increased significantly. Both the changes in blood gas variables and plasma mediators were attenuated in group S. CONCLUSION: Pulmonary gas exchange is impaired after lower limb ischemia-reperfusion induced by clinical tourniquet application. Pretreatment with SMI, a traditional Chinese medicine, attenuates lipid peroxidation and systemic inflammatory response and mitigates pulmonary dysfunction.

Pulmonary gas exchange impairment following tourniquet deflation: a prospective, single-blind clinical trial.

The tourniquet has been considered as a recognized cause of limb ischemia/reperfusion injury in orthopedic surgery resulting in a transient neutrophil, monocyte activation, and enhanced neutrophil transendothelial migration with potential remote tissue injury. This study investigated the effect of unilateral tourniquet application within a safe time limit on pulmonary function and the roles of lipid peroxidation and systemic inflammatory response. Thirty patients undergoing unilateral lower extremity surgery with or without tourniquet were equally divided into a control group with no tourniquet (Group C) and a tourniquet (Group T). Arterial partial pressure of oxygen (P(a)O(2)), arterial-alveolar oxygen tension ratio (a/A ratio), alveolar-arterial oxygen difference (A-aDO(2)) and respiratory index, plasma malondialdehyde, serum interleukin (IL) -6 and IL-8 levels were measured immediately before and 1 hour after tourniquet inflation/operation beginning, 0.5, 2, 6, and 24 hours after tourniquet deflation/operation ending. The results represented no significant changes in Group C with regard to either blood gas variables or levels of circulating mediators, while blood gas variable changes of greater A-aDO(2) and respiratory index and lower PaO2 and a/A ratio were shown at 6 hours following tourniquet deflation. The levels of malondialdehyde, IL-6, and IL-8 were increased over baseline values from 2 to 24 hours following tourniquet deflation in Group T. We concluded that tourniquet application within a safe time limit may cause pulmonary gas exchange impairment several hours after tourniquet deflation, where lipid peroxidation and systemic inflammatory response may be involved.

Ischemic preconditioning attenuates pulmonary dysfunction after unilateral thigh tourniquet-induced ischemia-reperfusion.

BACKGROUND: Acute lung injury is a recognized complication of lower limb ischemia-reperfusion that has been demonstrated experimentally and in the clinical setting of aortic surgery. The application of a tourniquet can cause lower limb ischemia-reperfusion in orthopedic surgery. We studied the effect of unilateral thigh tourniquet-induced lower limb ischemia-reperfusion on pulmonary function, and the role of ischemic preconditioning in attenuating pulmonary dysfunction. METHODS: Thirty ASA I or II patients scheduled for lower extremity surgery were randomized into 2 groups: a limb ischemia-reperfusion group with tourniquet application (ischemia-reperfusion group, n = 15) and an ischemia preconditioning group (preconditioning group, n = 15), in which patients received 3 cycles of 5 minutes of ischemia, alternating with 5 minutes of reperfusion before extended use of the tourniquet. Blood gas, plasma malondialdehyde, and serum interleukin-6 (IL-6), IL-8, and IL-10 levels were measured just before tourniquet inflation, 1 hour after inflation and 2 hours, 6 hours, and 24 hours after tourniquet deflation. Arterial-alveolar oxygen tension ratio, alveolar-arterial oxygen tension difference, and respiratory index also were calculated. RESULTS: In comparison with the baseline values, arterial Po(2) and arterial-alveolar oxygen tension ratio were decreased, while alveolar-arterial oxygen tension difference and respiratory index were increased significantly 6 hours after tourniquet deflation in both groups (P < 0.01). However, these changes were less significant in the ischemic preconditioning group than those in the lower limb ischemia-reperfusion group (P < 0.01). Similarly, the increases in the malondialdehyde, IL-6, and IL-8 from 2 hours to 24 hours after release of the tourniquet in the lower limb ischemia-reperfusion group were attenuated by ischemic preconditioning. CONCLUSIONS: Pulmonary gas exchange is impaired after lower limb ischemia-reperfusion associated with the clinical use of a tourniquet for lower limb surgery. Ischemic preconditioning preceding tourniquet-induced ischemia attenuates lipid peroxidation and systemic inflammatory response and mitigates pulmonary dysfunction.