To determine the therapeutic effect of fasciotomy+hypertonic saline flushing for crush syndrome (CS) in rats.

SD rats (weighing 250±20 g) were randomly divided into normal control group (NC group, n=10) and CS group (n=14).Rat CS model was established by compressing the buttocks and both hindlimbs with a weight of 7.5 kg for 4 h, and the presence of hematuria or anuria was defined as success of modeling.In 6 h after modeling, the fluid exuded from the compressed tissues was collected, and the contents of potassium ions (K⁺), calcium ions (Ca²⁺), myoglobin (Mb), and lactic acid (Lac) in the exudate of each group were detected.Another 63 male SD rats (weighing 250±20 g) were randomly and equally divided into blank control group (NC group), CS group, CS+fasciotomy group (CSO group), and CS+fasciotomy+difference doses of NaCl solution irrigation groups (0.9%, 3.0%, 5.0% and 7.0% NaCl, respectively).At 6 h after modeling, the renal blood flow was measured, the contents of K⁺, Ca²⁺, Mb, Lac, AST, ALT, Cr, and urea in the plasma of each group were detected, and the compressed tissues and kidney tissues were observed for pathological changes.

Detection of exudates showed the contents of K⁺, Mb, and Lac were significantly higher, while that of Ca²⁺ content was obviously decreased in the CS group than the NC group (P < 0.01).Plasma detection indicated that simple fasciotomy had no therapeutic effect, while it combined with NaCl solution flushing decreased the contents of K⁺, Mb, Lac, AST, ALT, urea and Cr, and increased the Ca²⁺ content in the blood of the CS group (P < 0.05).Laser speckle contrast imaging revealed that simple fasciotomy could not increase renal blood flow, while the combination of fasciotomy and NaCl solution flushing notably increased the renal blood flow in the CS rats (P < 0.05).In addition, the combination treatment reduced the pathological damage in the kidneys induced by CS, but fasciotomy alone had no such effect (P < 0.5).

Fasciotomy combined with hypertonic NaCl solution (3%) flushing can significantly reduce the damage caused by CS in rats.

To explore the protective effect of L-carnitine on myocardial systolic dysfunction in sepsis and its underlying mechanism.

A mouse sepsis model was established by cecal ligation and puncture (CLP). Ten-week-old male SPF-grade C57 BL/6 mice (body weight 20~30 g) were randomly divided into 5 groups via random number table: Sham group, Sepsis group, L-carnitine group, L-carnitine+Etomoxir (Eto) group, and Eto group. Echocardiography assessed cardiac function, ELISA measured serum creatine kinase isoenzyme MB (CK-MB) levels, and 72-hour survival rates were recorded to evaluate L-carnitine’s effects on cardiac function. Cardiomyocytes were isolated, and a cell microtensiometer was used to detect cardiomyocyte contractile function and calcium transients. Myocardial tissues were collected from each group, and ELISA was used to determine the contents of triglyceride (TG), free fatty acid (FFA), and adenosine triphosphate (ATP). An in vitro sepsis model was constructed by stimulating HL-1 cardiomyocytes with lipopolysaccharide (LPS) for 12 hours, which was divided into 5 groups: control (CTRL) group, LPS group, L-carnitine group, L-carnitine + Eto group, and Eto group. ELISA was used to detect the contents of TG, FFA, and ATP as well as the activity of carnitine palmitoyltransferase 1A (CPT1A) in cardiomyocytes. A cellular energy metabolism analysis system was employed to measure fatty acid oxidation capacity, and Western blot was used to detect the protein expression of CPT1A in cardiomyocytes. BODIPY-FL-C16 (green fluorescently labeled palmitic acid) was utilized to detect the distribution of fatty acids in the cytoplasm and mitochondria via immunofluorescence technology, thereby observing the ability of cells to transport fatty acids into mitochondria.

Compared with the Sham group, cardiac function was significantly impaired in the Sepsis group, as evidenced by decreased ejection fraction and mean arterial pressure (P<0.05), along with elevated levels of the cardiac injury marker CK-MB (P<0.05). Treatment with L-carnitine significantly improved myocardial function, restored blood pressure in septic mice, and increased their survival rate from 12.50% to 81.25%(P<0.05). Compared with the Sham group, the contractile function and calcium transients of acutely isolated single cardiomyocytes were significantly reduced in the Sepsis group (P<0.05), while L-carnitine treatment remarkably restored the contractile function and calcium release capacity of septic cardiomyocytes (P<0.05). Both in vivo and in vitro experiments showed that TG and FFA levels were significantly increased (P<0.05), and ATP levels was significantly decreased (P<0.05) in the Sepsis and LPS groups—effects significantly reversed by L-carnitine treatment. Compared with the CTRL group, the basal oxidation rate and maximum oxidation capacity of fatty acids in cardiomyocytes of the LPS group were significantly reduced (P<0.05), and L-carnitine treatment notably improved these indicators.Compared with the CTRL group, the expression and activity of CPT1A in cardiomyocytes of the LPS group were significantly decreased (P<0.05), while L-carnitine treatment significantly increased the expression and activity of CPT1A (P<0.05). In LPS group cardiomyocytes, green fluorescently labeled palmitic acid primarily formed numerous granular/clumpy aggregates in the cytoplasm with minimal mitochondrial colocalization. In the L-carnitine group, the green fluorescent granules in the cytoplasm of cardiomyocytes were smaller, and colocalization with mitochondria was increased. However, the L-carnitine + Eto group exhibited similar phenomena to the LPS group. In addition, both in vivo and in vitro experiments demonstrated that treatment with the CPT1A inhibitor Eto reversed the effect of L-carnitine. Compared with the L-carnitine group, the ATP content in the L-carnitine + Eto group was significantly decreased (P<0.05), while the FFA content was significantly increased (P<0.05).

L-carnitine facilitates fatty acid entry into mitochondria for β-oxidation via a CPT1A-dependent mechanism, thereby ameliorating fatty acid oxidation dysfunction in septic cardiomyocytes and improving myocardial contractile function.

To investigate the role of pericyte ferroptosis in the injury of pulmonary vascular barrier in septic rats and identify the protective effect of ferrostatin-1 (Fer-1), a ferroptosis inhibitor, on pulmonary vascular barrier function.

①Animal experiment: The septic model of rats was established by cecal ligation and puncture (CLP), and 156 SD rats were randomly divided into sham group, CLP group and Fer-1 group (10 mg/kg Fer-1 intraperitoneally in 1 h before CLP). Single cell suspension of rat lung from the sham-operation group was obtained by flow cytometry as an unstained blank control. The abundance of pericytes in pulmonary venules, changes in pulmonary vascular permeability, lung wet to dry weight ratio and lung histopathology of rats in each group were observed. Meanwhile, the contents of lipid peroxidation (LPO) in pulmonary pericytes and venules, as well as the expression of ferroptosis marker proteins including glutathione peroxidase 4 (GPX4) and cyclooxygenase-2 (COX2) were also measured in each group. ②Cell experiment: Primary pericytes were isolated and divided into normal control group, lipopolysaccharide (LPS) group (treated with 10 μg/mL LPS for 12 h), and Fer-1 group (pretreated with 2 μmol/L Fer-1 for 12 h before LPS stimulation). The contents of ROS, Lipid ROS and Fe²⁺ and the expression levels of GPX4 and COX2 in the pericytes of each group were investigated.

In vivo, massive detachment of pericytes from pulmonary veins, serious leakage of pulmonary vessels, large quantities of Evans blue extravasation, severe damage of lung pathological structure were observed in the CLP group, accompanied with infiltration of massive inflammatory cells, increase in lung wet-dry weight ratio, and accumulation of LPO in pulmonary vascular pericytes, which indicated severe ferroptosis. However, Fer-1 pretreatment reduced the ferroptosis of pulmonary pericytes, decreased the loss of pericytes, alleviated pulmonary vascular leakage, improved lung structure, and greatly lowered the contents of LPO in the pericytes (P<0.01). In vitro, LPS significantly impaired pericytes viability and induced accumulations of ROS, Lipid ROS and Fe²⁺ in the pericytes. Meanwhile, LPS down-regulated the expression of GPX4 while up-regulated that of COX2. Administration of Fer-1 restored the pericytes viability and the expression of GPX4, and decreased the levels of intracellular ROS, Lipid ROS, Fe²⁺ and COX2 expression.

Sepsis may induce the ferroptosis and detachment of pulmonary pericytes, and then impair pulmonary vascular barrier function. The ferroptosis inhibitor Fer-1 can antagonize pulmonary pericytes ferroptosis and play a vital role in protecting pulmonary vascular barrier function.

To investigate the protective effects of parthenolide (PTL) on intestinal barrier function in septic rats.

The septic model of rats was established by cecal ligation and puncture (CLP), and SD rats (200±20 g, male/female) were randomly divided into 6 groups: normal control (NC) group, sepsis (Sep) group, conventional treatment (LR) group (lactated Ringer's solution resuscitation+dopamine+cefuroxime sodium), and parthenolide (PTL) groups (1, 5 and 10 mg/kg parthenolide respectively on the basis of LR group). The changes of arterial blood pressure, survival rate and survival time of rats in each group were observed, and the optimal concentration of parthenolide in the treatment was determined. Moreover, the effects of parthenolide (at the optimal concentration) on the intestinal permeability, intestinal pathology, inflammatory cytokine levels, as well as liver and kidney functions in septic rats were further investigated.

As compared with the NC group, the survival rate and survival time of septic rats were significantly decreased, so was the mean arterial pressure (MAP), while the levels of blood inflammatory cytokines were increased, and the liver and kidney functions were damaged. Conventional treatment improved the survival rate and survival time of septic rats to a certain extent, reduced the levels of inflammation cytokines and alleviated the liver and kidney damages. When compared with the LR group, the survival rates of 1, 5, and 10 mg/kg PTL groups were increased by 6.3%, 43.8%, and 18.8%, respectively, and the MAP in the PTL groups was elevated by 1.4%, 12.8%, and 7.1%, respectively, with those of 5 mg/kg PTL more significant. Further research found that PTL remarkably ameliorated the intestinal barrier function in septic rats, shown as a 55.1% reduction in the content of intestinal Evans blue (EB), a 69.5% decline in blood D-lactic acid concentration as compared with the LR group (P<0.05), along with an improvement in intestinal epithelial structure, and a decrease in epithelial cell necrosis. In addition, PTL reduced the inflammatory cytokine levels greatly and improved the liver and kidney functions in septic rats.

PTL shows obvious protective effects on the intestinal barrier function of septic rats, and its mechanism may be related to the inhibition of septic inflammatory response.