Alteration in intestinal epithelial permeability and its role in the pathogenesis of burn shock / 中华烧伤杂志

The intestinal epithelial barrier serves a dual role: to keep harmful external agents out of the body and to allow beneficial nutrients to enter the body. Tight junction (TJ) is of crucial importance for the barrier function. Over the past 15 years, some of the molecular events underlying the epithelial barrier regulation have been described. This forum introduces briefly the molecular structure of TJ and its regulation in gut barrier. It was shown that gut barrier function was impaired as early as 5 minutes post burn and became worst by 4 hours. In this forum the mechanism of gut barrier injury in burns is described, and it includes 4 aspects: the phosphorylation of TJ protein and perijunctional actin-myosin ring, the reduction of TJ proteins expression, the endocytosis of TJ proteins, and the apoptosis and necrosis of the epithelial cells. It is well known that the increase in gut permeability promotes bacterial translocation in burns. Moreover, a new auto-digestion theory of gut in shock and MODS was recently raised. Therefore, protection against gut barrier damage has again been recognized as a therapeutic target in shock and MODS treatment.

Effect of Bay K 8644 on arteriole smooth muscle cell membrane potential in rats with severe hemorrhagic shock / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of Ca(2+) influx through L-type Ca(2+) channels on normal and hyperpolarized membrane potential of arteriole smooth muscle cells (ASMCs) in rats.</p><p><b>METHODS</b>The ASMCs isolated from normal rats and those with severe hemorrhagic shock were labeled with DiBAC4 (3) for membrane potential detection.</p><p><b>RESULTS</b>Ca(2+) influx caused hyperpolarization of the membrane potential in the normal ASMCs but depolarization in the cells from rats with hemorrhagic shock, and this effect could be inhibited by TEA.</p><p><b>CONCLUSION</b>Ca(2+)-activated potassium channels activated by Ca(2+) influx through L-type Ca(2+) channels in normal ASMCs to cause hyperpolarization but leads directly to membrane potential depolarization in ASMCs from rats with severe hemorrhagic shock. This finding can be meaningful for treatment of vascular hyporeactivity in advanced stage of severe shock.</p>

Role of Rho kinase in reorganization of the vascular endothelial cytoskeleton induced by rat burn serum / 中华烧伤杂志

<p><b>OBJECTIVE</b>To investigate the changes in endothelial cytoskeletal reorganization and the role of Rho in the signal transduction pathway.</p><p><b>METHODS</b>ECV304 cells were cultured and randomly divided into following groups: i.e. sham (with normal rat serum treatment), burn (with burn rat serum treatment), Y (with 30 micromol/L Rho kinase inhibitor Y-27632 treatment), burn plus Y (pretreatment of cells with burn serum before treated with 30 micromol/L Y-27632), Y plus burn (pretreatment of cells with Y-27632 for 1 hour before treated with burn serum), LPA (with normal rat serum and 13 micromol/L LPA), and LPA plus Y (pretreatment of cells with LPA before treated with Y-27632) groups. The indices were examined at 6, 7 and 8 posttreatment hours (PTH) in all groups except in Y group. The endothelial morphology was observed with HE staining. Endothelial cytoskeleton was observed by dual-fluorescence labeling of filamenta (F) with Rhodamine-phalloidin and monomer (G) with oregon green labeled DNAase. The actin content in the cells in all groups was measured with flow cytometry.</p><p><b>RESULTS</b>In sham and control group, the cells were in fusiform or polygonal shape, with satisfactory growth; filamentous actin (F-actin) was mainly distributed in the peripheral site of the cytoplasm and formed peripheral filamental band. The cells became confluent to form a single layer with reticular structure. Globular actin (G-actin) was concentrated in the nucleus and per nucleus. In burn group, after 6 hours of burn serum treatment, the ability of cells to adhere to vessel wall was weakened, and a striking reorganization of the actin cytoskeleton and the formation of the stress fibers were found. Furthermore, the fluorescent intensity of the peripheral filament bands was weakened, and dispersed actin monomers were seen in the cytoplasm. This reaction was enhanced along with elapse of stimulation time. In burn plus Y or Y plus burn group, the cells grew and adhered well to the wall of culture vessel. The distribution of the filamentous actin was the same as the sham group, while the stress fiber decreased in amount obviously. The structure of globular actin was condensed with little G-actin in the cytoplasm. The changes in actin cytoskeleton in LPA group was similar to that in burn group. The effects of LPA on actin reorganization could also be reversed by Y-27632. The content of F-actin in burn group at 6 PTH (0.63 +/- 0.07) was lower than that in sham group (0.75 +/- 0.08), while the content of G-actin in burn group (1.28 +/- 0.27) was higher than that in sham group (1.16 +/- 0.16, P > 0.05).</p><p><b>CONCLUSION</b>Burn serum induces vascular endothelial actin cytoskeleton reorganization in endothelial cells via the Rho-dependent signal pathway. Similar to the effect of LPA, this effect could be reversed by Y-27632.</p>

Effects of lipopolysaccharide on actin reorganization and actin pools in endothelial cells / 中华创伤杂志(英文版)

<p><b>OBJECTIVE</b>To investigate the dose and time-dependent effects of lipopolysaccharide (LPS) on cytoskeletal F-acitn and G-actin reorganizations by visualizing their distribution and measuring their contents in human umbilical vein endothelial cell line ECV-304.</p><p><b>METHODS</b>F-actin was labeled with rhodamine-phalloidin and G-actin with deoxyribonuclease I (DNase I)conjugated with fluorescein isothiocyanate (FITC). Contents of cytoskeletal proteins were obtained by flow cytometry.</p><p><b>RESULTS</b>F-actin was mainly distributed peripherally in endothelial cells under normal conditions. LPS stimulation caused the formation of stress fibers and filopodia. G-actin was normally seen in perinuclear and nuclear areas in control ECV-304 cells. Under LPS stimulation, G-actin dots appeared in the cytoplasmic region. The actin disorganization was accompanied by the time- and dose- dependent decrease in F-actin pool and increase in G-actin pool.</p><p><b>CONCLUSIONS</b>LPS can induce characteristic morphological alterations of actin cytoskeleton and formation of intercellular gap in endothelial cells, accompanied by changes in F-actin and G-actin pools.</p>

Expression of intercellular adhesion molecule-1 in different organs of the mice with endotoxic shock induced by lipopolysaccharide / 生理学报

To investigate and compare the expression of intercellular adhesion molecule-1 (ICAM-1) in different organs of the mice with endotoxic shock induced by lipopolysaccharide (LPS), protein and mRNA of ICAM-1 were measured by Western blotting and RT-PCR respectively in different organs of BALB/c mice administered intraperitoneally with 5 mg/kg LPS. The results showed that the constitutive expression of ICAM-1 protein and mRNA was the greatest in the lungs, followed by the spleen, kidney and intestine. After LPS stimulation, the upregulation of ICAM-1 was still greatest in the lungs, followed by the liver, spleen, heart, kidney and intestine. Compared with the normal mice, the expression of ICAM-1 protein in endotoxic shocked mice increased by 4.5-fold in the lungs, 3.0-fold in the kidney, 1.5-fold in the spleen; the expression in the liver and heart was negative under normal condition and changed into positive during endotoxic shock; but ICAM-1 expression in the intestine did not change significantly. The expression of ICAM-1 mRNA also increased consistently. These data highlight that LPS can up-regulate ICAM-1 protein and mRNA expression in different tissues of the mice with endotoxic shock. The difference in ICAM-1 expression among the organs may lead to different sensitivity of organ damage in endotoxic shock. This suggests that inhibition of ICAM-1 expression may be a useful principle for prevention and treatment of endotoxic shock.