Effects of Seawater Immersion on Lethal Triad and Organ Function in Healthy and Hemorrhagic Shock Rats.

INTRODUCTION: Marine casualties are increasing, and mortality from trauma associated with immersion in seawater is high. However, the associated pathophysiological characteristics remain unclear, limiting research into the early emergency treatment strategy. METHODS: Healthy and 50% hemorrhagic shock rats were soaked in 15°C and 21°C seawater for 2 h, 4 h and 6 h, respectively, and the effects on vital signs, internal environment, tissue metabolism, lethal triad, vital organ functions and survival were observed. RESULTS: Immersion in seawater can cause death in healthy rats. Rats with hemorrhagic shock in 15°C seawater showed a lower survival rate than the corresponding groups in 21°C seawater. Moreover, compared with 21°C seawater, 15°C seawater played a more remarkable role in decreasing mean arterial pressure, heart rate, and respiration rate, increasing water content and decreasing Na+/K+-ATPase activity in the brain and lung; increase in plasma osmolality, Na+, K+, Cl-, and the occurrence of the lethal triad manifested by a decrease in core body temperature, pH, lactate, and an increase in coagulation parameters, as well as damage to cardiac, intestinal, hepatic, and renal functions in rats with hemorrhagic shock. CONCLUSIONS: Immersion in seawater at low temperatures could be lethal to healthy rats, causing the occurrence of a lethal triad and damage to vital organs. Furthermore, 15°C-seawater had a more significant effect than 21°C-seawater on aggravating the imbalance of internal environment and tissue metabolism, resulting in a higher incidence of the lethal triad and thus aggravating the dysfunctions of vital organs, which eventually resulted in higher mortality in rats with hemorrhagic shock.

Effects of Malate Ringer's solution on myocardial injury in sepsis and enforcement effects of TPP@PAMAM-MR.

BACKGROUND: Myocardial dysfunction played a vital role in organ damage after sepsis. Fluid resuscitation was the essential treatment in which Lactate Ringer's solution (LR) was commonly used. Since LR easily led to hyperlactatemia, its resuscitation effect was limited. Malate Ringer's solution (MR) was a new resuscitation crystal liquid. Whether MR had a protective effect on myocardial injury in sepsis and the relevant mechanism need to be studied. METHODS: The cecal ligation and puncture (CLP) inducing septic model and lipopolysaccharide (LPS) stimulating cardiomyocytes were used, and the cardiac function, the morphology and function of mitochondria were observed. The protective mechanism of MR on myocardial injury was explored by proteomics. Then the effects of TPP@PAMAM-MR, which consisted of the mitochondria- targeting polymer embodied malic acid, was further observed. RESULTS: Compared with LR, MR resuscitation significantly prolonged survival time, improved the cardiac function, alleviated the damages of liver, kidney and lung following sepsis in rats. The proteomics of myocardial tissue showed that differently expressed proteins between MR and LR infusion involved oxidative phosphorylation, apoptosis. Further study found that MR decreased ROS, improved the mitochondrial morphology and function, and ultimately enhanced mitochondrial respiration and promoted ATP production. Moreover, MR infusion decreased the expression of apoptosis-related proteins and increased the expression of anti-apoptotic proteins. TPP@PAMAM@MA was a polymer formed by wrapping L-malic acid with poly amido amine (PAMAM) modified triphenylphosphine material. TPP@PAMAM-MR (TPP-MR), which was synthesized by replacing the L-malic acid of MR with TPP@PAMAM@MA, was more efficient in targeting myocardial mitochondria and was superior to MR in protecting the sepsis-inducing myocardial injury. CONCLUSION: MR was suitable for protecting myocardial injury after sepsis. The mechanism was related to MR improving the function and morphology of cardiomyocyte mitochondria and inhibiting cardiomyocyte apoptosis. The protective effect of TPP-MR was superior to MR.

The protective effects of pericyte-derived microvesicles on vascular endothelial functions via CTGF delivery in sepsis.

BACKGROUND: It is well known that sepsis is a prevalent severe disease caused by infection and the treatment strategies are limited. Recently pericyte-derived microvesicles (PMVs) were confirmed to be therapeutic in many diseases, whether PMVs can protect vascular endothelial cell (VEC) injury is unknown. METHODS: Pericytes were extracted from the retina of newly weaned rats, and PMVs were collected after starvation and characterized by flow-cytometry and transmission electron microscopy. First, the effect of PMVs on pulmonary vascular function in septic rats was measured via intravenous administration with HE staining, immunofluorescence, and Elisa analysis. Then, PMVs were co-incubated with VECs in the presence of lipopolysaccharide (LPS), and observed the protective effect of PMVs on VECs. Next, the proteomic analysis and further Gene Ontology (GO) enrichment analysis were performed to analyze the therapeutic mechanism of PMVs, and the angiogenesis-related protein CTGF was highly expressed in PMVs. Finally, by CTGF upregulation and downregulation in PMV, the role of PMV-carried CTGF was investigated. RESULTS: PMVs restored the proliferation and angiogenesis ability of pulmonary VECs, and alleviated pulmonary vascular leakage in septic rats and LPS-stimulated VECs. Further study showed that PMVs delivered CTGF to VECs, and subsequently activated ERK1/2, and increased the phosphorylation of STAT3, thereby improving the function of VECs. The further study found CD44 mediated the absorption and internalization of PMVs to VECs, the anti-CD44 antibody inhibited the protective effect of PMVs. CONCLUSIONS: PMVs may delivery CTGF to VECs, and promote the proliferation and angiogenesis ability by activating the CTGF-ERK1/2-STAT3 axis, thereby protecting pulmonary vascular function in sepsis. The therapeutic effect of PMVs was highly related to CD44-mediated absorption. Video Abstract.

Role of AQP3 in the Vascular Leakage of Sepsis and the Protective Effect of Ss-31.

ABSTRACT: Aquaporins (AQPs) are a group of membrane proteins related to water permeability. Studies have shown that AQPs play a vital role in various diseases. Whether AQPs participate in regulating vascular permeability after sepsis and whether the subtype of AQPs is related are unknown. Ss-31, as a new antioxidant, had protective effects on a variety of diseases. However, whether Ss-31 has a protective effect on pulmonary vascular permeability in sepsis and whether its effect is related to AQPs are unclear. Using the cecum ligation perforation-induced septic rat and LPS-treated pulmonary vein endothelial cells, the role of AQPs in the regulation of the permeability of pulmonary vascular and its relationship to Ss-31 were studied. The results showed that the pulmonary vascular permeability significantly increased after sepsis, meanwhile the expressions of AQP3, 4, and 12 increased. Among those, the AQP3 was closely correlated with pulmonary vascular permeability. The inhibition of AQP3 antagonized the increase of the permeability of monolayer pulmonary vein endothelial cells. Further study showed that the expression of caveolin-1 (Cav-1) increased and occludin decreased after sepsis. The inhibition of AQP3 antagonized the decrease of Cav-1 and the increase of occludin in sepsis. Antioxidant Ss-31 decreased the expression of AQP3 and ROS levels. At the same time, Ss-31 improved pulmonary vascular permeability and prolonged survival of sepsis rats. In conclusion, AQP3 participates in the regulation of pulmonary vascular permeability after sepsis, and the antioxidant Ss-31 has a protective effect on pulmonary vascular permeability by downregulating the expression of AQP3 and inhibiting ROS production.

Synergistic effects of EMPs and PMPs on pulmonary vascular leakage and lung injury after ischemia/reperfusion.

BACKGROUND: Vascular leakage is an important pathophysiological process of critical conditions such as shock and ischemia-reperfusion (I/R)-induced lung injury. Microparticles (MPs), including endothelial cell-derived microparticles (EMPs), platelet-derived microparticles (PMPs) and leukocyte-derived microparticles (LMPs), have been shown to participate in many diseases. Whether and which of these MPs take part in pulmonary vascular leakage and lung injury after I/R and whether these MPs have synergistic effect and the underlying mechanism are not known. METHODS: Using hemorrhage/transfusion (Hemo/Trans) and aorta abdominalis occlusion-induced I/R rat models, the role of EMPs, PMPs and LMPs and the mechanisms in pulmonary vascular leakage and lung injury were observed. RESULTS: The concentrations of EMPs, PMPs and LMPs were significantly increased after I/R. Intravenous administration of EMPs and PMPs but not LMPs induced pulmonary vascular leakage and lung injury. Furthermore, EMPs induced pulmonary sequestration of platelets and promoted more PMPs production, and played a synergistic effect on pulmonary vascular leakage. MiR-1, miR-155 and miR-542 in EMPs, and miR-126 and miR-29 in PMPs, were significantly increased after hypoxia/reoxygenation (H/R). Of which, inhibition of miR-155 in EMPs and miR-126 in PMPs alleviated the detrimental effects of EMPs and PMPs on vascular barrier function and lung injury. Overexpression of miR-155 in EMPs down-regulated the expression of tight junction related proteins such as ZO-1 and claudin-5, while overexpression of miR-126 up-regulated the expression of caveolin-1 (Cav-1), the trans-cellular transportation related protein such as caveolin-1 (Cav-1). Inhibiting EMPs and PMPs production with blebbistatin (BLE) and amitriptyline (AMI) alleviated I/R induced pulmonary vascular leakage and lung injury. CONCLUSIONS: EMPs and PMPs contribute to the pulmonary vascular leakage and lung injury after I/R. EMPs mediate pulmonary sequestration of platelets, producing more PMPs to play synergistic effect. Mechanically, EMPs carrying miR-155 that down-regulates ZO-1 and claudin-5 and PMPs carrying miR-126 that up-regulates Cav-1, synergistically mediate pulmonary vascular leakage and lung injury after I/R. Video Abstract.

Relationship of Cx43 regulation of vascular permeability to osteopontin-tight junction protein pathway after sepsis in rats.

Our previous study demonstrated that connexin (Cx)43 participated in the regulation of vascular permeability in severe sepsis. Osteopontin (OPN) has been demonstrated to participate in the occurrence of atherosclerosis, inflammation, as well as the adhesion and migration of cells. It is not clear whether OPN is involved in Cx43 regulating vascular permeability after sepsis and if it is related to tight-junction proteins. with the use of cecal ligation and puncture (CLP)-induced septic rats and lipopolysaccharide (LPS)-treated pulmonary vein vascular endothelial cells (VECs), the role of zona occuldens 1 (ZO-1) and claudin-5 in Cx43 regulation of vascular permeability and its relationship to OPN were investigated in the present study. The results showed that the expression of ZO-1 and claudin-5 in pulmonary vein were decreased in CLP rats and LPS-treated pulmonary vein VECs. Cx43-overexpressed lentivirus induced the degradation of ZO-1 and claudin-5, while Cx43 RNAi lentivirus abrogated the degradation of ZO-1 and claudin-5 induced by LPS. The vascular permeability and expression of OPN in pulmonary veins were significantly increased in CLP rats and LPS-treated pulmonary vein VECs. Silencing OPN by OPN RNAi lentivirus inhibited the vascular hyperpermeability induced by LPS. Overexpressed Cx43 lentivirus increased the expression of OPN and vascular permeability and downregulated the expression of ZO-1 and claudin-5 in pulmonary vein VECs. Silencing OPN by OPN RNAi lentivirus inhibited the effects of Cx43-overexpressed lentivirus on downregulation of ZO-1 and claudin-5 and vascular hyperpermeability in pulmonary vein VECs. Transfection of specific double-stranded RNA targeting to ß-catenin and T-cell factor-4 (Tcf-4) abolished the upregulation of OPN induced by Cx43 overexpression. These results suggest that OPN participates in the regulation of vascular permeability by Cx43 after sepsis. Cx43 upregulation of OPN is via the Tcf-4/ß-catenin transcription pathway; OPN increases vascular permeability by downregulating the expression of the tight junction proteins ZO-1 and claudin-5.

Involvement of connexin 43 phosphorylation and gap junctional communication between smooth muscle cells in vasopressin-induced ROCK-dependent vasoconstriction after hemorrhagic shock.

We examined the roles played by gap junctions (GJs) and the GJ channel protein connexin 43 (Cx43) in arginine vasopressin (AVP)-induced vasoconstriction after hemorrhagic shock and their relationship to Rho kinase (ROCK) and protein kinase C (PKC). The results showed that AVP induced an endothelium-independent contraction in rat superior mesenteric arteries (SMAs). Blocking the GJs significantly decreased the contractile response of SMAs and vascular smooth muscle cells (VSMCs) to AVP after shock and hypoxia. The selective Cx43-mimetic peptide inhibited the vascular contractile effect of AVP after shock and hypoxia. AVP restored hypoxia-induced decrease of Cx43 phosphorylation at Ser262 and gap junctional communication in VSMCs. Activation of RhoA with U-46619 increased the contractile effect of AVP. This effect was antagonized by the ROCK inhibitor Y27632 and the Cx43-mimetic peptide. In contrast, neither an agonist nor an inhibitor of PKC had significant effects on AVP-induced contraction after hemorrhagic shock. In addition, silencing of Cx43 with siRNA blocked the AVP-induced increase of ROCK activity in hypoxic VSMCs. In conclusion, AVP-mediated vascular contractile effects are endothelium and myoendothelial gap junction independent. Gap junctions between VSMCs, gap junctional communication, and Cx43 phosphorylation at Ser262 play important roles in the vascular effects of AVP. RhoA/ROCK, but not PKC, is involved in this process.

4-Phenylbutyrate Benefits Traumatic Hemorrhagic Shock in Rats by Attenuating Oxidative Stress, Not by Attenuating Endoplasmic Reticulum Stress.

OBJECTIVE: Vascular dysfunction such as vascular hyporeactivity following severe trauma and shock is a major cause of death in injured patients. Oxidative stress and endoplasmic reticulum stress play an important role in vascular dysfunction. The objective of the present study was to determine whether or not 4-phenylbutyrate can improve vascular dysfunction and elicit antishock effects by inhibiting oxidative and endoplasmic reticulum stress. DESIGN: Prospective, randomized, controlled laboratory experiment. SETTING: State key laboratory of trauma, burns, and combined injury. SUBJECTS: Five hundred and fifty-two Sprague-Dawley rats. INTERVENTIONS: Rats were anesthetized, and a model of traumatic hemorrhagic shock was established by left femur fracture and hemorrhage. The effects of 4-phenylbutyrate (5, 20, 50, 100, 200, and 300 mg/kg) on vascular reactivity, animal survival, hemodynamics, and vital organ function in traumatic hemorrhagic shock rats and cultured vascular smooth muscle cells, and the relationship to oxidative stress and endoplasmic reticulum stress was observed. MEASUREMENTS AND MAIN RESULTS: Lower doses of 4-phenylbutyrate significantly improved the vascular function, stabilized the hemodynamics, and increased the tissue blood flow and vital organ function in traumatic hemorrhagic shock rats, and markedly improved the survival outcomes. Among all dosages observed in the present study, 20 mg/kg of 4-phenylbutyrate had the best effect. Further results indicated that 4-phenylbutyrate significantly inhibited the oxidative stress, decreased shock-induced oxidative stress index such as the production of reactive oxygen species, increased the antioxidant enzyme levels such as superoxide dismutase, catalase, and glutathione, and improved the mitochondrial function by inhibiting the opening of the mitochondrial permeability transition pore in rat artery and vascular smooth muscle cells. In contrast, 4-phenylbutyrate did not affect the changes of endoplasmic reticulum stress markers following traumatic hemorrhagic shock. Furthermore, 4-phenylbutyrate increased the nuclear levels of nuclear factor-E2-related factor 2, and decreased the nuclear levels of nuclear factor κB in hypoxic vascular smooth muscle cells. CONCLUSIONS: 4-phenylbutyrate has beneficial effects for traumatic hemorrhagic shock including improving animal survival and protecting organ function. These beneficial effects of 4-phenylbutyrate in traumatic hemorrhagic shock result from its vascular function protection via attenuation of the oxidative stress and mitochondrial permeability transition pore opening. Nuclear factor-E2-related factor 2 and nuclear factor-κB may be involved in 4-phenylbutyrate-mediated inhibition of oxidative stress.

Role of connexin 43 in vascular hyperpermeability and relationship to Rock1-MLC20 pathway in septic rats.

Connexin (Cx)43 has been shown to participate in several cardiovascular diseases. Increased vascular permeability is a common and severe complication in sepsis or septic shock. Whether or not Cx43 takes part in the regulation of vascular permeability in severe sepsis is not known, and the underlying mechanism has not been described. With cecal ligation and puncture-induced sepsis in rats and lipopolysaccharide (LPS)-treated vascular endothelial cells (VECs) from pulmonary veins, the role of Cx43 in increased vascular permeability and its relationship to the RhoA/Rock1 pathway were studied. It was shown that vascular permeability in the lungs, kidneys, and mesentery in sepsis rats and LPS-stimulated monolayer pulmonary vein VECs was significantly increased and positively correlated with the increased expression of Cx43 and Rock1 in these organs and cultured pulmonary vein VECs. The connexin inhibitor carbenoxolone (10 mg/kg iv) and the Rock1 inhibitor Y-27632 (2 mg/kg iv) alleviated the vascular leakage of lung, mesentery, and kidney in sepsis rats. Overexpressed Cx43 increased the phosphorylation of 20-kDa myosin light chain (MLC20) and the expression of Rock1 and increased the vascular permeability and decreased the transendothelial electrical resistance of pulmonary vein VECs. Cx43 RNA interference decreased the phosphorylation of MLC20 and the expression of Rock1 and decreased LPS-stimulated hyperpermeability of cultured pulmonary vein VECs. The Rock1 inhibitor Y-27632 alleviated LPS- and overexpressed Cx43-induced hyperpermeability of monolayer pulmonary vein VECs. This report shows that Cx43 participates in the regulation of vascular permeability in sepsis and that the mechanism is related to the Rock1-MLC20 phosphorylation pathway.

Beneficial effect of cyclosporine A on traumatic hemorrhagic shock.

BACKGROUND: Vascular hyporeactivity plays an important role in severe trauma and shock. We investigated the beneficial effect of cyclosporine A (CsA) on traumatic shock and its relationship to vascular reactivity improvement and mitochondrial permeability transition pore (MPTP). MATERIALS AND METHODS: Sodium pentobarbital-anesthetized rats were used to induce traumatic hemorrhagic shock by left femur fracture and hemorrhage, the beneficial effects of CsA (1, 5, and 10 mg/kg, intravenously) on animal survival, cardiovascular function, tissue blood perfusion, and mitochondrial function of vital organs were observed. In addition, hypoxia-treated vascular smooth muscle cells from normal rats were used to investigate the relationship of this beneficial effect of CsA to Rho-associated serine/threonine kinase (ROCK) and protein kinase C. RESULTS: CsA prolonged the survival time and increased the 24-h survival rate of traumatic hemorrhagic shock (31%, 56%, and 56% in 1, 5, and 10 mg/kg CsA group versus 25% in lactated Ringer solution group). Five milligrams per kilogram of CsA had the best effect, which stabilized and improved the hemodynamics, increased the tissue blood flow, and improved the liver and kidney function including its mitochondrial function in shock rats. CsA had no significant influences on the production of inflammatory mediators and cardiac output after traumatic hemorrhagic shock. Further results indicated that CsA significantly improved the vascular constriction and dilation reactivity of superior mesenteric artery to norepinephrine and acetylcholine, which was antagonized by ROCK inhibitor, Y27632, but not by protein kinase C inhibitor, staurosporine. Further studies showed that CsA restored hypoxia-induced decrease of ROCK activity and inhibited the opening of MPTP in hypoxia-treated vascular smooth muscle cells. CONCLUSIONS: CsA is beneficial for the treatment of traumatic hemorrhagic shock. The mechanism is mainly through improving the vascular reactivity, stabilizing the hemodynamics, and increasing tissue perfusion. This beneficial effect of CsA is related to the inhibitory effect of CsA on MPTP opening. ROCK is an important regulator molecule in this process.

Bradykinin induces vascular contraction after hemorrhagic shock in rats.

BACKGROUND: Bradykinin (BK) has many biological effects in inflammation, allergy, and septic shock. Studies have shown that low doses of BK can induce vascular relaxation and high doses can induce vascular contraction in many pathophysiological conditions, but the role and mechanisms that high doses of BK have on vascular contraction in hemorrhagic shock are not clear. METHODS: With hemorrhagic-shock rats and hypoxia-treated superior mesenteric artery (SMA), we investigated the role and mechanisms of high doses of BK-induced vascular contraction in hemorrhagic shock. RESULTS: High doses of BK (500-50,000 ng/kg in vivo or 10(-10) to 10(-5) mol/L in vitro) dose dependently induced vascular contraction of SMA and increased the vascular calcium sensitivity in normal and hemorrhagic-shock rats. Less than 10(-10) mol/L of BK induced vascular dilation BK-induced increase of vascular contractile response and calcium sensitivity was reduced by denudation of the endothelium, 18α-glycyrrhetic acid (an inhibitor of myoendothelial gap junction) and connexin 43 antisense oligodeoxynucleotide. Further studies found that high concentrations of BK-induced vascular contraction in hemorrhagic shock was closely related to the activation of Rho A-Rho kinase pathway and Protein Kinase C (PKC) α and ε. CONCLUSIONS: High doses of BK can induce vascular contraction in hemorrhagic shock condition, which is endothelium and myoendothelial gap junction dependent. Cx43-mediated activation of Rho A-Rho kinase and Protein Kinase C (PKC) pathway plays a very important role in this process. This finding provided a new angle of view to the biological role of BK in other pathophysiological conditions such as hemorrhagic shock or hypoxia.

Age and sex differences in vascular responsiveness in healthy and trauma patients: contribution of estrogen receptor-mediated Rho kinase and PKC pathways.

Several medical conditions exhibit age- and sex-based differences. Whether or not traumatic shock exhibits such differences with regard to vascular responsiveness is not clear. In a cohort of 177 healthy subjects and 842 trauma patients (21-82 years) as well as different ages (4, 8, 10, 14, 18, and 24 wk; 1 and 1.5 years) and sexes of Sprague-Dawley normal and traumatic shock rats, the age- and sex-based differences of vascular responsiveness and the underlying mechanisms were investigated. Middle-aged and young women as well as female rats of reproductive age had higher vascular responsiveness in the normal condition and a lower decrease in vascular responsiveness after traumatic shock than older men and male rats of identical age. Exogenous supplementation of 17ß-estrdiol increased vascular reactivity in both male and femal rats of 8-24 wk and preserved vascular responsiveness in rats following traumatic shock. No effect was observed in rats 1 to 1.5 years. These protective effects of estrogen were closely related to G protein-coupled receptor (GPR)30, estrogen receptor-mediated Rho kinase, and PKC pathway activation. Vascular responsiveness exhibits age- and sex-based differences in healthy subjects and trauma patients. Estrogen and its receptor (GPR30) mediated activation of Rho kinase and PKC using genomic and nongenomic mechanisms to elicit protective effects in vascular responsiveness. This finding is important for the personalized treatment for several age- and sex-related diseases involving estrogen.

Beneficial effects of platelet-derived growth factor on hemorrhagic shock in rats and the underlying mechanisms.

Studies have shown that local application of platelet-derived growth factor (PDGF) can be used for the treatment of acute and chronic wounds. We investigated if systemic application of PDGF has a protective effect on acute hemorrhagic shock in rats in the present study. Using hemorrhagic shock rats and isolated superior mesenteric arteries, the effects of PDGF-BB on hemodynamics, animal survival, and vascular reactivity as well as the roles of the gap junction proteins connexin (Cx)40 and Cx43, PKC, and Rho kinase were observed. PDGF-BB (1­15 µg/kg iv) significantly improved the hemodynamics and blood perfusion to vital organs (liver and kidney) as well as vascular reactivity and improved the animal survival in hemorrhagic shock rats. PDGF recovering shock-induced vascular hyporeactivity depended on the integrity of the endothelium and myoendothelial gap junction. Cx43 antisense oligodeoxynucleotide abolished these improving effects of PDGF, whereas Cx40 oligodeoxynucleotide did not. Further study indicated that PDGF increased the activity of Rho kinase and PKC as well as vascular Ca2+ sensitivity, whereas it did not interfere with the intracellular Ca2+ concentration in hypoxia-treated vascular smooth muscle cells. In conclusion, systemic application of PDGF-BB may exert beneficial effects on hemorrhagic shock, which are closely related to the improvement of vascular reactivity and hemodynamics. The improvement of PDGF-BB in vascular reactivity is vascular endothelium and myoendothelial gap junction dependent. Cx43, Rho kinase, and PKC play very important role in this process. These findings suggest that PDGF may be a potential measure to treat acute clinical critical diseases such as severe trauma, shock, and sepsis.

Role of non-MLC20 phosphorylation pathway in the regulation of vascular reactivity during shock.

BACKGROUND: Studies have shown that shock-induced vascular hyporeactivity is associated with the decrease in 20-kDa myosin light chain (MLC20) phosphorylation. Whether and how a non-MLC20 phosphorylation pathway participates in the regulation of vascular reactivity after shock is not known. METHODS: With superior mesentery artery (SMA) obtained from rats in hemorrhagic shock and hypoxia-treated SMA, the regulatory effect of platelet-derived growth factor (PDGF) on vascular reactivity and the roles of caldesmon, 27-kDa heat shock protein (HSP27), extracellular signal-regulated protein kinase (Erk), and p38 mitogen-activated protein kinase (MAPK), the main molecules that are involved in the non-MLC20 phosphorylation pathway of the regulation of smooth-muscle contraction, were investigated. RESULTS: PDGF (40-100 ng/mL) increased the vascular reactivity after shock in a dose-dependent manner, whereas it did not increase the MLC20 phosphorylation in a dose-dependent manner. PDGF with concentration more than 60 ng/mL did not further increase the MLC20 phosphorylation, whereas upregulated the phosphorylation of HSP27, Erk, and p38MAPK, and the activity of myosin adenosine triphosphatase in SMAs, and downregulated the phosphorylation of caldesmon. p38MAPK antagonist, SB203580, not only antagonized PDGF-induced increase in the phosphorylation of HSP27, but also antagonized PDGF-induced decrease in the phosphorylation of caldesmon, whereas Erk antagonist, PD98059, only antagonized PDGF-induced decrease in the phosphorylation of caldesmon. CONCLUSIONS: These findings suggested that a non-MLC20 phosphorylation pathway participated in the regulation of vascular reactivity after shock. Caldesmon- and HSP27-mediated change in myosin adenosine triphosphatase activity and Erk and p38MAPK played an important role in this process. These findings may provide some potential targets for the treatment of vascular hyporeactivity after shock.

Role of Excessive Mitochondrial Fission in Seawater Immersion Aggravated Hemorrhagic Shock-Induced Cardiac Dysfunction and the Protective Effect of Mitochondrial Division Inhibitor-1.

Aims: Seawater immersion significantly aggravated organ dysfunction following hemorrhagic shock, leading to higher mortality rate. However, the effective treatment is still unavailable in clinic. Mitochondria were involved in the onset and development of multiple organ function disorders; whether mitochondria participate in the cardiac dysfunction following seawater immersion combined with hemorrhagic shock remains poorly understood. Hence, we investigated the role and possible mechanism of mitochondria in seawater immersion combined with hemorrhage shock-induced cardiac dysfunction. Results: Mitochondrial fission protein dynamin-related protein 1 (Drp1) was activated and translocated from the cytoplasm to mitochondria in the heart following seawater immersion combined with hemorrhagic shock, leading to excessive mitochondrial fission. Excessive mitochondrial fission disrupted mitochondrial function and structure and activated mitophagy and apoptosis. At the same time, excessive mitochondrial fission resulted in disturbance of myocardial structure and hemodynamic disorders and ultimately provoked multiple organ dysfunction and high mortality. Further studies showed that the mitochondrial division inhibitor mitochondrial division inhibitor-1 can significantly reverse Drp1 mitochondrial translocation and inhibit mitochondrial fragmentation, reactive oxygen species (ROS) accumulation, mitophagy, and apoptosis and then protect circulation and vital organ functions, prolonging animal survival. Innovation: Our findings indicate that Drp1-mediated mitochondrial fission could be a novel therapeutic targets for the treatment of seawater immersion combined with hemorrhagic shock. Conclusion: Drp1 mitochondrial translocation played an important role in the cardiac dysfunction after seawater immersion combined with hemorrhage shock. Drp1-mediated excessive mitochondrial fission leads to cardiac dysfunction due to the mitochondrial structure and bioenergetics impairment.

The New Nano-Resuscitation Solution (TPP-MR) Attenuated Myocardial Injury in Hemorrhagic Shock Rats by Inhibiting Ferroptosis.

Background: Hemorrhagic shock was a leading cause of death worldwide, with myocardial injury being a primary affected organ. As commonly used solutions in fluid resuscitation, acetated Ringer's (AR) and Lactate Ringer's solution (LR) were far from perfect for their adverse reactions such as lactic acidosis and electrolyte imbalances. In previous studies, TPP@PAMAM-MR (TPP-MR), a novel nanocrystal resuscitation fluid has been found to protect against myocardial injury in septic rats. However, its role in myocardial injury in rats with hemorrhagic shock and underlying mechanism is unclear. Methods: The hemorrhagic shock rats and hypoxia-treated cardiomyocytes (H9C2) were utilized to investigate the impact of TPP-MR on cardiac function, mitochondrial function, and lipid peroxidation. The expressions of ferritin-related proteins glutathione peroxidase 4 (GPX4), Acyl CoA Synthase Long Chain Family Member 4 (ACSL4), and Cyclooxygenase-2(COX2) were analyzed through Western blotting to explore the mechanism of TPP-MR on hemorrhagic myocardial injury. Results: TPP-MR, a novel nanocrystalline resuscitation fluid, was synthesized using TPP@PAMAM@MA as a substitute for L-malic acid. We found that TPP-MR resuscitation significantly reduced myocardial injury reflected by enhancing cardiac output, elevating mean arterial pressure (MAP), and improving perfusion. Moreover, TPP-MR substantially prolonged hemorrhagic shock rats' survival time and survival rate. Further investigations indicated that TPP-MR improved the mitochondrial function of myocardial cells, mitigated the production of oxidative stress agents (ROS) and increased the glutathione (GSH) content. Additionally, TPP-MR inhibited the expression of the ferroptosis-associated GPX4 protein, ACSL4 and COX2, thereby enhancing the antioxidant capacity. Conclusion: The results showed that TPP-MR had a protective effect on myocardial injury in rats with hemorrhagic shock, and its mechanism might be related to improving the mitochondrial function of myocardial cells and inhibiting the process of ferroptosis.

Role of adenosine A2A receptor in organ-specific vascular reactivity following hemorrhagic shock in rats.

BACKGROUND: Previous studies have demonstrated differences among organs in terms of shock-induced vascular reactivity and a role for adenosine A2A receptors (A2ARs) in protection against ischemia/reperfusion injury. However, the contributions of A2ARs to organ-specific vascular reactivity and the protection of vascular responsiveness following shock are currently unknown. METHODS: We investigated the role of A2ARs in different arteries, including the left femoral artery (LFA), thoracic aorta (TA), superior mesenteric artery (SMA), right renal artery (RRA), pulmonary artery (PA), and middle cerebral artery (MCA), in hemorrhagic-shock rats. RESULTS: The vascular reactivities of the LFA, SMA, RRA, and MCA increased slightly during early shock and then gradually decreased, whereas those of the PA and TA decreased from the start of shock. Different blood vessels lost vascular reactivity at different rates compared with controls; the LFA had the highest rate of loss (64.51%), followed by the SMA (44.69%), TA (36.06%), PA (37.83%), and RRA (32.33%), whereas the MCA had the lowest rate (18.45%). The rate of loss of vascular reactivity in the different vessels was negatively correlated with A2AR expression levels in normal and shock conditions. The highly selective A2AR agonist CGS 21680 significantly improved vascular reactivity, hemodynamic parameters, and animal survival, whereas the specific antagonist SCH58261 further decreased the shock-induced reduction in vascular reactivity and hemodynamic parameters. CONCLUSIONS: A2ARs are involved in the regulation and protection of vascular reactivity following shock. A2AR activation may have a beneficial effect on hemorrhagic shock by improving vascular reactivity and hemodynamic parameters.

Ideal resuscitation pressure for uncontrolled hemorrhagic shock in different ages and sexes of rats.

INTRODUCTION: Our previous studies demonstrated that 50-60 mmHg mean arterial blood pressure was the ideal target hypotension for uncontrolled hemorrhagic shock during the active hemorrhage in sexually mature rats. The ideal target resuscitation pressure for immature and older rats has not been determined. METHODS: To elucidate this issue, using uncontrolled hemorrhagic-shock rats of different ages and sexes (6 weeks, 14 weeks and 1.5 years representing pre-adult, adult and older rats, respectively), the resuscitation effects of different target pressures (40, 50, 60, 70 and 80 mmHg) on uncontrolled hemorrhagic shock during active hemorrhage and the age and sex differences were observed. RESULTS: Different target resuscitation pressures had different resuscitation outcomes for the same age and sex of rats. The optimal target resuscitation pressures for 6-week-old, 14-week-old and 1.5-year-old rats were 40 to 50 mmHg, 50 to 60 mmHg and 70 mmHg respectively. Ideal target resuscitation pressures were significantly superior to other resuscitation pressures in improving the hemodynamics, blood perfusion, organ function and animal survival of uncontrolled hemorrhagic-shock rats (P < 0.01). For same target resuscitation pressures, the beneficial effect on hemorrhagic shock had a significant age difference (P < 0.01) but no sex difference (P > 0.05). Different resuscitation pressures had no effect on coagulation function. CONCLUSION: Hemorrhagic-shock rats at different ages have different target resuscitation pressures during active hemorrhage. The ideal target resuscitation hypotension for 6-week-old, 14-week-old and 1.5-year-old rats was 40 to 50 mmHg, 50 to 60 mmHg and 70 mmHg, respectively. Their resuscitation effects have significant age difference but had no sex difference.

Genistein, a Soybean Isoflavone, Promotes Wound Healing by Enhancing Endothelial Progenitor Cell Mobilization in Rats with Hemorrhagic Shock.

Severe trauma and hemorrhaging are often accompanied by delayed cutaneous wound healing. Soybean isoflavone is a natural phytoestrogen that has attracted great attention due to its protective effects against various injuries. Endothelial progenitor cells (EPCs) are precursor cells with directional differentiation characteristics. This study is to determine whether genistein (GEN), an isoflavone in soybean products, benefits wound healing in hemorrhagic shock (HS) rats by promoting EPC homing and to investigate the underlying mechanisms. In this study, it is found that GEN promotes skin wound healing in HS rats, which is due at least partly to the mobilization of endogenous EPCs to the injury site via angiotensin II (Ang-II), stromal cell-derived factor-1alpha (SDF-1α), and transforming growth factor beta(TGF-ß) signaling.

Protective Effect of Modified Hemoglobin on Rabbits and Goats in High-Altitude Sickness.

The prevalence and severity of high-altitude sickness increases with increasing altitude. Prevention of hypoxia caused by high-altitude sickness is an urgent problem. As a novel oxygen-carrying fluid, modified hemoglobin can carry oxygen in a full oxygen partial pressure environment and release oxygen in a low oxygen partial pressure environment. It is unclear whether modified hemoglobin can improve hypoxic injury on a plateau. Using hypobaric chamber rabbit (5000 m) and plateau goat (3600 m) models, general behavioral scores and vital signs, hemodynamic, vital organ functions, and blood gas are measured. The results show that the general behavioral scores and vital signs decrease significantly in the hypobaric chamber or plateau, and the modified hemoglobin can effectively improve the general behavioral scores and vital signs in rabbits and goats, and reduce the degree of damage to vital organs. Further studies reveal that arterial partial pressure of oxygen (PaO2 ) and arterial oxygen saturation (SaO2 ) on the plateau decrease rapidly, and the modified hemoglobin could increase PaO2 and SaO2 ; thus, increasing the oxygen-carrying capacity. Moreover, modified hemoglobin has few side effects on hemodynamics and kidney injury. These results indicate that modified hemoglobin has a protective effect against high-altitude sickness.