Hemorrhage In Rats Research Articles

The role of the sympathetic nervous system in the resuscitative effect of stimulating the central serotonin 1A receptors in haemorrhagic shock in rats

Haemorrhagic shock is a life threatening condition, and, as such, it is important to understand the mechanisms taking part in its reversal. In the 1990s, it was shown that activation of serotonin 1A receptors is responsible for the circulatory decompensation and development of the sympathoinhibitory phase. In previous reports, it was demonstrated that activation of serotonin 1A receptors induces resuscitative effects in haemorrhaged rats. However, the effectory mechanisms still require further investigation. The aim of the present study was to determine whether the sympathetic nervous system participates in the effects of serotonin through central serotonin 1A receptors in haemorrhagic shock in rats. In order to determine the role of the sympathetic nervous system alpha-1-, alpha-2-, and beta-adrenergic receptor agonists – prazosin, yohimbine and propranolol, respectively, were used. We found that stimulation of the central serotonin 1A receptors by the administration of a selective agonist – 8-hydroxy-2-(di-n-propylamino)tetralin, 1-(2,5-dimethoxy-4-iodophenyl)-aminopropane (8-OH-DPAT) into the lateral brain ventricle is connected with the activation of compensation mechanisms leading to the increase in the heart rate and blood pressure. The current results demonstrate that the stimulation of peripheral alpha-1-, alpha-2- and beta-adrenergic receptors plays an essential role in the resuscitative effect triggered by the stimulation of central serotonin 1A receptors.

P-Hydroxyphenylpyruvate, an Intermediate of the Phe/Tyr Catabolism, Improves Mitochondrial Oxidative Metabolism under Stressing Conditions and Prolongs Survival in Rats Subjected to Profound Hemorrhagic Shock

The aim of this study was to test the effect of a small volume administration of p-hydroxyphenylpyruvate (pHPP) in a rat model of profound hemorrhagic shock and to assess a possible metabolic mechanism of action of the compound. The results obtained show that hemorrhaged rats treated with 2–4% of the estimated blood volume of pHPP survived significantly longer (p<0.001) than rats treated with vehicle. In vitro analysis on cultured EA.hy 926 cells demonstrated that pHPP improved cell growth rate and promoted cell survival under stressing conditions. Moreover, pHPP stimulated mitochondria-related respiration under ATP-synthesizing conditions and exhibited antioxidant activity toward mitochondria-generated reactive oxygen species. The compound effects reported in the in vitro and in vivo analyses were obtained in the same millimolar concentration range. These data disclose pHPP as an efficient energetic substrates-supplier to the mitochondrial respiratory chain as well as an antioxidant supporting the view that the compound warrants further evaluation as a therapeutic agent.

Bkca opener, NS1619 pretreatment protects against shock-induced vascular hyporeactivity through PDZ-Rho GEF–RhoA–Rho kinase pathway in rats

Our previous study showed that the ischemic preconditioning and pretreatment of adenosine triphosphate-sensitive potassium channel (KATP) opener, pinacidil, may induce a good protective effect on shock-induced vascular hyporeactivity. Whether the pretreatment of opener/activator of the large-conductance calcium-activated potassium channel (Bkca), NS1619, can also induce a protective effect on vascular reactivity and play a beneficial effect on subsequent hemorrhagic shock is not clear. With Sprague-Dawley rats subjected to hemorrhagic shock and their isolated superior mesenteric artery, the protective effect of NS1619 (0.5, 1, 2, and 4 mg/kg) pretreatment (30 minutes before hemorrhage shock) on vascular reactivity and the underlying mechanisms were observed. NS1619 pretreatment significantly improved the 72-hour survival of hemorrhagic shock rats, alleviated shock-induced decrease of vascular reactivity and calcium sensitivity, and increased the cardiac output and oxygen delivery. NS1619 2 mg/kg had the best effect. These protective effects of NS1619 pretreatment on vascular reactivity and calcium sensitivity were antagonized by RhoA inhibitor, C3 transferase, and Rho kinase antagonist, Y-27632. NS1619 pretreatment up-regulated the activities of RhoA, Rho-kinase, and PDZ-Rho GEF (guanine nucleotide exchange factor). These effects of NS1619 pretreatment were eliminated by RhoA inhibitor, C3 transferase. Bkca opener, NS1619 pretreatment has good protective effect on vascular reactivity and calcium sensitivity, which plays a good beneficial effect on hemorrhagic shock. The mechanism may be mainly through PDZ-Rho GEF-RhoA-Rho kinase pathway. Bkca channel may be a potential target for the treatment of shock-induced vascular hyporeactivity.

Effects of oral pyruvate-glucose-electrolyte solution on organ function and survival in resuscitation of lethal hemorrhagic shock rats

Objective To study the effects of oral rehydration with the solution of pyruvate-glucoseelectrolyte (PGES) by comparison with the bicarbonate-glucose-electrolyte solution (BGES) on resuscitation in rats with lethal hemorrhagic shock.Methods Sixty adult male SD rats with intra-gastric tube,and cannulation of femoral artery and vein were subjected to 45％ total blood volume loss from the femoral artery,and then randomly divided into three groups (n =20 in each group):no fluid resuscitation group (NR),oral fluid resuscitation with the PGES group (PGES) and oral fluid resuscitation with the BGES group (BGES).In NR group,the animals received no fluid replacement or any other treatment.Rats in PGES and BGES groups were infused intra-gastrically with pre-warmed PGES or BGES in volume of 2 times shed blood given at 30 min after hemorrhage and completed within 6 hours.Blood samples in each group were collected from the abdominal aorta before or at 0,1,2,4 h post hemorrhage to detect serum alanine aminotransferase (ALT),creatinine (Cr),creatine phosphate kinase isoenzyme (CK-MB) and intestinal fatty acid binding protein (iFABP).Another 84 rats randomly divided into four groups:NR group (n =24),PGES group (n =24),BGES group (n =24),and no hemorrhage group (NH group,n =12).Rats in the three hemorrhage groups were treated the same as described above,and the rats in NH group underwent the same surgical procedure without hemorrhage were served as the sham group.All these rats were observed for their 24-hour survival rates.Results The 24-hour survival rates of PGES and BGES groups were both significantly higher than the rate of NR group (11/24 vs.1/24,x2 =18.087,P ＜0.01 ; 5/24 vs.1/24,x2 =6.445,P ＜ 0.05) ; the survival rate of PGES group was also significantly higher than that of BGES group (11/24 vs.5/24,x2 =4.02,P ＜ 0.05).All levels of ALT,CK-MB,Cr and iFABP in both the NR group and two oral resuscitation groups at 1 h,2 h and 4 h post hemorrhage were significantly higher than those before the blood loss,respectively (P ＜ 0.01).These biomarkers at 2 h,4 h post hemorrhage were significantly lower in the PGES and BGES groups than those in NR group (P ＜ 0.01) ; the serum levels of ALT,CK-MB,Cr and iFABP were significantly lower in the PGES group than those in the BGES group at 2 h and 4 h post hemorrhage,respectively (P ＜ 0.05).Conclusions Present results demonstrated that the pyruvate-enriched oral re-hydration solution (ORS =PGES) was more effective in preserving the organ function and prolonging the animal survival after resuscitation of lethal hemorrhagic shock in comparison with the bicarbonate-containing ORS (BGES).The oral re-hydration solution (PGES) recommended by the World Hygiene Organization (WHO ORS) may require further improvement in oral resuscitation of shock and the PGES may be recommended as a choice of oral re-hydration salts in the treatment of lethal hemorrhagic shock when intravenous administration is not available. Key words: Hemorrhage ; Shock ; Oral rehydration ; Pyruvate ; Intestinal fatty acid binding protein ; Survival

Effects of aminoguanidine, a potent nitric oxide synthase inhibitor, on myocardial and organ structure in a rat model of hemorrhagic shock.

Background:Nitric oxide (NO) has been shown to increase following hemorrhagic shock (HS). Peroxynitrite is produced by the reaction of NO with reactive oxygen species, leads to nitrosative stress mediated organ injury. We examined the protective effects of a potent inhibitor of NO synthase, aminoguanidine (AG), on myocardial and multiple organ structure in a rat model of HS.Materials and Methods:Male Sprague Dawley rats (300-350 g) were assigned to 3 experimental groups (n = 6 per group): (1) Normotensive rats (N), (2) HS rats and (3) HS rats treated with AG (HS-AG). Rats were hemorrhaged over 60 min to reach a mean arterial blood pressure of 40 mmHg. Rats were treated with 1 ml of 60 mg/kg AG intra-arterially after 60 min HS. Resuscitation was performed in vivo by the reinfusion of the shed blood for 30 min to restore normo-tension. Biopsy samples were taken for light and electron microscopy.Results:Histological examination of hemorrhagic shocked untreated rats revealed structural damage. Less histological damage was observed in multiple organs in AG-treated rats. AG-treatment decreased the number of inflammatory cells and mitochondrial swollen in myocardial cells.Conclusion:AG treatment reduced microscopic damage and injury in multiple organs in a HS model in rats.

Correlation between serum IL-1beta levels and cerebral edema extent in a hypertensive intracerebral hemorrhage rat model

Background: Interleukin-1beta (IL-1beta) is a pro-inflammatory cytokine that is increased following hypertensive intracerebral hemorrhage (ICH), potentially related to neural damage by cerebral edema.Objective: To investigate the correlation between post-ICH serum IL-1beta and cerebral edema in a hypertensive rat model.Methods: We used 30 successful ICH male spontaneously hypertensive rats (SHR) subjected to autologous blood infusion and displaying behavioral abnormalities (ICH group), and 30 sham-operated rats. Cerebral edema was assessed at 8, 16, 24, 48, 72, and 120 hours using dry and wet right hemisphere weighing, and serum IL-1beta levels were determined by enzyme-linked immunosorbent assay (ELISA). Nonlinear regression was performed between serum IL-1beta levels and cerebral edema extent at different time intervals after ICH.Results: No significant difference was observed in preoperative blood pressure between the two groups. In ICH rats, behavioral abnormalities were observed at all time points except at 120 hours Intracerebral hemorrhage rats exhibited significantly increased serum IL-1beta levels between 16 and 72 hours, and increased cerebral edema between 24 and 72 hours (all P < 0·05 vs sham-operated rats), but no significant differences were found in the sham-operated group. Serum IL-1beta and cerebral edema in the ICH group returned to baseline by 120 hours Serum IL-1beta levels were positively correlated with cerebral edema (r = 0·906, P = 0·001).Conclusion: Serum IL-1beta was related to cerebral edema extent in hypertensive ICH rats, which may eventually be useful as an indicator for progression of cerebral edema after ICH, and contributing to the choice of a treatment strategy.

Abstract 184: Inhibition of Nitric Oxide Synthase Attenuate Hemorrhage Induced Inflammatory Response and Protect Against Multiple Organ Injury in a Rat Model

Hemorrhagic shock activates inflammatory pathways and results in upregulation of cytokine synthesis. Nitric oxide has been implicated in the pathophysiology of hemorrhagic shock. Objectives: We have investigated the protective effects of inhibition of inducible nitric oxide synthase (iNOS) using N G - nitro-L-arginine methyl ester (L-NAME) on preventing organ injury in a rat model of hemorrhagic shock and resuscitation. Methods: Male Sprague Dawley rats (300-350 gm) were assigned to 3 experimental groups (n= 6 per group): 1) Normotensive rats (N), 2) Hemorrhagic shock rats (HS) and 3) Hemorrhagic shock rats treated with L-NAME (HS-L-NAME). Rats were hemorrhaged over 60 min to reach a mean arterial blood pressure of 40 mmHg. Rats were treated with 1 ml of 8 mg/Kg L-NAME intra-arterially after 60 min hemorrhagic shock. Resuscitation was performed in vivo by the reinfusion of the shed blood for 30 min to restore normo-tension. Arterial blood samples were collected from all groups at the end of the experimental period for measurement of tumor necrosis factor α (TNF-α). Biopsy samples were taken for light microscopy. Histological examination of hemorrhagic shocked untreated rats revealed structural damage. Less histological damage was observed in multiple organs in L-NAME- treated rats. L-NAME-treatment decreased the number of inflammatory cells and mitochondrial swollen in myocardial cells. Treatment with L-NAME decreased the inflammatory response to hemorrhagic shock by lowering the levels of TNF-α. L-NAME treatment reduced microscopic damage and injury in multiple organs and reduced the inflammatory response to hemorrhagic shock by inhibiting iNOS in a hemorrhagic shock model in rats.

Hemodynamic responses elicited by systemic injections of isotonic and hypertonic saline in hemorrhaged rats

PurposeThe objectives of this study were (i) to characterize the hemodynamic responses caused by controlled hemorrhage (HEM) in pentobarbital-anesthetized rats, and (ii) to determine the responses elicited by systemic bolus injections of isotonic saline (0.15M) or hypertonic saline (3M) given 5min after completion of HEM. ResultsControlled HEM (4.3±0.2ml/rat at 1.5ml/min) resulted in a pronounced and sustained fall in mean arterial blood pressure (MAP) to about 40mmHg. The fall in MAP was associated with a reduction in hindquarter vascular resistance (HQR) but no changes in renal (RR) or mesenteric (MR) vascular resistances. Systemic injections of isotonic saline (96–212μmol/kg i.v., in 250–550μl) did not produce immediate responses but promoted the recovery of MAP to levels below pre-HEM values. Systemic injections of hypertonic saline (750–3000μmol/kg, i.v., in 250–550μl) produced immediate and pronounced falls in MAP, RR, MR and especially HQR of 30–120s in duration. However, hypertonic saline prompted a full recovery of MAP, HQR and RR to pre-HEM levels and an increase in MR to levels above pre-HEM values. ConclusionsThis study demonstrates that (i) HEM induced a pronounced fall in MAP which likely involved a fall in cardiac output and HQR, (ii) isotonic saline did not fully normalize MAP, and (iii) hypertonic saline produced dramatic initial responses, and promoted normalization of MAP probably by restoring blood volume and cardiac output through sequestration of fluid from intracellular compartments.

Effect of Ulinastatin in reducing expression of HMGB1 in hemorrhagic shock rat lung with acute lung injury

Objective To observe the effect of Ulinastatin on the acute lung injury (ALI) and the expression of high mobility group box 1 protein (HMGB1) in hemorrhagic shock rat lung.Methods A total of 54 healthy male SD rats were randomly divided into the following 3 groups:normal control,normal saline (NS)+shock,Ulinastatin+shock.Rats were subjected to administration of NS or Ulinastatin before the 90 minshock,followed by execution respectively at 3h,6h and 12h to test the PaCO2,PaO2 and level of blood lactate,the rate of water content and the expression of HMGB1 of the lung were measured respectively by the wet/dry weight ratio method and western blot.Histopathologic changes were observed by hematoxylin-eosin staining.Results Increased PaCO2,lactate level,the rate of water content and the expression of HMGB1 were found,decreased PaO2 and massive inflammatory cell infiltration were observed in NS+shock group indicating ALI compared with those in normal control group.In Ulinastatin+shock group,these alterations were partially inhibited.Conclusion The high expression of HMGB1 and the inflammatory reaction in ALI rat induced by hemorrhagic shock can be attenuated by Ulinastatin,followed by lung function improvement. Key words: Hemorrhagic shock; Ulinastatin; HMGB1; Acute lung injury (ALI)

Small Doses of Arginine Vasopressin in Combination With Norepinephrine “Buy” Time for Definitive Treatment for Uncontrolled Hemorrhagic Shock in Rats

Implementation of fluid resuscitation and blood transfusion are greatly limited in prehospital or evacuation settings after severe trauma or war wounds. With uncontrolled hemorrhagic shock rats, we investigated if arginine vasopressin (AVP) in combination with norepinephrine (NE) is independent (or slightly dependent) of fluid resuscitation and can "buy" time for the subsequently definitive treatment of traumatic hemorrhagic shock in the present study. The results showed that AVP (0.4 U/kg) alone or with NE (3 μg/kg) with one-eighth and one-fourth volumes of total blood volume of lactated Ringer's infusion significantly increased and maintained the mean arterial pressure. Among all groups, 0.4 U/kg of AVP + NE (3 μg/kg) with one-eighth volume of lactated Ringer's infusion had the best effect: it significantly increased and maintained hemodynamics and prolonged the survival time. This early treatment strategy significantly improved the effects of subsequently definitive treatments (after bleeding controlled): it increased the subsequent survival, improved the hemodynamic parameters, improved the cardiac function, and increased the tissue blood flow and oxygen delivery. These results suggested that early application of small doses of AVP (0.4 U/kg) + NE before bleeding control can "buy" time for the definitive treatment of uncontrolled hemorrhagic shock, which may be an effective measure for the early treatment of traumatic hemorrhagic shock.

Effect of mesenteric lymph duct ligation on gene expression profiles of renal tissue in hemorrhagic shock rats with fluid resuscitation

Background: Acute kidney injury (AKI), a common pathological process following hemorrhagic shock, can lead to an internal milieu disorder, which is an important factor of multiple organ failure (MOF). It has been shown that the mesenteric lymph return plays a deleterious effect on MOF induced by hemorrhagic shock. In this study, we investigated the effects of mesenteric lymph duct ligation (MLDL) on gene expression profiles of renal tissue following hemorrhagic shock with fluid resuscitation. Methods: After establishment of hemorrhagic shock model and fluid resuscitation in rats of shock and shock ligation groups, the MLDL was performed in shock ligation group, and only threading under the mesenteric lymph duct in the shock group. Then, the fixed position renal tissue was taken out for homogenate in two groups at 3 h after resuscitation, the total mRNA was extracted, reversely transcribed into cDNAs and marked with Cy3 and Cy5. The cDNAs were subjected for microarray scanning with 12,028 cDNA probes; the differentially expressed genes between two groups were analyzed. Results: In the 5812 valid dates of rat genomes transcription, there were 34 known differentially expressed genes between the two groups, of which 11 genes were up-regulated whereas 23 genes were down-regulated by MLDL. These different expressed genes encoding protein function were mainly involved in signal transduction, transcription regulation, metabolism, transport, cell growth, cell cycle, cell adhesion, cell movement, cellular component, and biological process. Conclusions: The mechanism of MLDL alleviating the AKI aftershock might be associated with up- or down-regulation of the above gene expressions.

Quantitative gait analysis of long-term locomotion deficits in classical unilateral striatal intracerebral hemorrhage rat model

Gait analysis is a systematic collection of quantitative information on bodily movements during locomotion. Gait analysis has been employed clinically in stroke patients for their rehabilitation planning. In animal studies, gait analysis has been employed for the assessment of their locomotive disturbances in ischemic stroke, spinal cord injury and Parkinson's disease. The aims of the work reported here were to identify the gait parameters, collected from the computer-generated CatWalk System, that change after unilateral intracerebral hemorrhage (ICH) in the acute stage and long term up to 56 days post-ICH. The results showed that with the collagenase-induced unilateral striatal lesion, the rats displayed a significant contralateral decrease in print and maximum contact area and paw intensity, a diagonal increase in the stance duration of the left front and right hind paws, a significant decrease in the stride length of all four limbs, and foot pattern instability as reflected by the base of support, support on styles, and cadence. These deficits, including those in print area, stance and pressure, were demonstrated throughout the long-term period following ICH. The correlations between the gait parameters, lesion volume and asymmetrical forelimb use were also reported in this paper. This work has provided a systematic description on gait parameters in the classical striatal ICH model, which might become an essential assessment tool in future studies of pathophysiology and the development of novel treatments for experimental unilateral intracerebral hemorrhage with gait deficits.

Preservation of myocardial contractile function by aminoguanidine, a nitric oxide synthase inhibitors, in a rat model of hemorrhagic shock

Myocardial contractile dysfunction plays a major role in the outcome of trauma patients. Nitric oxide (NO) has been shown to increase following haemorrhagic shock. Peroxynitrite which is produced by the reaction of NO with reactive oxygen species leads to nitrosative stress mediated organ injury and myocardial contractile dysfunction. Aminoguanidine is a selective inhibitor of inducible nitric oxide synthase (iNOS). The aim of this study was to determine the protective effects of inhibiting the production of NO using aminoguanidine (AG) on myocardial contractility, following hemorrhagic shock and resuscitation in rats. Male Sprague-Dawley rats were assigned to 3 experimental groups (n = 6 per group):1) Normotensive rats (N), 2) Hemorrhagic shock rats (HS), and 3) Hemorrhagic shock rats treated with AG 60 mg/kg AG intra-arterially (HS-AG). Rats were hemorrhaged over 60 minutes to reach a mean arterial blood pressure of 40 mmHg. Rats were treated with 1 ml of 60 mg/Kg AG intra-arterially after 60 minutes haemorrhagic shock,. Resuscitation was performed in vivo by the reinfusion of the shed blood for 30 minutes to restore normo-tension. Hearts were harvested and ex vivo perfused in the Langendorff System and myocardial function was determined by measuring the left ventricular end diastolic pressure (LVEDP) and left ventricular systolic pressure (LVSP). Left ventricular generated pressure (LVGP) and + dP/dt max was calculated. Hemorrhagic shock rats treated with AG exhibited a significant increase in left ventricular generated pressure LVGP (137.1 ± 9.4 mmHg) and + dP/dtmax (589.6 ± 110.7 mmHg/sec) compared with the untreated group (44.43 ± 20.18 mmHg, 289.8 ± 25.0 mmHg/sec). Treatment with AG protects the myocardium from post-resuscitation myocardial dysfunction.

Pharmacologic Suppression of Inflammation by a Diphenyldifluoroketone, EF24, in a Rat Model of Fixed-Volume Hemorrhage Improves Survival

An exaggerated release of proinflammatory cytokines and accompanying inflammation contributes to the development of multiple organ failure after hemorrhagic shock. Here, we tested the nuclear factor (NF) κ-light-chain-enhancer of activated B cell (NF-κB)-mediated transcriptional control of inflammatory pathways as a target in the management of hemorrhage-induced inflammation. We performed a study in a rat model of fixed-volume hemorrhage to investigate the anti-inflammatory effects of the diphenyldifluoroketone EF24 [3,5-bis(2-fluorobenzylidene)piperidin-4-one], an NF-κB inhibitor, in lung tissue. EF24 treatment (0.4 mg/kg) significantly prevented the upregulation of inflammatory biomarkers in rats subjected to 50% hemorrhage and preserved the pulmonary histology in hemorrhaged rats. The lung tissue from treated rats showed marked suppression of the hemorrhage-mediated induction of Toll-like receptor 4, phospho-p65 NF-κB, inducible nitric-oxide synthase, heme oxygenase-1, and cyclooxygenase-2 (COX-2). The hemorrhage-induced COX-2 activity was also significantly inhibited by the EF24 treatment. At the same time, EF24 induced nuclear factor (erythroid-derived 2)-like 2-mediated protective mechanisms against oxidative stress. EF24 also reduced hemorrhage-induced lung myeloperoxidase activity. The plasma levels of proinflammatory tumor necrosis factor-α, interleukin (IL)-6, IL-1α, and IL-1β were lower in EF24-treated rats than in untreated rats. Moreover, there was a significant reduction in the pulmonary expression of high-mobility group B1 protein. These biochemical effects were accompanied by a significant improvement in the survival of rats administered with EF24 as compared with the rats receiving vehicle control (P < 0.05). Overall, the results suggest that EF24 attenuates hemorrhage-induced inflammation and could serve as a salutary anti-inflammatory agent in resuscitation strategies.

Efficacy of centhaquin as a small volume resuscitative agent in severely hemorrhaged rats

Centhaquin has been reported to be an effective resuscitative agent. The present study was carried out to determine resuscitative effect of centhaquin when administered using a small volume of 3% hypertonic saline (HS) to hemorrhaged rats. Sprague-Dawley rats were anesthetized with urethane, and a pressure catheter SPR-320 was placed in the left femoral artery; another pressure-volume catheter SPR-869 was placed into the left ventricle. Hemorrhage was induced by withdrawing blood and mean arterial pressure (MAP) was maintained at 35 mm Hg for 30 minutes after which resuscitation was performed. Animals were divided in 2 groups: group A received HS and group B received centhaquin (0.05 mg/kg) dissolved in HS. The time by which MAP fell back to 35 mm Hg was observed at that time all animals were administered fresh blood. It was found that centhaquin significantly reduced blood lactate and improved cardiac output and MAP of hemorrhaged rats compared with HS. The time by which MAP fell back to 35 mm Hg in rats treated with HS was 55 ± 6 minutes, whereas it was 161 ± 14 minutes in centhaquin treated rats. Survival time following administration of fresh blood was 79 ± 7 minutes in vehicle-treated group, whereas it was 105 ± 9 minutes in centhaquin-treated rats. The total time of survival of rats treated with HS or centhaquin was 134 ± 12 minutes and 266 ± 16 minutes, respectively. Centhaquin, in small volume, maintained MAP of hemorrhaged rats for a considerable long time and improved the survival time.

Role of RhoA in Regulating the Pump Function of Isolated Lymphatics From Hemorrhagic Shock Rats

The aim of this present study was to examine changes in RhoA protein levels and the role in RhoA in lymphatic contractility and reactivity after hemorrhagic shock. Levels of RhoA and phospho-RhoA in lymphatic tissue isolated from hemorrhagic shock rats were measured, and the contractility and reactivity to substance P of lymphatics isolated from control rats and rats subjected to shock 0.5 and 2 h were determined with an isolated lymphatic perfusion system at a transmural pressure of 3 cmH2O. At the same time, lymphatics isolated from rats subjected to shock 0.5 and 2 h were incubated with agonists and antagonists of RhoA/Rho kinase signaling. Contractile frequency, end-diastolic and end-systolic diameter, and passive diameter were recorded and used to calculate lymphatic tonic index, contractile amplitude, and fractional pump flow. After stimulation with a gradient of substance P, the differences between the preadministration and postadministration values of contractile frequency, contractile amplitude, tonic index, and fractional pump flow were calculated to further assess lymphatic reactivity. RhoA protein levels were significantly increased at 0.5 h after shock but decreased at 2 and 3 h after shock; p-Rho levels were initially increased after shock and subsequently decreased. The contractility and reactivity of 0.5-h-shocked lymphatics were significantly reduced by the RhoA antagonist C3 transferase and the Rho kinase antagonist Y-27632. The RhoA agonist U-46619 increased the contractility and reactivity of 2-h-shocked lymphatics, whereas Y-27632 suppressed the effect of U-46619. Okadaic acid, an inhibitor of myosin light-chain phosphatase, had no effect on the contractility of 2-h-shocked lymphatics, but improved lymphatic reactivity. These results suggest that RhoA is involved in the modulation of lymphatic pump function during hemorrhagic shock and that its effects may be mediated by Rho kinase and MLCP.

Role of protein kinase G on the post-shock mesenteric lymph blockage ameliorating vascular calcium sensitivity

To investigate the role of protein kinase G (PKG) in blocking post-shock mesenteric lymph (PSML) return ameliorating the calcium sensitivity in hemorrhagic shock rats. Male Wistar rats were randomly divided into sham, shock, shock+ligation (shock plus mesenteric lymph duct ligation (MLDL)), shock+drainage (shock plus PSML drainage) groups. After shock (hypotension 40 mm Hg) for three hours or corresponding times, the superior mesenteric artery (SMA) was taken out for detecting the PKG and phospho PKG (p-PKG) contents, and the vascular rings of SMA were prepared for assaying the calcium sensitivity using an isolated organ perfusion system. The PKG and p-PKG contents of SMA in shock group were significantly increased than that of sham group, and MLDL or PSML drainage reducing the levels of PKG and p-PKG. Meanwhile, the vascular calcium sensitivity in shock group was significantly lower than that of sham group, MLDL or PSML drainage enhanced the calcium sensitivity. After incubating with PKG regulators in shock+ligation and shock+drainage groups, the PKG agonist 8Br-cGMP reduced the contractility of vascular rings to gradient calcium ions and Emax and the PKG inhibitor agonist KT5823 elevated the calcium sensitivity significantly. Protein kinase G plays an important role in post-shock mesenteric lymph blockage improving vascular calcium sensitivity.

High-lipid enteral nutrition could partially mitigate inflammation but not lung injury in hemorrhagic shock rats

BackgroundLoss of gut barrier function is crucial in mediating lung injury induced by hemorrhagic shock/resuscitation (HS). High-lipid enteral nutrition (HL) can preserve gut barrier function. We hypothesized that HL could also mitigate HS-induced lung injury. Materials and methodsForty-eight adult male rats were randomly assigned to one of four experimental groups: HS; HS-HL; Sham; Sham-HL. HS was induced by blood drawing and mean blood pressure was maintained at 40–45 mmHg for 120 min followed by resuscitation with re-infusion of exsanguinated blood/saline mixtures. HL gavage was performed at 45 min before blood drawing and at the end of resuscitation. ResultsIntestinal permeability of the HS group was significantly higher than that of the Sham group (P < 0.001). Pulmonary concentrations of malondialdehyde (lipid peroxidation) and inflammatory molecules, including prostaglandin E2, tumor necrosis factor-α, interleukin-6, and macrophage inflammatory protein-2, of the HS group were significantly higher than those of the Sham group. Histologic analyses, including histopathology, wet/dry weight ratio, and neutrophil infiltration revealed moderate lung injury in the HS group. In contrast, intestinal permeability (P < 0.001) and pulmonary concentrations of tumor necrosis factor-α and macrophage inflammatory protein-2 (P = 0.021 and 0.01) of the HS-HL group were significantly lower than those of the HS group. However, pulmonary concentrations of malondialdehyde, prostaglandin E2, and interleukin-6 of the HS-HL and HS groups were comparable. Moreover, histologic analyses also revealed moderate lung injury in the HS-HL group. ConclusionsHigh-lipid enteral nutrition significantly mitigated gut barrier loss and partially mitigated lung inflammation but not oxidation and lung injury in hemorrhagic shock/resuscitation rats.

Mitogen-activated protein kinases regulate vascular reactivity after hemorrhagic shock through myosin light chain phosphorylation pathway

Vascular hyporeactivity played an important role in many critical illness including shock or sepsis, but the mechanisms are incompletely understood. The objective of the present study was to investigate the roles of major mitogen-activated protein kinases (MAPKs extracellular signal-regulated kinase [ERK], p38 MAPK, and jun NH2-terminal kinase [JNK]) on vascular reactivity and the mechanisms. With superior mesenteric arteries from hemorrhagic shock rats, the role of p38 MAPK, ERK, and JNK in the regulation of vascular reactivity following shock and their relationship to myosin light chain (MLC20) phosphorylation-dependent pathway was observed. ERK, p38 MAPK, and JNK activities in superior mesenteric arteries were increased at early shock and decreased at late shock. Stimulation of MAPKs with angiotensin II (AngII) increased the vascular reactivity, calcium sensitivity, and MLC20 phosphorylation. The increasing effect of AngII on vascular reactivity was antagonized by ERK, p38 MAPK, and JNK inhibitors, while the effect of AngII on calcium sensitivity was only blocked by ERK and p38 MAPK inhibitor, but not by JNK inhibitor. AngII increased the activity of protein kinase C-dependent phosphatase inhibitor of 17-kD (CPI17), integrin-linked kinase (ILK), and zipper-interacting protein kinase (ZIPK), The effect of AngII on CPI17 was blocked by ERK and p38 MAPK inhibitor, while the effect of AngII on ILK and ZIPK was only blocked by ERK inhibitor. MAPKs participated in the regulation of vascular reactivity during shock. ERK and p38 MAPK is mainly through ILK, ZIPK, and CPI17-mediated MLC20 phosphorylation-dependent pathway, while JNK may be involved in the regulation of vascular reactivity by other mechanisms.

Resuscitation With Aged Blood Exacerbates Liver Injury in a Hemorrhagic Rat Model

Resuscitation With Aged Blood Exacerbates Liver Injury in a Hemorrhagic Rat Model