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A new method for reproduction of metastatic involvement of the liver in outbred albino rats is proposed. The use of the method rules out the effects of stress factors (surgical intervention, total anesthesia) on malignant tumor metastasizing, making it maximally similar to the natural process. The method allows visual evaluation of the time course of the primary tumor node growth. The metastatic involvement of the liver develops only by the most significant route, hematogenic. The method can be used for the development of experimental therapy for this condition. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: The purpose of the study was to determine the compensatory function of the remnant liver as a blood reservoir after 70% hepatectomy in rats to counteract hemorrhagic shock and reperfusion. Methods and materials: One hour of hemorrhagic shock followed by 1 hour of resuscitation induced in normal rats (group I) was compared with animals that had undergone 70% hepatectomy at postoperative day 3 (group II) and day 7 (group III). We compared the total blood loss, the blood pressure before hemorrhagic shock, hemoglobin, hemotocrit, and mortality. Liver function such as aspartate transferase (AST), alanine transferase, and lactate dehydrogenase (LDH) were also compared among groups by one-way analysis of variance with post hoc correction. A P value less than .05 was regarded as significant. Results: The results showed a lower volume of drawn blood induced hemorrhagic shock in group II compared with group I or group III hosts. The blood loss was 15.6 ± 1.0, 5.68 ± 2.5, and 13.2 ± 1.6 mL for groups I, II, and III, respectively. The mortality due to hemorrhagic shock was significantly higher in group II compared with group I or group III. Liver function tests showed that the AST and LDH were significantly higher after resuscitation in group II. Conclusion: In the early postoperative period (day 3) after 70% hepatectomy, rats were more vulnerable to a high mortality after hemorrhagic shock compared with hosts in the late postoperative period (day 7). Significantly higher AST and LDH in group II indicated that the remnant liver was more injured after hemorrhagic shock in the early postoperative period. [Copyright &y& Elsevier]

Abstract: Objective: The aims of the study were to determine the effects of denervation on the function of the liver transplantation as a blood reservoir and to define its vulnerability to ischemic-reperfusion (I/R) injury after hemorrhagic shock. Materials and methods: Hemorrhagic shock with a mean arterial blood pressure (MAP) of 40 to 50 mm Hg was induced by withdrawing blood at a rate of approximately 1 mL/min among 10 posttransplant denervated rats and 10 sham rats for 1 hour. The rats were then resuscitated by retransfusing the drawn blood with sacrifice under deep anesthesia at 1 hour after resuscitation. The total amount of blood required to achieve hemorrhagic shock was compared between groups as well as the vulnerability and reactions of the posttransplant denervated liver to I/R injury after hemorrhagic shock as assessed by gene expressions of c-jun, c-fos, tumor necrosis factor (TNF)-alpha, interleukin (IL)6, IL-10, and heat-shock protein 70 (HSP70). Results: The volume of blood that had to be drawn to reach a MAP of 40 to 50 mm Hg was not significantly different between the groups. One hour of hemorrhagic shock followed by resuscitation resulted in significant increases in the genes expression of c-fos, TNF-alpha, IL-6, IL-10, and HSP70 in comparison to the control values, but no difference was observed between experimental and sham groups. Conclusion: We suggest that the function of the liver as a blood reservoir and the gene expressions of c-fos and pro- and anti-inflammatory cytokines, as well as the protective protein HSP70 in response to I/R injury, were not altered by liver transplantation. [Copyright &y& Elsevier]

Discusses a study which determined whether heme oxygenase-1 (HO-1) induction restores cyclic adenosine monophosphate-dependent lung epithelial fluid transport following severe hemorrhage in rats. Role of hemorrhagic shock in the decrease of alveolar epithelial fluid transport; Restoration of normal alveolar epithelial fluid transport by HO-1; Role of HO-1 in the attenuation of nitric oxide release by alveolar macrophages.

The author comments on the study by Shellington et al which investigated the effectiveness of polynitroxylated pegylated hemoglobin (PNP-Hb) for fluid resuscitation of traumatic patients with hemorrhagic shock in rats. He stresses that the strength of the study includes the use of the combined in vitro and in vivo approach, experimental technique in vivo, the experimental protocol and the use of relevant control compounds. He also cites the weak points of the study including the lack of insight into the neuroprotective mechanisms of PNP-Hb.

The author discusses a laboratory study on resuscitation from uncontrolled hemorrhagic shock in rats published within the issue. The study demonstrated that fluid administration can be harmful during early resuscitation. The author cites the questions raised by the study findings. He also ponders on the clinical implications of the study findings.

Previous studies from our laboratory demonstrated a positive correlation between hemorrhagic shock (HS)-induced vascular hyperpermeability and endothelial cell reactive oxygen species (ROS) generation. We hypothesized that curcumin a known antioxidant obtained from turmeric (Curcuma longa), would attenuate vascular hyperpermeability following HS. The objective of this study was to determine if curcumin prevents ROS production and vascular hyperpermeability following HS in rat mesentric vasculature in vivo. In rats, HS was induced by withdrawing blood to reduce the MAP to 40 mmHg for 60 minutes followed by resuscitation to 90 mmHg with the shed blood and saline. To study vascular permeability, the rats were injected intravenously with FITC-albumin (50 mg/kg) and the FITC-albumin flux was measured by determining the changes in integrated optical intensity obtained intra and extra vascularly using intravital microscopy. ROS production was determined by using the fluorescent dye dihydrorhodamine 123, that was superfused on the exposed mesenteric vasculature. The results showed that, HS induced hyperpermeability in rat mesenteric vasculature. Curcumin pre-treatment (20 µM) attenuated HS-induced hyperpermeability (p < 0.05). HS was followed by a significant rise in intracellular ROS generation. Hemorrhagic shock-induced ROS rise was inhibited by curcumin (20 µM; p < 0.05). Together, these findings show that curcumin is effective in maintaining endothelial cell barrier integrity following hemorrhagic shock. The protective effects of curcumin may be mediated through its antioxidant properties. [ABSTRACT FROM AUTHOR]

Uncontrolled hemorrhage, resulting from traumatic injuries, continues to be the leading cause of death in civilian and military environments. Hemorrhagic deaths usually occur within the first 6 hours of admission to hospital; therefore, early prehospital identification of patients who are at risk for developing shock may improve survival. The aims of the current study were: 1. To establish and characterize a unique model of uncontrolled internal hemorrhage induced by massive renal injury (MRI), of different degrees (20-35% unilateral nephrectomy) in rats, 2. To identify early biomarkers those best predict the outcome of severe internal hemorrhage. For this purpose, male Sprague Dawley rats were anesthetized and cannulas were inserted into the trachea and carotid artery. After abdominal laparotomy, the lower pole of the kidney was excised. During 120 minutes, hematocrit, pO2, pCO2, base excess, potassium, lactate and glucose were measured from blood samples, and mean arterial pressure (MAP) was measured through arterial tracing. After 120 minutes, blood loss was determined. Statistical prediction models of mortality and amount of blood loss were performed. In this model, the lowest blood loss and mortality rate were observed in the group with 20% nephrectomy. Escalation of the extent of nephrectomy to 25% and 30% significantly increased blood loss and mortality rate. Two phases of hemodynamic and biochemical response to MRI were noticed: the primary phase, occurring during the first 15 minutes after injury, and the secondary phase, beginning 30 minutes after the induction of bleeding. A Significant correlation between early blood loss and mean arterial pressure (MAP) decrements and survival were noted. Our data also indicate that prediction of outcome was attainable in the very early stages of blood loss, over the first 15 minutes after the injury, and that blood loss and MAP were the strongest predictors of mortality. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Hemorrhage alone without concomitant trauma often results in a hypercoagulable state that makes it difficult to prevent clotting within the blood withdrawal catheters. Although systemic administration of heparin can ameliorate this problem, heparin use has many additional actions that may confound interpretation of the hemorrhage experiments. The problem can be resolved by the use of a dual lumen catheter that anticoagulates only the blood within the withdrawal circuit. We describe the design of such a catheter and evaluate its function in studies of hemorrhagic shock in rats. Materials and methods: Construction directions are provided for the dual lumen catheter along with a commercial source. The catheters were connected to computer controllable infusion syringes. Either citrate or heparin was used for regional extracorporeal anticoagulation. Rats were anesthetized and hemorrhaged to 40mmHg for more than 15min through the use of a computer program written in Labview. Ionized calcium measurements were obtained pre- and posthemorrhage. Results: The catheters remained patent throughout the experiments. There was no significant difference in the ionized calcium whether citrate or heparin was used for extracorporeal anticoagulation. Conclusion: The dual lumen catheters are suitable for the study of hemorrhagic shock in rats without the need for systemic anticoagulation. The catheters can be used with computer-controlled hemorrhage procedures. [Copyright &y& Elsevier]

Background: Hemorrhagic shock (HS) followed by resuscitation can result in production of several inflammatory mediators, such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), leading to multiple organ dysfunction. Melatonin can attenuate organ damage with its anti-inflammation effects. The present study was designed to investigate the effects of melatonin on the physiopathology and cytokine levels after HS in rats. Methods: HS was induced in rats by withdrawing 40% of the total blood volume (6mL/100 gm body weight) from a femoral artery catheter, immediately followed by intravenous injection of 10mg/kg melatonin. Mean arterial pressure and heart rate were monitored continuously for 48h after the start of blood withdrawal. Biochemical parameters, including levels of hemoglobulin, glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), blood urea nitrogen (BUN), creatinine (Cre), lactic dehydrogenase (LDH), creatine phosphokinase (CPK), and lactate, were determined 30min before and 0, 1, 3, 6, 12, 24, and 48h after induction of HS while an equal volume of normal saline was replaced as fluid resuscitation. Cytokine levels including TNF-α and IL-6 in the serum were measured at 1, 24, and 48h after HS. The kidney, liver, lung, and small intestine were removed for pathology assessment at 48h after HS. Results: HS significantly increased the heart rate, blood GOT, GPT, BUN, Cre, LDH, CPK, lactate, TNF-α, and IL-6 levels, and decreased hemoglobulin and mean arterial pressure in rats. Treatment with melatonin preserved the mean arterial pressure, decreased tachycardia, and markers of organ injury, and suppressed the release of TNF-α and IL-6, with no change in hemoglobulin after HS in rats. Conclusion: Treatment with melatonin suppresses the release of serum TNF-α and IL-6, and decreases the levels of markers of organ injury associated with HS, thus ameliorating HS-induced organ damage in rats. [Copyright &y& Elsevier]

Background: Plasma factor XIII (FXIII) is responsible for stabilization of fibrin clot at the final stage of blood coagulation. Since FXIII has also been shown to modulate inflammation, endothelial permeability, as well as diminish multiple organ dysfunction (MOD) after gut ischemia-reperfusion injury, we hypothesized that FXIII would reduce MOD caused by trauma-hemorrhagic shock (THS). Materials and methods: Rats were subjected to a 90 min THS or trauma sham shock (TSS) and treated with either recombinant human FXIII A2 subunit (rFXIII) or placebo immediately after resuscitation with shed blood or at the end of the TSS period. Lung permeability, lung and gut myeloperoxidase (MPO) activity, gut histology, neutrophil respiratory burst, microvascular blood flow in the liver and muscles, and cytokine levels were measured 3 h after the THS or TSS. FXIII levels were measured before THS or TSS and after the 3-h post-shock period. Results: THS‑induced lung permeability as well as lung and gut MPO activity was significantly lower in rFXIII-treated than in placebo-treated animals. Similarly, rFXIII-treated rats had lower neutrophil respiratory burst activity and less ileal mucosal injury. rFXIII-treated rats also had a higher liver microvascular blood flow compared with the placebo group. Cytokine response was more favorable in rFXIII-treated animals. Trauma-hemorrhagic shock did not cause a drop in FXIII activity during the study period. Conclusions: Administration of rFXIII diminishes THS-induced MOD in rats, presumably by preservation of the gut barrier function, limitation of polymorphonuclear leukocyte (PMN) activation, and modulation of the cytokine response. [ABSTRACT FROM AUTHOR]

Background. Hypoxia resultant from haemorrhagic shock is the primary cause of kidney damage. Application of normobaric hyperoxia therapy (NHT) is an acceptable treatment for acute haemorrhagic shock. We investigated the effect of NHT on amelioration of haemorrhagic shock-induced rat renal failure. Methods. Twenty-four Sprague-Dawley rats were subjected to gradual blood withdrawal/reperfusion, followed by 12-h, 24-h or 48-h NHT. Verification/monitoring of intrarenal hypoxia was performed using Hypoxyprobe-TM-1. Subsequently, cystatin C, urea and creatinine were assessed in serum by a Hitachi autoanalyser, and NO, 3-nitro-tyrosine, STAT-8-isoprostane and NF-kB in renal medullae and cortices by specific ELISAs. Results. In rats subjected to haemorrhagic shock, 12- to 48-h NHT significantly reduced intrarenal Hypoxyprobe-TM-1 stained areas and attenuated augmentation of urea, creatinine and cystatin C. Haemorrhagic shock resulted in a 10-fold drop of intrarenal NO availability. 12-h and 24-h, but not 48-h, NHT significantly increased cortical/medullar NO synthesis, the latter, however, not approaching the pre-shock values. Significant shock-induced accumulation of STAT-8-isoprostane and 3-nitro-tyrosine was further exacerbated by NHT. Haemorrhagic shock activated NF-kB in ischaemic tissues, which was not attenuated by NHT. Conclusions. (1) 12- to 48-h NHT decreased intrarenal hypoxia signs and ameliorated deterioration of renal functions in a rat model of haemorrhagic shock-induced renal failure. (2) 12- to 24 h NHT improved bioavailability of NO in cortices/medullae of kidneys recuperating from haemorrhagic shock. (3) If any anti-inflammatory activities were stimulated by NHT, they would not be mediated via the NF-kB pathway. (4) Despite NHT-associated elevation of reactive oxygen species (ROS), early oxygen supply proved mandatory for effective recuperation of ischaemic kidney from detrimental consequences of haemorrhagic shock. [ABSTRACT FROM AUTHOR]

Acute blood loss triggers heightened vasoconstriction which contributes to maintenance of the blood pressure. Hemorrhage also induces shock proteins, including heme oxygenase (HO)-1. HO metabolizes heme to form carbon monoxide (CO), which inhibits nitric oxide synthase to promote endothelial dysfunction. This study examines the hypothesis that hemorrhage induces HO-1, to enhance CO production and promote endothelial dysfunction which contributes to the restoration of blood pressure. Male Sprague-Dawley rats (300-350g) with chronic femoral arterial catheters were subjected to a 45% hemorrhage (shock). Hemorrhage produced vasodepression from 117±2 mmHg to 78±6 mmHg in 1 hour. At 36hrs, vascular HO-1 was induced (shock: 2.7±0.3 vs unbled: 1.1±0.2 ng/mg Pr), which was accompanied by a 25% increase in expired CO and restoration of arterial pressures to 106±2 mmHg. First order gracilis muscle arterioles, isolated from each group, were mounted in a microvessel chamber, superfused with oxygenated Krebs buffer and exposed to constant midpoint, but altered endpoint pressures to establish graded levels of luminal flow (0-50µL/min). Flow-induced dilation was abolished in shock arterioles (Δmax 0±0µm vs Δmax18±1µm, shock vs unbled; P<0.05). Acute pretreatment with an inhibitor of HO, chromium mesoporphyrin (15µmol/L) restored flow-induced dilation to control levels (Δmax 30±1µm). These data show that hemorrhagic shock can induce HO-1 to increase CO formation and promote endothelial dysfunction. Accordingly it suggests that shock induced increases in CO formation may contribute to the restoration of blood pressure via its well established ability to inhibit nitric oxide synthase. [ABSTRACT FROM AUTHOR]

WHPC extends the survival of mice exposed to lethal environmental hypoxia by preserving structural and functional integrity of key organs. We now examined whether WHPC would also prolong survival in response to hemorrhagic shock. Conscious male rats were subjected to bleeding of 60% of their estimated blood volume (∼37.2 ml/kg) over 30 min. We found that naïve rats died 76+9 min after the completion of bleeding (n=15) and this process was associated with progressively increasing metabolic acidosis and cell/organ injury. In contrast, more than 80% of rats treated with WHPC (6 cycles of 8% O2x10-min/21% O2x10-min) 2 h before bleeding survived >6 h without fluid resuscitation (n=14, p<0.001) and displayed significantly reduced acidosis and cell/organ injury. Although it decreased drastically following bleeding in all rats, Oz consumption in those treated with WHPC was significantly higher, suggesting better tissue perfusion in these animals. Furthermore, surviving animals appeared to be recovering from the initial impact of massive blood loss, with accelerated compensation and sustained maintenance of key variables above critical levels (mean arterial pressure >60 mmHg, blood base excess >-6 mmol/L, and plasma lactate <5 mmol/L). WHPC treatment 8 h before bleeding was associated with similar beneficial effects. We conclude that WHPC provides a robust protective mechanism against acute hemorrhagic shock. [ABSTRACT FROM AUTHOR]

Microvascular observations and measurements of the oxygen partial pressure (PO2) distribution are essential to understand tissue oxygenation. Longitudinal PO2 gradients have been reported previously, but few attempts have been made to investigate factors that can alter such a gradient. Despite its importance in hemorrhagic shock, the mesenteric microvascular PO2 distribution has never been evaluated during HH. We tested the hypothesis that the diverse hemodynamic responses of arterioles to HH would lead to changes in longitudinal PO2 gradients. The mesenteric microcirculation of anesthetized rats was studied under normovolemia (baseline) and during HH (mean arterial pressure = 50 mmHg). Diameter and blood flow of arterioles and venules of different orders were studied using intravital videomicroscopy. PO2 was determined using the phosphorescence quenching technique. During HH, blood flow was uniformly reduced in arterioles and venules, while PO2 showed a wider distribution. In arterioles, the small longitudinal PO2 gradient recorded during baseline was enhanced during HH. Two groups of vessels were observed with regard to PO2: large vessels showed PO2 levels similar to or above baseline, while small vessels showed reduced PO2. Changes in blood flow did not explain this variability, since the reduction in flow was similar for all vessels, irrespective of vessel order or type. [ABSTRACT FROM AUTHOR]

Hemorrhagic shock reflects low tissue perfusion that is inadequate to maintain normal metabolic functions. Often associated with this condition are impairments in cellular oxygen utilization. Rats bred for high (HCR) vs low (LCR) aerobic running capacity have greater O2 uptake and improved cardiovascular function (Gonzalez et al., J Appl Physiol 101: 1288, 2006). Hence, it was hypothesized that HCR would be more tolerant to global ischemia than LCR. To address this hypothesis, survival time to a severe controlled hemorrhage was measured. Male rats (generation 12) were catheterized and, ∼ 24 hours later, 55% of the calculated blood volume was removed during a 26 min period from conscious unrestrained animals. Rats were observed for 6 hr or until death. Contrary to our hypothesis, survival time in HCR (173 ± 55 min; n=8) did not differ (P = 0.24) from that in LCR (254 ± 52 min; n=8). Similarly, there were no differences between strains in blood pH, lactate, and base deficit values pre or post-hemorrhage. Since oxygen uptake and cardiac function are different in these rat strains, these results suggest that other mechanisms must play a more dominant role in determining survival time to hemorrhage. [ABSTRACT FROM AUTHOR]