Hypovolemic models of acute tubular necrosis in the rat kidney

Establishment of an experimental mouse model of trauma-hemorrhagic shock

This study established an experimental mouse model of trauma-hemorrhagic shock (THS). THS-induced mice (C57BL/6J, n=33) were subjected to femoral fracture, ischemia for 90 min, and resuscitation for 15 min. The sham-operated mice (C57BL/6J, n=33) underwent the same anesthetic and surgical procedures, but neither trauma-hemorrhage nor fluid resuscitation were performed. Mean arterial pressure (MAP) and microvascular tissue perfusion over the small intestine, liver, and left kidney were longitudinally measured in all mice. Blood was collected for analysis at baseline and 3, 6, 12, and 24 h post resuscitation, and the small intestine, liver, and left kidney were resected for hematoxylin and eosin staining 24 h post resuscitation. Compared with the sham group, MAP and microvascular tissue perfusion over the small intestine, liver, and left kidney were all significantly reduced in the THS group at the end of hemorrhage. Following resuscitation, no significant differences were observed between the groups. THS induction was associated with significantly increased plasma concentrations of Cr, AST, CPK, IL-6, IL-10, and TNF-α from the baseline values by two- to three-fold after the hemorrhage phase, and THS-induced mice demonstrated significantly increased histological injury scores. The rapid drop in MAP and microvascular tissue perfusion observed following THS induction, and the gradual recovery post resuscitation, reflects the successful establishment of a THS experimental mouse model.

Prolonged Blood Storage Does Not Effect Survival in an Animal Model of Hemorrhagic Shock

SUMMARY: BACKGROUND: Red blood cell (RBC) transfusion in hemorrhagic shock is life saving. However, several clinical trials have shown that blood transfusion in the critically ill patient might be associated with adverse outcomes. Furthermore, an association between prolonged blood storage and adverse effects of RBC transfusion has been postulated. The aim of this study is to examine the effect of blood storage time on resuscitation outcome, in an animal model of hemorrhagic shock. METHODS: 20 Wistar rats were phlebotomized in order to induce reversible hemorrhagic shock. Half of them were resuscitated with blood stored for a short period of time (4 days), and the other ones were resuscitated with blood stored for a prolonged time (14 days). Blood samples for hemoglobin, pH, lactate, bicarbonate and creatinine were drawn prior to the induction of shock and 24 h after resuscitation. Five days after resuscitation the animals were sacrificed, and liver, lung and kidney histology was examined. RESULTS: At 24 h after bleeding, the hemoglobin levels decreased by 3.2 and 1.7 g/dl, the pH decreased by 0.008 and 0.001, while the lactate levels increased by 1.6 and 2.7 mg/dl in the fresh and old blood resuscitation groups, respectively, with no significant difference between the groups. A trend toward more severe renal damage occurred in the old compared to the fresh blood resuscitation group (p = 0.089). CONCLUSION: The results of the present study show that in this animal model of hemorrhagic shock the duration of storage of RBCs used for transfusion did not affect the outcome of resuscitation.

Inhibition of interleukin-6-transsignaling via gp130-Fc in hemorrhagic shock and sepsis

BACKGROUND

Immune function after hemorrhagic shock and subsequent sepsis is characterized by an early proinflammatory burst of IL-6, and high IL-6 levels have been linked to high mortality after trauma and in sepsis. Trans-signaling is defined as the activation of cells that do not express the membrane bound IL-6 receptor by the complex of IL-6 and the soluble IL-6 receptor (sIL-6R). Gp130-Fc is able to bind the IL-6/sIL-6R complex, and beneficial effects of IL-6 blockade in chronic inflammatory diseases have been shown. The first aim of this study was to investigate the potential effect of a gp130 blockade via the gp130-Fc antibody causing impairment of IL-6 signaling. The second aim was to find out what role the IL-6/sIL-6R complex can play in the context of hemorrhagic shock and subsequent sepsis as an acute inflammatory disease.

MATERIAL AND METHODS

Male CBA/J mice were subjected to hemorrhagic shock (35+/-5 mmHg for 90min and fluid resuscitation) or sham operation. At resuscitation each animal received either 0.5mg gp130-Fc or placebo (PL) i.p. At 48 h after resuscitation, both splenocytes and peritoneal macrophages (pMphi) were harvested or polymicrobial sepsis was induced by cecal ligation and puncture. Survival over 10 d was determined. Release of IL-6, TNF-alpha, and IL-10 of pMphi and release of IL-2, IL-10, and IFN-gamma of splenocytes was assessed by ELISA. Proliferation of splenocytes and their morphologic damage were determined.

RESULTS

Binding of the IL-6/sIL-6R complex by gp130-Fc led to significant lower IL-6 levels compared with placebo treated animals. Placebo treated males showed depressed proinflammatory immune response (IL-2, IL-6) after hemorrhagic shock. While splenocyte proliferation was significantly reduced directly after hemorrhagic shock and restored after 48 h by gp130-Fc, pMphi cytokine release was not influenced. Finally, survival appeared to be unaffected.

CONCLUSION

Transsignaling does not seem to play a pivotal role in the development of the immune dysfunction and mortality in our model of hemorrhage and subsequent sepsis.

Influence of sex and age on morphological organ damage after hemorrhagic shock

Immune function after hemorrhagic shock (shock) and subsequent sepsis is proofed to be sex- and age-related, showing an enhanced immune function and better survival of young females and a deteriorating immune response in advanced age. However, it remains unclear if the observed sex- and age-related effects observed on the immune function mirror the histomorphological changes of the affected organs. To scrutinize a possible association, male and female CBA/J mice (young, 2-3 months; aged 18-19 months) were subjected to shock (35 + 5 mmHg for 90 min and fluid resuscitation) or sham operation. At 48 h after shock, histological specimen at definite sites were harvested (lung, small bowel, liver, and kidney) and immediately stored in 10% formalin. After paraffin embedding, hematoxylin-eosin stain and immunohistochemical stains (vascular cell adhesion molecule 1 [VCAM-1], cluster of differentiation 44 [CD44], signal transducers and activators of transcription 3 [STAT-3]) were performed. In both sexes, aged animals developed significantly increased (P < 0.05) tissue damage in all analyzed organs compared with young mice. Sex differences were noticed in the lungs of young mice, showing a significantly (P < 0.05) lower organ damage score in female animals. Sex-related differences were found for VCAM-1 and cluster of differentiation 44 expression, whereas age-related changes were observed for STAT-3. These results demonstrate that the severity of tissue damage caused by hemorrhagic shock is influenced by sex- and age-related effects. Variances in the VCAM-1 and STAT-3 expression suggest that improved immune function in female and young subjects may be responsible for less shock-induced tissue damage.