Albumin resuscitation protects against traumatic/hemorrhagic shock-induced lung apoptosis in rats

Abstract

Objective: To determine the effects of albumin administration on lung injury and apoptosis in traumatic/hemorrhagic shock (T/HS) rats.

Methods: Studies were performed on an in vivo model of spontaneously breathing rats with induced T/HS; the rats were subjected to femur fracture, ischemia for 30 min, and reperfusion for 20 min with Ringer's lactate solution (RS) or 5% (w/v) albumin (ALB), and the left lower lobes of the lungs were resected.

Results: Albumin administered during reperfusion markedly attenuated injury of the lung and decreased the concentration of lactic acid and the number of in situ TdT-mediated dUTP nick-end labelling (TUNEL)-positive cells. Moreover, immunohistochemistry performed 24 h after reperfusion revealed increases in the level of nuclear factor kappaB (NF-kappaB), and phosphorylated p38 mitogen-activated protein kinase (MAPK) in the albumin-untreated group was down-regulated by albumin treatment when compared with the sham rats.

Conclusion: Resuscitation with albumin attenuates tissue injury and inhibits T/HS-induced apoptosis in the lung via the p38 MAPK signal transduction pathway that functions to stimulate the activation of NF-kappaB.

Fig. 1

The mean blood pressure was monitored throughout the experimental period. The MAP at baseline was (81±11.9) mmHg. All animals exhibited a sharp drop in their MAP immediately after hemorrhage induction (10 min), and no significant differences in the end-resuscitation blood pressure were observed between the T/HS+RS and T/HS+ALB groups when compared with the sham group. The data shown are the mean±SEM recorded for each rat group

Fig. 2

Effects of albumin treatment on (a) the plasma lactic acid (LA) and (b) the PaO₂/FiO₂ ratio in T/HS-affected rats. Blood samples were obtained before hemorrhage induction (baseline), after hemorrhage induction (shock), and at 1, 3, and 24 h postresuscitation. The data are expressed as the mean±SD. ^* P<0.05 and ^# P<0.01, T/HS+RS group vs T/HS+ALB group

Fig. 2

Effects of albumin treatment on (a) the plasma lactic acid (LA) and (b) the PaO₂/FiO₂ ratio in T/HS-affected rats. Blood samples were obtained before hemorrhage induction (baseline), after hemorrhage induction (shock), and at 1, 3, and 24 h postresuscitation. The data are expressed as the mean±SD. ^* P<0.05 and ^# P<0.01, T/HS+RS group vs T/HS+ALB group

Fig. 3

Effects of albumin treatment on T/HS-induced cellular apoptosis in the lungs. (a) DNA-strand fragmentation, as demonstrated by TUNEL technique. The positive (apoptotic, red arrow) nuclei were stained brown during the TUNEL reaction, and the negative ones were stained blue; (b) Percentage of TUNEL-positive cells in lungs obtained from all the rat groups. ^# P<0.01, T/HS+RS group vs T/HS+ALB group

Fig. 3

Effects of albumin treatment on T/HS-induced cellular apoptosis in the lungs. (a) DNA-strand fragmentation, as demonstrated by TUNEL technique. The positive (apoptotic, red arrow) nuclei were stained brown during the TUNEL reaction, and the negative ones were stained blue; (b) Percentage of TUNEL-positive cells in lungs obtained from all the rat groups. ^# P<0.01, T/HS+RS group vs T/HS+ALB group

Fig. 4

(a) Immunolabelling of phospho-p38 and phospho-NF-κB p65 in the lungs obtained from the albumin-treated and untreated rats and the sham group rats; (b) Intensities of phospho-p38 and phospho-NF-κB p65 immunolabelling. A semiquantitative scoring system was used to determine the staining intensity (scored 0~3 for the lowest to highest intensity) and the proportion of stained cells (scored 0~4 for 0% to more than 70% cells stained). ^* P<0.05 and ^# P<0.01, T/HS+RS group vs T/HS+ALB group for the lung tissue samples

Fig. 4

(a) Immunolabelling of phospho-p38 and phospho-NF-κB p65 in the lungs obtained from the albumin-treated and untreated rats and the sham group rats; (b) Intensities of phospho-p38 and phospho-NF-κB p65 immunolabelling. A semiquantitative scoring system was used to determine the staining intensity (scored 0~3 for the lowest to highest intensity) and the proportion of stained cells (scored 0~4 for 0% to more than 70% cells stained). ^* P<0.05 and ^# P<0.01, T/HS+RS group vs T/HS+ALB group for the lung tissue samples