Figure 1.
HT, mild hypothermia group; NT, normothermia group; BC, blank control group; VF, ventricular fibrillation; CPR, cardiopulmonary resuscitation; ROSC, restoration of spontaneous circulation; NDS, neurologic deficit scores; F, female; M, male.
Table 1.
Experimental conditions.
Figure 2.
0 represents for normal and 400 for brain death. Values are given as median ± interquartile range. *p<0.01 vs.NT-24 h group; **p<0.01 vs. NT-72 h group. HT, mild hypothermia group; NT, normothermia group; BC, blank control group; ROSC, restoration of spontaneous circulation.
Figure 3.
Malondialdehyde (MDA) (A) and protein carbonyls (B) in mitochondria isolated from the swine frontal cortex.
Results are expressed as nmol/mg mitochondrial protein (mean ± SD). *p<0.05 vs. BC group; #p<0.01 vs. NT-24 h group. HT, mild hypothermia group; NT, normothermia group; BC, blank control group; ROSC, restoration of spontaneous circulation.
Figure 4.
Activities of respiratory enzymes and MnSOD in mitochondria isolated from the swine frontal cortex.
Respiratory enzyme (A and B) and MnSOD (C) activities are expressed as a ratio of citrate synthase activity (mean ± SD). *p<0.05 vs. BC group; #p<0.01 vs. NT group. HT, mild hypothermia group; NT, normothermia group; BC, blank control group; ROSC, restoration of spontaneous circulation. CS, citrate synthase.
Figure 5.
Expressions of MnSOD, and cytoplasmic, nuclear and total Nrf2 protein in the swine frontal cortex.
The expressions of MnSOD (A) and Nrf2 (B) protein were measured by western blotting (left) using appropriate antibodies in the BC (n = 5), NT-24 h (n = 6), HT-24 h (n = 7), NT-72 h (n = 5) and HT-72 h (n = 7) groups. The OD of each band was measured using Image J software, and the values of MnSOD, and cytoplasmic, nuclear and total Nrf2 protein were normalized to Porin, GAPDH, Lamin B2 and β-actin, respectively (right). Data are expressed as the mean ± SD. *p<0.05 vs. BC group; #p<0.05 vs. NT-24 h group. HT, mild hypothermia group; NT, normothermia group; BC, blank control group; ROSC, restoration of spontaneous circulation; OD, optical density.
Figure 6.
Effects of mild hypothermia on Nrf2 and MnSOD mRNA expressions in the swine frontal cortex.
The mRNA levels for MnSOD (A) and Nrf2 (B) were quantified with real-time PCR. The data were normalized to β-actin. The fold changes of Nrf2 and MnSOD mRNA were calculated relative to the BC group, and results are presented as the mean fold of the blank control ± SD (n = 5, 6 or 7 animals for each group). *p<0.05 vs. BC group; #p<0.05 vs. NT-24 h group. HT, mild hypothermia group; NT, normothermia group; BC, blank control group; ROSC, restoration of spontaneous circulation.
Figure 7.
Representative microscopic changes in the cortex and hippocampus.
Hematoxylin and eosin stained sections (×200), in the precentral gyrus of the frontal lobe (A and B) and CA1 area of the hippocampus (C and D) at 24 h following ROSC, showed changes in damaged neurons, including an eosinophilic cytoplasm, loss of Nissl substance and nuclear pyknosis (arrows). The number of damaged neurons from hypothermic pigs (B and D) was markedly decreased when compared to normothermic pigs (A and C).
Figure 8.
Representative electron micrographs of mitochondria (×100,000).
Mitochondria were isolated from the swine frontal cortex at 24 h following ROSC. A: normal mitochondria with intact membrane cristae and a smooth matrix in the blank control group. B: slightly damaged mitochondria with basically normal cristae and a slightly damaged matrix in the hypothermia group. C: markedy deranged mitochondria with disrupted cristae and a damaged matrix in the normothermia group. Scale bar = 500 µm.