Low hematocrit worsens cerebral injury after prolonged hypothermic circulatory arrest in rats.
OBJECTIVE
This study tests the hypothesis that low hematocrit (Hct) worsens cerebral injury after prolonged hypothermic circulatory arrest (HCA) in rats, and the mechanism involves variable expression of the genes C-Fos, Bcl-2 and Bax.


METHODS
A rat HCA model was developed, and 40 animals were randomly assigned to four groups: Sham (sham) group, or Hct groups of Hct 10%, Hct 20% and Hct 30%. After 90 min of HCA at 18 degrees C, physiologic variables were recorded and brain morphological changes were evaluated with light and electron microscopy. Expressions of C-Fos, Bcl-2, Bax in various brain areas were measured by the reverse transcriptase polymerase chain reaction and standard immunohistochemistry techniques.


RESULTS
The number of injured neurons in the hippocampus CA1 and parietal cortex in the Hct 10% group (CA1: 11.44 +/- 2.52; cortex: 13.65 +/- 2.31) exceeded the mean number of injured neurons in the Hct 20% group (CA1: 8.29 +/- 1.31; cortex: 10.68 +/- 1.24; P < 0.05) and the Hct 30% group. Mean mitochondrial injury scores were greatest at lower Hct levels, while the expression of C-Fos and Bax were highest in the Hct 10% group and lowest in the Hct30% group (P < 0.05). In contrast, the expression of the Bcl-2 mRNA was greatest in the Hct 30% group (P < 0.05).


CONCLUSIONS
Low Hct worsens cerebral injury after prolonged HCA and CPB in rats, which may relate in part to the variable expression of the genes C-Fos, Bcl-2 and Bax.
Dian-San
Su
S
Department of Anesthesiology, RenJi Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200127, China.
Xiang-Rui
Wang
W
Yongjun
Zheng
Z
Yan-Hua
Zhao
Z
D000818:Animals; D001921:Brain / Q000378:metabolism / Q000473:pathology*; D050792:Circulatory Arrest, Deep Hypothermia Induced / Q000009:adverse effects*; D006400:Hematocrit; D006438:Hemodilution / Q000009:adverse effects*; D006624:Hippocampus / Q000378:metabolism / Q000473:pathology; D008297:Male; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology; D009474:Neurons / Q000473:pathology; D010296:Parietal Lobe / Q000378:metabolism / Q000473:pathology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013788:Thalamus / Q000378:metabolism / Q000473:pathology; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
D019253:Proto-Oncogene Proteins c-bcl-2; D016760:Proto-Oncogene Proteins c-fos; D051028:bcl-2-Associated X Protein