Moderate Hypothermia Provides Better Protection of the Intestinal Barrier than Deep Hypothermia during Circulatory Arrest in a Piglet Model: A Microdialysis Study.
BACKGROUND
This study aimed to assess the effects of different temperature settings of hypothermic circulatory arrest (HCA) on intestinal barrier function in a piglet model.


METHODS
Twenty Wuzhishan piglets were randomly assigned to 40 min of HCA at 18°C (DHCA group, n = 5), 40 min of HCA at 24°C (MHCA group, n = 5), normothermic cardiopulmonary bypass (CPB group, n = 5) or sham operation (SO group, n = 5). Serum D-lactate (SDL) and lipopolysaccharide (LPS) levels were determined. Microdialysis parameters (glucose, lactate, pyruvate and glycerol) in the intestinal dialysate were measured. After 180 min of reperfusion, intestinal samples were harvested for real-time polymerase chain reaction and western blotting measurements for E-cadherin and Claudin-1.


RESULTS
Higher levels of SDL and LPS were detected in the DHCA group than in the MHCA group (P < 0.001). Both MHCA and DHCA groups exhibited lower glucose levels, higher lactate and glycerol levels and a higher lactate to pyruvate (L/P) ratio compared with the CPB group (p<0.05); the DHCA group had higher lactate and glycerol levels and a higher L/P ratio (p<0.05) but similar glucose levels compared to the MHCA group. No significant differences in E-cadherin mRNA or protein levels were noted. Upregulation of claudin-1 mRNA levels was detected in both the DHCA and MHCA animals' intestines (P < 0.01), but only the DHCA group exhibited a decrease in claudin-1 protein expression (P < 0.01).


CONCLUSIONS
HCA altered the energy metabolism and expression of epithelial junctions in the intestine. Moderate hypothermia (24°C) was less detrimental to the markers of normal functioning of the intestinal barrier than deep hypothermia (18°C).
The Second Department of Cardiac Surgery, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
Mengya
M
Liang
The Second Department of Cardiac Surgery, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
Kangni
K
Feng
Assisted Circulatory Laboratory of Health Ministry, Sun Yat-sen University, Guangzhou, China.
Xiao
X
Yang
The Second Department of Cardiac Surgery, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
Guangxian
G
Chen
The Second Department of Cardiac Surgery, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
Zhixian
Z
Tang
The Second Department of Cardiac Surgery, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
Weibin
W
Lin
Department of Cardiopulmonary Bypass, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
Jian
J
Rong
The Second Department of Cardiac Surgery, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, China.
Zhongkai
Z
Wu
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