Abstract
Evaluation of the Mean Arterial Pressure (MAP) and body temperature changes in a new model of liver ischemia-reperfusion applying topical Hypothermia and Ischemic Preconditioning (IPC). Rats (n= 32) were divided in 5 groups: Control (C), Normothermic Ischemia (NI), Ischemic Preconditioning (IPC), Hypothermia 26 degrees C plus IPC (H+IPC) and Hypothermia 26 degrees C (H). MAP and body temperature were recorded at 30 minutes intervals throughout the entire experiment. The study groups underwent 90 minutes partial hepatic ischemia followed by 120 minutes of reperfusion. The median and lateral left lobes were isolated and topical 26 degrees C hypothermia was induced by superfusion of cooled saline solution in H+IPC and H groups. A 10 minutes protocol of ischemia and reperfusion was applied in the IPC and H+IPC groups before the major ischemic insult. There was no significant difference in MAP and body temperature means between the groups throughout the experiments. The present model allows the induction of topical hepatic hypothermia associated or not to IPC. New studies to evaluate the possible synergistic effects of these tools can be reproduced without significant changes in macrohemodynamics and body temperature, or in other words, under stable conditions.
Highlights
During major liver resections, blood flow to the liver can be temporarily occluded to prevent massive blood loss
During the 90 minutes of ischemia, body temperature means ranged from 36.5 ± 0.1°C - 36.9 ± 0.3 °C in the C group, 36.5 ± 0.2 °C - 37.0 ± 0.2 °C in the Isquemia normotérmica (IN) group, 36.5 ± 0.1°C - 36.9 ± 0.3 °C in the Ischemic Preconditioning (IPC) group, 37.0 ± 0.1°C - 37.4 ± 0.1 in the Hypothermia 26°C plus IPC (H+IPC) groups and 35.8 ± 0.5 °C - 36.5 ± 0.4°C in the H group
During 90 minutes of ischemia, Mean Arterial Pressure (MAP) means ranged from 76.5 ± 3.1 mmHg – 83.5 ± 3.1 mmHg in the C group, 86.3 ± 3.8 mmHg - 101.0 ± 5.8 mmHg in the IN group, 90.7 ± 5.4 mmHg 97.9 ± 6.1 mmHg in the IPC group, 84.7 ± 3.8 mmHg – 90.6 ± 4.3 mmHg in the H+IPC group and 88.0 ± 5.6 mmHg – 96.0 ± 4.6 mmHg in the H group
Summary
Blood flow to the liver can be temporarily occluded to prevent massive blood loss. Evidences shows that normal livers tolerate 60 minutes of ischemia without sustaining significant injuries[1,2,3]. In order to attenuate the ischemia-reperfusion injuries and perform complex liver resections, some authors recommend the use of protective tools, such as Hypothermia and IPC. These techniques have been related to the reduction of oxidative stress, less ATP consumption and microcirculation protection[3,5]. IPC is an inducible and potent endogenous mechanism by which repeated episodes of brief Ischemia and Reperfusion (I/R) lead to a state of protection against subsequent sustained I/R injury. Due to simplicity and easy execution, the IPC has been evaluated in many experimental and clinical situations[9,10,11,12]
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