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KMID : 0390119950350020223
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Journal of Pusan Medical College
1995 Volume.35 No. 2 p.223 ~ p.233
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Effects of Hypothermia on the Changes of Neurotransmitters after Spinal Ischemia in Rats
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Abstract
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Core body temperature is precisely regulated by effective thermoregulatory responses. Themoregulation impairment, prolonged exposure to an extreme cold environment, or both, may lead to a decrease in core temperature and a pathologic state. In
contradistinction to accidental hypothermia, deliberate hyhotermia has been used as a therapeutic adjunct for a variety of medical procedures.
Paresis or fully developed paraplegia, even if not unexpected but hardly pedictable, remains an ever-emerging memento after thoracoadbominal aneurysm repa(?). A number of surgical techniques, including shunts, left atrio-femoral bypass, or
partial
cardiopulmonary bypass, have been tested with the aim of maintaining sufficient distal aortic pressure during aortic crossclamping, thus preventing spinal cord ischemic damage. However, in a number of clinical studies the incidence of paraplegia
has
been noted to be similar to that wit he simple aortic crossclamping method. Similarly, the beneficial effect of cerebrospinal fluid drainage and different pharmacological interventions appears to be time-limited, particularly after prolonged
crossclamping under normothermic conditions.
The deliberate hypothermia has been reported as a possible therapeutic tool against ischemic damage. For evaluating the effect of hypothermia in Sprague Dawley rat, I investigated changes of neurotransmitter, aspartate, glutamate, glycine and
taurine,
during spinal ischemic period and reperfusion period by using intrathecal microdialysis method.
@ES The results were as followed
@EN 1. The concentrations of aspartate and glutamate, excitatory amino acids, were increased by 275% and 250% in normothermic group. These increases were significant different from those in control group (p<0.05), but, there were no significant
differences between control group and hypothermic group.
2. The concentration of glycine and taurine, inhibitory amino acids, were also incrased by 223% and 335% in normothermic group(p<0.05 vs, control group). There were some trends to increase the concentration of glycine and taurine in hypothermic
group,
but there were no significant differences between the control and the thypothermic groups.
3. The histopathologic changes after spinal ischemia in normothermic group occurred at small or medium sized neuron located in the dorsolateral part of anterior. Horn. There was not a such histopathologic change in hypothermic group.
Fro these results, the deleberate hypothermia can attenuate the increase of amino acids neurotransmitters during and after ischemia and may prevent the ischemia-induced neuronal damage during aortic occlusion in aortovascular surgery.
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