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KMID : 0350519950480041047
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Journal of Catholic Medical College
1995 Volume.48 No. 4 p.1047 ~ p.1060
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The Difference in Ischemia-Reperfusion Injury According to Body Temperature and Muscle Location n Rat Hind Limb Muscle
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Abstract
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It remains to be a problem that successful revascularization and reperfusion of ischemia are associated with high systemic complication rates and severe local tissue injuries. The mortality rates after revascularization have been reported to
range
from
10% to 25% and the amputation rates from 12% to 22%. Thus, a good, clinical, functional recovery occurs in 60-70% of survivors and one third of patients show a viable but nonfunctioning extremity in spite of revascularization Such complications
with
nonfunction are primarily related to the injuries that occur in the reperfusion process, the exact mechanism of which is not clear yet. Most of the conventional methods of evaluationg the skeletal muscle injury in ischemia are typically indirect
and
imprecise. However, the nitroblue tetrazolium (NT) staining can distinguish the normal skeletal muscle from the injured on the basis of the positive stain in the normal and negative stain in the injured, permiting the histochemical quantitation.
The purpose of this study is to establish whether the NT staining can accurately assess the extent of the postischemic skeletal muscle necrosis and to investigate the influences of body temperature change and muscle location on muscle necrosis in
a
Wistar rat model with skeletal muscle ischemiareperfusion injury.
Fifty six Wistar male rats were divided into twwo experimental groups and one control group : normothermic group (NTG, 37±0.5℃; n=24), hypothermic group (HTG; 24±0.5℃; n=24) and control group (n=8, laparotomy only). Ischemia-reperfusion
injury
was
induced by two ligations of the immediate infrarenal and suprabifurcational regions of the abdominal aorta for 5 hr and reperfusion for 1 1/2 hr.
The injuries of the adductor muscle (AM) of the upper hind limb and the calf muslce (CM) of the lower hind limb were assessed by NT staining and computerized planimetry (Image Analysis System, Kontron, Vidas, West Germany). Water contents of
muslce,
serum CPK and transmission electron microscopic examination were also performed in the same experimental setting.
@ES The results were as follows :
@EN 1. The reperfusion phase muscle damage with negative NT stain was noted in 51.3±9.5% of AM and 45.9±8.6% of CM in the NTG compared to significantly milder injury of 37.4±7.3% and 39.2±7.2%, respectively, in the ischemic phase (P<0.005).
In
the
HTG the reperfusion phase mucsle injury was noted in 35.6±4.9% of AM and 33.6±8.4% of CM, respectively, compared to 30.1±6.3% and 32.1±7.8% in the ischemic phase. The differences were not significant. On the other hand, the analysis according
to the
muscle location revealed severer muscle injury in AM than in CM (p<0.005).
2. The water contents of AM and CM in the NTG were 78.5±5.3% and 74.1±5.4%, respectively, in the reperfusion phase compared to 74.8±5.1% and 73.8±5.4%, respectively, in the ischemic phase. The differences were statistically significant
(P<0.05). In
the HTG the water contents of AM and CM were 72.4±5.8%, respectively, in the reperfusion phase compared to 71.4±5.6% and 71.8±5.6% in the ischemic phase. The differences were statistically not significant. On the other hand, the analysis
according to
the muscle location revealed significant increase in water content in the NTG compared to the HTG regardless of muscles 9P<0.005), but the increase was more prominent in AM than in CM (P<0.0050.
3. Serum CPK was significantly increased in both experimental groups and the degree of increase was significantly greater in the NTG than the HTG (P<0.005).
4. Electron microscopic study showed intermyofibrillar edema with myofibrillar separation, mitochondrial swelling, disorganization of cristae, nuclear chromatin clumping, and sarcolemmal membrane disruption after reperfusion in both experimental
groups. Such pathological changes were severer in the NTG than in the HTG.
From the above results it is concluded that the ischemia-reperfusion injuries were less severe in the low body temperature. Thus, clinically the low body tfemperature may be used for a beneficial treatment of such injuries. It was also found that
the
injuries were less severe in the calf muscle than in the adductor muscle. The nitroblue tetrazolium staining was able to accurately differentiate the viable from the necrotic muscles. The method appears to be useful in the estimation of the
extent
of
muscle necrosis after ischemia0-reperfusion injury.
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