| Objection:The ischemic injuries of skeletal muscle are common diseases in clinic.Ischemia-reperfusion injury(I/R)is a pathological phenomenon that while ischemic tissues were reflowed, dysbolismus and disorganization of histiocyte will get worse. Prevention and cure of ischemia-reperfusion injury had been a focus.Ischemic preconditioning(IPC)is a method that short term ischemia and reperfusion interrupted may improve the tolerance of skeletal muscle.Functions of IPC had been already improved through different animal experiments.However there have no consistent standard of IPC treatment.Whether or not protective effects of different IPC treatments are different? Which IPC treatment would protect skeletal muscle hardest? There is no a consistent opinion about those questions at present. Based on above-mentioned questions,rabbits were made I/R -like models in this experiment to study protective effects of different Ischemic preconditioning treatments against Ischemic-Reperfusion injury.Expect to find which IPC treatment would protect skeletal muscle hardest.Methods:Fifty-six healthy rabbits(2.2-2.7 kg weight)were used in the experiment.The animals were divided randomly into seven groups with eight rabbits in each:an I/R group,six IPC groups(an A group,a B group,a C group,a D group,an E group and an F group).The blood flows of the rabbits limbs were stopped with a special pneumatic tourniquet.The I/R group underwent a 4 hour ischemia directly.The IPC groups were subjected to 4 hour ischemia directly after different ischemic preconditioning treatments(5 or 10 minutes of ischemia and 5 or 10 minutes of reperfusion respectively,for 2-4 cycles),an The contents of CPK,AST in the serum dry to wet ratio of skeletal muscle after 4 hour reperfusion were measured to observe protective effects of different ischemic preconditioning treatments.All the experimental data was analyzed by SPSS 11.0.Results:1 CPK,AST in blood serum.The contents of CPK, AST in the serum of all groups at 2 hours after reperfusion are higher than normal.At 2 hours after reperfusion,CPK(9267.2±671.2),AST(246.7±18.2)in I/R group was significantly superior to that of other groups(P＜0.01).CPK(4621.6±297.6), AST(117.6±8.6)in E group was significantly inferior to that of other groups(P＜0.05).In groups with same IPC duration CPK(8414.5±634.4),AST(156.8±11.3)in B group was significantly inferior to that of A and C group(P＜0.05). CPK(4621.6±297.6),AST(117.6±8.6)in E group was significantly inferior to that of D and F group(P＜0.05).In groups with same IPC cycles,at 2 hours after reperfusion,CPK AST in D group was significantly inferior to that of A group(P＜0.05),CPK AST in F group was significantly inferior to that of C group(P＜0.05).There were no significant difference between B group and F group,C group and D group(P＞0.05).(Table 1,3,4)2 Dry to wet ratio(D/W)of skeletal muscle.At 2 hours after reperfusion,D/W in test group was significantly inferior to that of control groups(P＜0.01).D/W in I/R group(0.1630±0.016) was significantly inferior to that of other test groups(P＜0.01). D/W in E group(0.2780±0.028)was significantly superior to that of other test groups(P＜0.05).In groups with same IPC duration,D/W in B group was significantly superior to that of A and C group(P＜0.05).D/W in E group was significantly superior to that of D and F group(P＜0.05).In groups with same IPC cycles,at 2 hours after reperfusion,D/W in D group was significantly superior to that of A group(P＜0.05),D/W in F group was significantly superior to that of C group(P＜0.05).There were no significant difference between B group and F group,C group and D group(P＞0.05).(Table 2,5)Conclusions:1 IPC may improve the tolerance of skeletal muscle to I/R,bu it is not infinite.2 Five minutes of ischemic preconditioning(IPC5)could protect skeletal muscle of ischemia against necrosis.In same IPC cycles the effects of IPC10 were significantly superior to that of IPC5.Two cycles of ischemic preconditioning could protect skeletal muscle of ischemia against necrosis.Three cycles of IPC is optimal,and protective effects of IPC with four cycles go down but it is better than that of IP5.There were no significant difference between 5 minutes of IPC,4 cycles and 10 minutes of IPC,2 cycles.There were no significant difference between 5 minutes of IPC,3cycles and 10 minutes of IPC,4 cycles.3 The trend of protective effect of IPC on ischemia-reperfusion injury of the muscle in rabbit's first rise to the peak and then go down,10 minutes of IPC,3cycles is optimal. |
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