ABSTRACT
BACKGROUND: Magnetic therapy has a long history and is used in the treatment of various diseases. To study the protective function of constant magnetic field for ischemic cerebrovascular diseases may provide new clinical foundation for non-medicinal and non-traumatic treatment and develop a novel way for treatment with physical factor.OBJECTIVE: To observe the influence of constant magnetic field treatment on hemodynamics at macroscopic level, RBC membrane fluidity at subcellular level and antioxidase activity at molecular level, as well as NO and NO synthetase activity in rats with ischemic-reperfusion (IR) injury.DESIGN: A completely randomized design.SETTING: Biophysical Teaching and Research Department of Harbin Medical University.MATERIALS: This experiment was carried out at Biophysical Laboratory,Harbin Medical University, between May and November 2002. Forty healthy Wistar rats were adaptively raised for 1 week before randomized into 3 groups, namely, sham-operation group (n=10), model group (n=15)and magnetic therapy group (n=15).METHODS: ① IR model of middle cerebral artery (MCA) was established in rats in model group and magnetic therapy group, but MCA was only tied up without occlusion in sham-operation group. ② In magnetic therapy group, rat necks were exposed to 40 mT constant magnetic field instantly after ischemic injury for 30 minutes, once a day, while rats in sham-operation group and model group were not exposed to magnetic field.Three groups of rats were anaesthetized at postoperative 7 days for obtaining blood from eyeball, and cut off head for obtaining brain.MAIN OUTCOME MEASURES: ① Hemodynamic changes in three groups of rats. ② Changes of RBC membrane fluidity-related parameters.③ Changes of serum glutathione peroxidase and ceruloplasmin content.④ Changes of brain malonedialdehyde (MDA), NO, and NO synthetase activity indexes.RESULTS: Thirty rats were included and all entered the result analysis.① Hemodynamic parameters: Blood high-shearing, blood low-shearing viscosity, fibrinogen and HCT were remarkably higher in model group than in sham- operation group (P ＜ 0.01), but obviously lower in magnetic therapy group than in model group (P ＜ 0.01). ② RBC membrane fluidity: The fluorescence polarization, average microviscosity and aeolotropy were remarkably higher in model group than in sham-operation group (P ＜ 0.01), and the above indexes were lower in magnetic therapy group than in model group (P ＜ 0.05). ③ Serum glutathione peroxidase and ceruloplasmin contents in model group were remarkably lower than those in sham-operation group (P ＜ 0.05), but were higher in magnetic therapy group than in model group (P ＜ 0.01), and slightly higher than sham-operation group. ④ The brain Cu/Zn-SOD, MDA, NO, NO synthetase activities in model group were remarkably higher than in sham-operation group (P ＜ 0.05 or 0.01),but antioxidase activity was remarkably lower than that in sham-operation group (P ＜ 0.01); all parameters were proved to get better in magnetic therapy group after magnetic field treatment, and better than those in model group (P ＜ 0.05, 0.01).CONCLUSION: Constant magnetic field exposure can remarkably improve rat hemodynamic property, increase RBC membrane fluidity and antioxidase activity, and reduce the content of MDA, NO, NO synthetase,thereby improving organic anti-oxidation capability and effectively preventing free radicals and NO-induced neural damage. It possesses certain function of protecting brain IR injury through holding up the pathophysiological development of brain ischemia injury.
