Heart Can Shu Prevention And Treatment Of Transient Ischemic Pharmacological Mechanism Of Experimental Research

The world health organization (WHO) reported that cerebrovascular accident is the third cause of death in world, and it is the second in China (secondary to obstruction barrier, higher than myocardial infarction). The cerebral atherosclerosis caused by hypercholesterolemia is the main pathological basis of cerebral ischemia.Transient ischemic attack (TIA) is characterized with a serious of neurologic dysfunction symptoms, which aggravate less than60minutes and last less than24hours. The initial pathogenesis of TIA is the soluble embolism and reversible spasm of pial arteries. These had been considered as cerebral blood supply disorders. In other words, the cerebral blood flow regulation (total) and neurovascular coupling (distribution) are the related pathophysiological mechanisms. Because TIA could predict stroke and dementia, how to reverse TIA is an important research territory in China.Xinkeshu (XKS) is classic prescription for prevention and treatment Heart Yang deficiency. Based on the theory of "heart governing blood and vessels" and "heart controlling mind", this thesis cooperated with precious studies about XKS treating myocardial infarction, to study the pharmacological mechanisms on XKS treat TIA.The TIA was induced by Fat diet and artery spasm intervention in Japanese rabbits. The high fatty diet was fed for12weeks to induxe insufficiency of cerebral endothelial dilatation, arginine vasopressin (AVP) was intravenously injected for4times to induce pial arterial spasm. Simultaneously, XKS was administrated orally in rabbits to prevent and treat TIA. The results suggested that XKS prevent and treat TIA with dose-dependent. The key mechanisms are to increase NO bioavailability and restore neurovascular coupling regulation.1. Dose-effect relationship of arginine vasopressin induced pial arterial spasmAim To test the ECG of VP induced myocardial ischemia in rabbits and investigate the dose-effect relationship.Methods One hundred male Japanese rabbits were randomly divided into10groups (n=10each), the body weight was not significantly different between the groups. Ten doses of arginine vasopressin (AVP) were designed as295.28-2952.76mU/kg (k=0.5). After AVP was intravenously injected, the rabbits were monitored with electrocardiogram, transient resistance arterial spasm was judged as ST-segment elevation (more than0.1mV). Then the AVP accumulated dose (PAD) and median effective dose (ED50) were calculated.Results The PAD and ED50of AVP for inducing spasm are1449.0±38.7mU/kg and1414.0mU/kg at physiological status in rabbits. The rabbits which their PAD is lower than ED50are sensitive to AVP stimulation.Conclusion Intravenous injection of AVP to induce transient resistance arterial spasm is dose-dependent and dose-effective curves had the similar S shapes. 2. AVP-induced model of transient ischemic attack with hyperlipidemia in rabbitsAim To test myocardial ischemia ECG of rabbits with cerebral atherosclerosis (CAS) and intravenously inject AVP to establish the TIA model.Methods Thirty-six AVP sensitive rabbits are randomly divided into3groups. The Control rabbits ware intervened with vehicle. The Model rabbits were fed with high fatty diet for12weeks, and intravenously injected with AVP to induce ECG ischemia and establish TIA model. The XKS rabbits were fed with high fatty diet with5.0mg/kg XKS to determine the endothelium dependent of the model. The pathological changes were observed to confirm cerebral AS. The PAD and ED50of AVP, and the time-effect relationship with hyperlipidemia induced by high fatty diet were calculated.Results As age increased, the dose-effect curves of AVP of rabbits in3group were all shifted to the right, suggesting that endogenous high cholesterol play roles in pial artery reactivity, including reduced endothelial relaxation and decreased smooth muscle cell potency. High fatty diet caused the AVP dose-response curves shift to the right; oral administration of XKS reduced the degree of right shift. During the moderate and severe hypercholesterolemia period, PAD showed significant difference (P<0.05). The area under the curve (AUC) was negatively correlated with the pathological changes (P<0.05). The pathological changes included hypercholesterolemia, area of atherosclerotic plaques, thickened carotid artery intimal, Nissl staining volume ratio in precentral gyrus of cerebral cortex (neuronal degeneration degree), granular cell density per volume in hippocampal CAl region (neuronal loss degree) and edema volume ratio surrounded vessels in precentral gyrus of cerebral cortex (endothelial injury).Japanese male rabbits were fed with high fatty diet for12weeks continually, intravenously injected with AVP for4times to induce resistance artery spasm, then the rabbit model for human TIA was established. In this mode, the changes of pathological and physiopathological potency consisted with the features of human TIA, such as cholesterol metabolism, accompanied lesion, degree of endothelial injury, resistance arteries reactivity, motor cortex degeneration and hippocampal neurons loss, et.al. The aging mechanisms due to cumulative effects of endogenous oxidative stress lead to TIA, the hypercholesterolemia with hypothyroidism and cholesterol synthesis activation promoted TIA, and the AVP induced pial resistance arterial spasm triggered and induced TIA.Conclusion The TIA model induced by high fatty diet and pial arterial spasm in rabbits, basically matched the pathophysiological charactes of clinical patients with TIA. This model could used to candidate discovery and clinical risk assessment.3. Pathogenic pharmacodynamic action of xinkeshu on transient ischemic attackThe cerebral atherosclerosis, via triggering embolism and spasm, is the major pathogenic factor of TIA. In clinical and experimental studies, the carotid atherosclerosis represented pial arterial lesions.Aim To investigate the effects of XKS on TIA through inhibiting basic pathological changes of pial arteries.Methods According to the PAD and ED50of AVP for inducing resistance arterial spasm, PAD<ED5o was considered as the inclusion criteria to select72male Japanese rabbits that is sensitive to arterial spasm. The rabbits were randomly divided into6groups with different diet for84days (n=12each, the body weight, sensitivity and plasma cholesterol balance were not significant difference among each group):Control (standard diet), Model (high fatty diet), Positive (high fatty diet with5.0mg/Kg atorvastatin), XKS with low, middle or high dose (high fatty diet with184.8,369.6or739.2mg/kg XKS). After intravenously injected with AVP, the ECG ischemia appeared d00, d28, d56and d84.The blood was collected and metabolite biomarkers were measured at doo and d84. At d85, rabbits were rats were anesthetized with chloral hydrate sodium subcutaneously, perfusion fixation was performed, then the carotid initiate segment was embedded in paraffin, sectioned (6μm), and stained with hematoxylin-eosin (HE) to quantify intima volume ratio and Masson to quantify deposited collagen volume ratio. The precentral gyrus of cerebral cortex was also embedded in paraffin, sectioned (6μm), and stained with HE to quantify edema volume ratio surrounded capillaries. Statistical significance was calculated using Student’s t test between groups, P<0.05was significant.Results In addition to lipid changes and AS pathological changes, the carotid intima-volume ratio represented anterior pial arterial stenosis, the carotid deposited collagen volume ratio represented the relax resistance of anterior pial arteries, and the capillary edema represented endothelial injury after the attack.(A)Artery stenosis①Compared with the Control group, the arterial lumen narrowed in other groups (intima obviously thickened); all treatment groups showed obvious significant difference (P<0.01), suggesting that stenosis existed in model.②Compared with the Model group, all treatment groups showed obvious significant difference (P<0.01), suggesting that treatment were effective.③Compared with the Positive group, the intima in Low and Middle dose groups thickened (P<0.01), the high dose group thinned (P<0.01), suggesting the effect of High dose group was better than Positive group.④XKS had the dose-dependent tendency (P<0.01).(B)Relax resistance①Compared with the Control group, the deposited collagen ratios in Model group and Positive group increased (P<0.01) respectively, suggesting that relax resistance increased.②Compared with the Model group, these decreased in Positive group, Low dose group, Middle dose group and High dose group (P<0.01), suggesting that treatment were effective.③Compared with the positive group, these increased in Low dose group and Middle dose group(P<0.01). and decreased High dose group (P<0.01).④XKS had the dose-dependent tendency (P<0.01).(C)Capillary edema:It increased in Model group(P<0.01) and relived in Positive group(P<0.01).①Compared with the Control group, the edema ratios in Model group and Positive group increased (P<0.01) by192.56、3.27、79.02、7.38、1.423times respectively, suggesting that microvascular injury.②Compared with the Model group, these decreased by97.79%、58.66%、95.67%、98.75%in Positive group, Low dose group, Middle dose group and High dose group (P<0.01), respectively, suggesting that treatment were effective.③Compared with the positive group, these increased in Low dose group and Middle dose group (P<0.01), and decreased in High dose group (P<0.01).KS had the dose-dependent tendency (P<0.01).Conclusion Although XKS did not significantly relieve hypercholesterolemia, it could alleviate artery stenosis, decrease relaxation resistance and reversal endothelial injury, which involved in preventing and treating TIA. According to the pathophysiological features of familial hypercholesterolemia, the mechanisms related to increase bioavailability of dilate substances in cerebral circulation.4. Pathogenic pharmacology of xinkeshu on transient ischemic attackThe bioavailability of dilate substances in cerebral circulation involved in the pathogenic pharmacology of XKS. Nitric oxide (NO) is the dilate substance which had rapidest onset and strongest effect. Extracellular superoxide dismutase (ecSOD) is the key enzyme effect on protect NO. EcSOD could enhance NOSs derived NO bioavailability, which are the focus to reasearch.Aim Based on the in situ distribution of NOSs and ecSOD, to investigate that the pharmacological effect of XKS on TIA was related to increase of NO bioavailability.Methods72male Japanese rabbits that is sensitive to arterial spasm were selected. The rabbits were randomly divided into6groups with different diet for84days (n=12each): Control (standard diet), Model (high fatty diet), Positive (high fatty diet with5.0mg/Kg atorvastatin), XKS with low, middle or high dose (high fatty diet with184.8,369.6or739.2mg/kg XKS). After intravenously injected with AVP for4times, the ECG ischemia appeared. The blood was collected and metabolite biomarkers were measured at d00and d84. At d85, rabbits were rats were anesthetized with chloral hydrate sodium subcutaneously, perfusion fixation was performed, then the right carotid artery initiate segment was embedded in paraffin, sectioned (6μm). The expression of ecSOD, iNOS and eNOS were assessed with immunohistochemistry and quantified (OD/V) by morphometry. The left carotid artery initiate segment was carefully cut for RTPCR. The mRNA expression of ecSOD, iNOS and eNOS were measured, the relative levels were calculated as2-△△ct. Statistical significance was calculated using Student’s t test between groups, P<0.05was significant. Through confirming the source of NO and the transfer efficiency was to determine NO bioavailability. Results The EcSOD in arteries protected iNOS and eNOS, reversed the nitration modification which injured artery relaxation and thrombolytic function.(A)EcSOD IHC levels①Compared with the Control group, the levels of ecSOD decreased98.07%,66.81%,93.58%,87.11%,23.35%in other groups(P<0.01) respectively, suggesting that the antioxidative effect decreased in model.②Compared with the Model group, these in treatment groups increased;all treatment groups showed obvious significant difference (P<0.01), suggesting that treatment could increase antioxidative effect.③Compared with the Positive group, these decreased in Low dose group and Middle dose group (P<0.05) and increased in High dose group (P<0.01), suggesting the effect of High dose group was better than Positive group.KS rescued ecSOD levels with dose-dependent (P<0.01).ecSOD-mRNA The Control group showed the highest ecSOD mRNA potency as the base line(0.00±0.45, P<0.01), the Model group showed the highest reduction (1.00±0.01, P<0.01). These in treatment groups in descending order were as follows:Positive group (0.81±0.02, P<0.01),High dose group (0.74±0.03, P<0.01), Middle dose group (0.88±0.00, P<0.01) and Low dose group (0.93±0.01, P<0.01); suggesting that the increase of antioxidative effect related to upregulation of ecSOD expression and enhancement of synthesis and release of this enzyme.(B)iNOS IHC levels①Compared with the Control group, the levels of iNOS increased significantly in other groups(P<0.01); suggesting that iNOS increased in model.②Compared with the Model group, these in treatment groups decreased significantly (P<0.01).③Compared with the Positive group, these increased in Low dose group and Middle dose group (P<0.01) but decreased in High dose group (P<0.01).KS rescued ecSOD levels with dose-dependent (P<0.01).iNOS-mRNA The Control group showed the highest iNOS mRNA potency as the base line (0.00±0.13, P<0.01), the Model group showed the highest increasing extent(1.00±0.03, P<0.01). These in treatment groups in descending order were as follows:High dose group (0.76±0.07, P<0.01), Positive group (0.85±0.01, P<0.01), Middle dose group (0.83±0.01, P<0.01) and Low dose group (0.91±0.03, P<0.01); suggesting that the increase of antioxidative effect related to upregulation of iNOS expression and enhancement of NO release.(C)eNOS IHC levels①Compared with the Control group, the levels of eNOS decreased in all groups(P<0.01); suggesting that eNOS decreased in model.②Compared with the Model group, all other groups showed obvious significant difference (P<0.01); suggesting that treatment could increase NO release.③Compared with the Positive group, these decreased in Low and Middle dose group (P<0.05) but increased in High dose group (P<0.01); suggesting the effect of High dose group was better than Positive group.④XKS rescued ecSOD levels with dose-dependent (P<0.01). eNOS-mRNA The Control group showed the highest iNOS mRNA potency as the base line (0.00±0.07, P<0.01), the Model group showed the highest reduction (1.00±0.01, P<0.01). These in treatment groups in descending order were as follows:High dose group (0.81±0.02, P<0.01), Positive group (0.91±0.00, P<0.01), Middle dose group (0.92±0.00, P<0.01) and Low dose group (0.96±0.00, P<0.01); suggesting that the increase of antioxidative effect related to upregulation of eNOS expression and enhancement of NO release.Conclusion XKS could upregulated local ecSOD expression and increased iNOS and eNOS expression, increase NO bioavailability, relax cerebrel resistance arteries, increase neurovascular coupling regulation, to prevent and treat TIA.5. Protective pharmacodynamic action of xinkeshu on transient ischemic attackBecause of the soluble embolism and reversible spasm attack, when TIA attack, patients had transient neurological dysfunction. After repeated attacks, it showed chronic nerve tissue atrophy, that is the temporal and subsequent braininjury. Abnormal neurovascular coupling is the trigger factor to form vicious circle, the pyramidal neurons in motor cortex and hippocampal granule neurons are the main target cells of the injury.Aim To investigate that XKS prevent TIA through protecting brain from injury.Methods The PAD≤ED50was considered as the inclusion criteria to select72male Japanese rabbits that is sensitive to arterial spasm. The rabbits were randomly divided into6groups with different diet for84days (n=12each, the body weight, sensitivity and plasma cholesterol balance were not significant difference among each group):Control (standard diet), Model (high fatty diet), Positive (high fatty diet with5.0mg/Kg atorvastatin), XKS with low, middle or high dose (high fatty diet with184.8,369.6or739.2mg/kg XKS). After intravenously injected with AVP, the ECG ischemia appeared d00, d28, d56and d84The blood was collected and metabolite biomarkers were measured at d00and d84. At d85, rabbits were rats were anesthetized with chloral hydrate sodium subcutaneously, perfusion fixation was performed, then the precentral gyrus of cerebral cortex and hippocampal CA1region were embedded in paraffin, sectioned (6μm),and stained with HE and Nissl. The Nissl positive stained volume ratio of pyramidal neurons layers in precentral gyrus of cerebral cortex and cellular density of granular cell layers in hippocampal CA1region were morphometried at40×magnification. Values are expressed as the average of five fields taken from section. Statistical significance was calculated using Student’s t test between groups, P<0.05was significant.Results In addition to lipid changes, positive Nissl staining area of represented neuronal degeneration degree, and density of survival cells in hippocampus represented neuronal loss degree.(A) Neuronal degeneration①Compared with the Control group, the Nissl positive stained volume ratio of pyramidal neurons layers in precentral gyrus of cerebral cortex significantly decreased in each group (P<0.01); suggesting that reversible neuronal degenerated in model.②Compared with the Model group, these in treatment groups significantly increased (P<0.01); suggesting that treatment was effective.③Compared with the Positive group, these in Low and Middle dose group showed insufficient recovery (P<0.05) and the High dose group showed higher recovery (P<0.05); suggesting the effect of High dose group was better than Positive group.④XKS rescued neuronal degeneration with dose-dependent (P<0.01).(B) Neuronal loss①Compared with the Control group, the Nissl positive stained volume ratio of pyramidal neurons layers in precentral gyrus of cerebral cortex decreased in each group (P<0.01); suggesting that reversible eNOS decreased in model.②Compared with the Model group, all treatment groups showed obvious significant difference (P<O.01); suggesting that treatment could increase NO release.③Compared with the Positive group, these decreased in Low dose group (P<0.05) and increased in High dose group (P<0.01).④XKS rescued density of survival cells with dose-dependent (P<0.01).(B) Neuronal loss①Compared with the Control group(201.33), the density of survival cells of granular cell layers in hippocampal CAl region decreased in each group; except the High dose group showed significant difference (P<0.05), the other treatment groups showed obvious significant difference (P<0.01); suggesting that neuronal loss existed in model.②Compared with the Model group (67.33), these in treatment groups improved;except the Positive group showed significant difference (P<0.05), the other treatment groups showed obvious significant difference (P<0.01); suggesting that treatment was effective.③Compared with the Positive group (131.33), these decreased in Low dose group (P<0.05), similar in Middle dose group (94.67, P>0.05) and increased in High dose group (180.00, P<0.05); suggesting the effect of High dose group was better than Positive group.④Compared with the Low dose group, these in Middle (P<0.05) and High (P<0.01) dose groups both sincreased.⑤Compared with the Middle dose group, these in High dose group increased (P<0.05), suggesting that the protect effect of XKS for permanent brain damage had dose-dependent tendency.Conclusion Although XKS did not significantly relieve hypercholesterolemia, it could alleviate neuronal degeneration, decrease neuronal loss, inhibit TIA injury, which involved in prevent and treat effects. According to the physiological regulation of neurovascular coupling and pathological mechanisms of TIA, the increase of NO bioavailability in cerebral circulation may take part in the pharmacodynamic actions of XKS.6. Protective pharmacology of xinkeshu on transient ischemic attackThe protective pharmacology of XKS are closely related to NO bioavailability. EcSOD is the key enzyme that protects the production, transfer and effect of NO. EcSOD increases NO bioavailability, which may rescue the feed-forward mechanism of neurovascular coupling.Aim To investigate that ecSOD protect metabolites of NOSs and rescue the feed-forward mechanism of neurovascular coupling, which was the major pharmacological mechanisms of XKSforTIA.Methods72male Japanese rabbits that is sensitive to AVP were selected. The rabbits were randomly divided into6groups with different diet for84days (n=12each, the body weight, sensitivity and plasma cholesterol balance were not significant difference among each group):Control (standard diet), Model (high fatty diet), Positive (high fatty diet with5.0mg/Kg atorvastatin), XKS with low, middle or high dose (high fatty diet with184.8,369.6or739.2mg/kg XKS). The model was confirmed by series of indexes referred above. The ecSOD and NOSs in situ protein levels were accessed by immunohistochemistry, mRNA levels were measured by RT-PCR, and total protein amount were determined by western blot. Statistical significance was calculated using Student’s t test between groups, P<0.05was significant. The regression analysis of4enzymes was calculated to confirm the advanced protect effect of ecSOD.Results Cerebral ecSOD could protect NOSs and reverse nitro modification.(A)EcSOD IHC levels①Compared with the Control group (3.07%), the levels of ecSOD decreased in model groups (P<0.01); suggesting that the antioxidative effect decreased in model.②Compared with the Model group (0.24%), these in treatment groups increased (P<0.01), suggesting that treatment could increase antioxidative effect.③Compared with the Positive group (0.46%), these decreased in Low dose group (P<0.01) and increased in Middle and High dose group (P<0.01), suggesting the superiority effect of XKS.④Compared with the Low dose group (0.63%), these in Middle and High dose groups both increased(P<0.01).⑤Compared with the Middle dose group(0.8%), these in High dose group increased (1.62%, P<0.01), suggesting that the increased protection had the dose-dependent tendency.Results Cerebral ecSOD could protect NOSs and reverse nitro modification.(A)EcSOD IHC levels①Compared with the Control group (3.07%), the levels of ecSOD decreased in model groups (P<0.01); suggesting that the antioxidative effect decreased in model.②Compared with the Model group (0.24%), these in treatment groups increased (P<0.01), suggesting that treatment could increase antioxidative effect.③Compared with the Positive group (0.46%), these decreased in Low dose group (P<0.01) and increased in Middle and High dose group (P<0.01), suggesting the superiority effect of XKS.④Compared with the Low dose group (0.63%), these in Middle and High dose groups both increased(P<0.01).⑤Compared with the Middle dose group(0.8%), these in High dose group increased (1.62%, P<0.01), suggesting that the increased protection had the dose-dependent tendency.ecSOD-mRNA ecSOD mRNA potency in the Control group (0.00±0.11,P<0.01) as baseline, the Model group showed the highest change extent(1.00±0.00). These in treatment groups in descending order were as follows:High dose group (0.30±0.08), Positive group (0.56±0.10), Middle dose group (0.74±0.07) and Low dose group (0.99±0.01); suggesting that the treatment upregulated ecSOD expression, increased antioxidative effect and enhanced of NO potency.(B)iNOS IHC levels①Compared with the Control group (0.07%), the levels of iNOS decreased in model groups; expect for High dose group(P<0.05), other4groups showed obvious significant difference (P<0.01); suggesting that iNOS decreased in model.②Compared with the Model group (0.01%), these in treatment groups increased significantly (P<0.01); suggesting that treatment could increase NO release.③Compared with the Positive group (0.02%), these similar in Low dose group (P>0.05), increased in Middle and High dose group (P<0.01); suggesting superiority effect of XKS.④Compared with the Low dose group (0.03%), these in Middle (0.04%, P<0.05) and High (0.677%, P<0.01) dose groups both increased.⑤Compared with the Middle dose group, these in High dose group increased (P<0.01), suggesting that the NO release had the dose-dependent tendency.iNOS-mRNA iNOS mRNA potency in the Control group (0.0000±0.0767) as baseline, the Model group showed the highest change extent(1.0000±0.1010). These in treatment groups in descending order were as follows:High dose group (0.2588±0.1413), Positive group (0.4513±0.0413), Middle dose group (0.6108±0.0789) and Low dose group (0.8236±0.0473); suggesting that the increase of antioxidative effect related to upregulation of iNOS synthesis.(C)eNOS IHC levels①Compared with the Control group (0.68%), the levels of eNOS decreased in model groups (P<0.01); suggesting that eNOS decreased in model.②Compared with the Model group (0.09%), except the Low dose group showed significant difference (P<0.05), the other treatment groups showed obvious significant difference (P<0.01); suggesting that treatment could increase eNOS levels.③Compared with the Positive group (0.29%), these decreased in Low and Middle dose group (P<0.01), increased in High dose group (P<0.01); suggesting effect of XKS was similar to atorvastatin.④Compared with the Low dose group (0.001%), these in Middle (P<0.05) and High (P<0.01) dose groups both increased.⑤Compared with the Middle dose group (0.16%), these in High dose group increased (0.46%, P<0.01), suggesting that the eNOS levels had the dose-dependent tendency.eNOS-mRNA eNOS mRNA potency in the Control group (0.00±0.03) as baseline, the Model group showed the highest change extent(1.00±0.00). These in treatment groups in descending order were as follows:High dose group (0.14±0.02), Positive group (0.24±0.01), Middle dose group (0.52±0.11) and Low dose group (0.89±0.08); suggesting that XKS could upregulated eNOS expression, increased NO to relax resistance arteries.(D)nNOS IHC levels①Compared with the Control group (0.26%), the levels of nNOS decreased in model groups (P<0.01) suggesting that nNOS decreased in model.②Compared with the Model group (0.07%), these in treatment groups increased significantly (P<0.01); suggesting that treatment could increase nNOS levels.③Compared with the Positive group (0.09%), each dose group of XKS increased significantly(P<0.01); suggesting that the effect of XKS was beeter than atorvastatin.④Compared with the Low dose group (0.12%), these in Middle (P<0.05) and High (P<0.01) dose groups both increased.⑤Compared with the Middle dose group(0.15%), these in High dose group increased (0.20%,,P<0.05), suggesting that nNOS levels had the dose-dependent tendency.nNOS-mRNA nNOS mRNA potency in the Control group (0.00±0.20) as baseline, the Model group showed the highest change extent(1.00±0.00). These in treatment groups in descending order were as follows:High dose group (0.29±0.08), Positive group (0.69±0.03), Middle dose group (0.92±0.03) and Low dose group (0.99±0.01); suggesting that XKS could upregulated nNOS expression, increased NO to relax resistance arteries.Conclusion XKS upregulated ecSOD priority to NOSs, with characteristics of restore feedforward neurovascular coupling. Then, XKS protected oxidative stress from iNOS, increased eNOS for reliving artery spasm, enhanced feedforward of nNOS, which were the leading pharmacological mechanisms of XKS for TIA.In summary, this thesis established TIA model in rabitts, verified the pathogenic and protective and2types of pharmacodynamic action, exploit2types of pharmacological mechanisms. XKS effect on ecSOD to increase NO bioavaliability, protect NOSs, inhibit oxidative stress via iNOS, prevent pial artery spasm via eNOS and enhance feedforward regulation via nNOS.It is a pity that the active compounds of XKS should be determined (There were tissues for further research.).