大鼠蛛网膜下腔出血后脑局部血流量与血脑屏障动态变化

目的：探讨大鼠蛛网膜下腔出血（SAH）后局部脑血流（rCBF）与血脑屏障（BBB）超微结构的动态变化规律和尼莫地平（Nim）的作用特点。方法：通过大鼠枕大池自体血注入法制备SAH后脑血管痉挛（CVS）模型，在SAH后1h、4h、12、24h、3d、7d、14d、及21d等不同时相点，利用激光普勒技术和电镜对各组大鼠局部脑血流与血脑屏障超微结构变化进行观察。结果：SAH后大鼠的rCBF明显下降且具有“两期”反应，在SAH后1h后rCBF有所恢复，4h后再度降低，并可持续至21d。BBB损害改变在SAH后早期即可观察到。Nim对rCBF降低和BBB损害均有改善作用。结论：SAH后rCBF与BBB超微结构的动态变化符合CVS的发展规律，可以反映该时期CVS的状态。早期应用Nim可以改善SAH后CVS，并对BBB的损害有一定保护作用。     

Acute cerebral tissue oxygenation changes following experimental subarachnoid hemorrhage

Abstract

Primary brain ischemia following subarachnoid hemorrhage is a major cause of morbidity and mortality. This study aims to determine whether changes in cerebral tissue oxygenation are related to cerebral blood flow changes in the acute phase following experimental subarachnoid hemorrhage. The endovascular puncture model was used to study subarachnoid hemorrhage in male Wistar rats with a tissue oxygenation probe and a laser Doppler probe placed contralateral to the side of hemorrhage. Following the subarachnoid hemorrhage intracranial pressure rose to 53.0 ± 9.8 mmHg (mean ± SEM). This was associated with a fall in cerebral blood flow to 43.9% ± 7.1% of its baseline value and a fall in tissue oxygenation to 42.8% ± 7.7% of baseline. The time course of the fall and recovery in tissue oxygenation was closely correlated to that of the cerebral blood flow (r = 0.66, p = 0.02). The fall in cerebral blood flow was associated with a 42.1% ± 6.47% fall in the concentration of moving blood cells and a rise of 181.2% ± 27.2% in velocity indicating acute microcirculatory vasoconstriction. Interstitial tissue oxygenation changes mirrored changes in cerebral blood flow indicating that a change in oxygen delivery was occurring.     

Acute cerebral tissue oxygenation changes following experimental subarachnoid hemorrhage

Primary brain ischemia following subarachnoid hemorrhage is a major cause of morbidity and mortality. This study aims to determine whether changes in cerebral tissue oxygenation are related to cerebral blood flow changes in the acute phase following experimental subarachnoid hemorrhage. The endovascular puncture model was used to study subarachnoid hemorrhage in male Wistar rats with a tissue oxygenation probe and a laser Doppler probe placed contralateral to the side of hemorrhage. Following the subarachnoid hemorrhage intracranial pressure rose to 53.0 +/- 9.8 mmHg (mean +/- SEM). This was associated with a fall in cerebral blood flow to 43.9% +/- 7.1% of its baseline value and a fall in tissue oxygenation to 42.8% +/- 7.7% of baseline. The time course of the fall and recovery in tissue oxygenation was closely correlated to that of the cerebral blood flow (r = 0.66, p = 0.02). The fall in cerebral blood flow was associated with a 42.1% +/- 6.47% fall in the concentration of moving blood cells and a rise of 181.2% +/- 27.2% in velocity indicating acute microcirculatory vasoconstriction. Interstitial tissue oxygenation changes mirrored changes in cerebral blood flow indicating that a change in oxygen delivery was occurring.     

Decrease in cerebral blood flow in rats after experimental subarachnoid hemorrhage: a new animal model

There continues to be a need for good animal models of experimental subarachnoid hemorrhage (SAH). The rat would be an ideal subject in which to study SAH since it is inexpensive and easier to use than the larger laboratory animals. The present study was undertaken to determine if alterations of cerebral blood flow could be produced in the rat after experimental SAH, and thereby justify using the rat as a model for further study of SAH. Rats weighing between 450 and 500 grams underwent insertion of a cannula into the cisterna magna at least 5 days prior to physiological testing. One group of rats then received a 0.3 cc injection of fresh autologous arterial blood into the cisterna magna to simulate a SAH. Another group of rats received injection of an equal volume of mock CSF (buffered saline) into the cisterna magna. A third group of rats had no subarachnoid injections. In all three groups, blood flow to the cerebral hemispheres was measured with the labeled microsphere technique. Rats with experimental SAH showed a 40% decrease of cerebral blood flow, whereas rats with saline injections showed only a 15% decrease. Control rats had no changes of cerebral blood flow. These studies demonstrate that the rat is a potential experimental model for investigations into SAH.     

Effect of vardenafil on cerebral vasospasm following experimental subarachnoid hemorrhage in rats

We examined the effects of the phosphodiesterase 5 (PDE-5) inhibitor vardenafil on cerebral vasospasm in an experimental rat subarachnoid hemorrhage (SAH) model. Thirty-two albino Wistar rats were divided into five groups: G1, no experimental intervention; G2, administered subarachnoid physiological saline after sham surgery; G3, subjected to SAH; G4, subjected to SAH and administered low-dose (0.5 mg/kg) vardenafil treatment; and G5, subjected to SAH and administered high-dose (5 mg/kg) vardenafil treatment. For animals in G3, G4 and G5, SAH was induced by an injection of autologous non-heparinized blood into the cisterna magna. Immediately after SAH, for animals in G4 and G5, vardenafil was administered by gavage at intervals of 8 hours for 2 days. The rats were then decapitated, and basilar arteries and blood samples were taken for biochemical and histopathological examination. Malonyldialdehyde values in G2 (p = 0.004) and G3 (p = 0.002) were significantly higher than those in G1. G4 and G5 had significantly lower values than G2 and G3 (p = 0.014, G4 v. G2; p = 0.005, G4 v. G3; p = 0.005, G5 v. G2; p = 0.002, G5 v. G3). Total antioxidant capacity (TAC) values in G3 were significantly lower than those in G1 (p = 0.041). TAC values in G4 and G5 were significantly higher than those in G3 (p = 0.043). Mean luminal diameter in G3 was significantly smaller compared with G1 and G2 (p = 0.002), but larger in G4 (p = 0.002) and G5 (p = 0.001) compared with G3. Mean luminal diameter was also significantly larger in G5 than in G2 (p = 0.008) and G4 (p = 0.038). Mean wall thickness in G2 (p = 0.015) and G3 (p = 0.002) was significantly thicker compared with G1. Wall thickness was significantly thinner in G4 and G5 compared with G2 and G3 (p = 0.008, G4 v. G2; p = 0.001, G4 v. G3; p = 0.005, G5 v. G2; p = 0.001, G5 v. G3). Our results confirm that vardenafil may induce vasodilatation and provide potential benefits in SAH therapy by preventing vasospasm.     

实验性脑血管痉挛时一氧化氮与超氧化物歧化酶对脑血流的作用研究

目的 探讨一氧化氮（ＮＯ）、超氧化物歧化酶（ＳＯＤ）分别及联合使用对大鼠实验性蛛网膜下腔出血（ＳＡＨ）后脑血管痉挛（ＣＶＳ）时脑血流（ＣＢＦ）的作用。方法 将３０只大鼠随机分成５组（每组６只）。Ａ组：假手术＋盐水,Ｂ组：ＳＡＨ＋盐水;Ｃ组：ＳＡＨ＋ＳＯＤ;Ｄ组：ＳＡＨ＋ＮＯＣ１２;Ｅ组：ＳＡＨ＋ＳＯＤ、ＮＯＣ１２。模拟制成４８ｈ后,通过Ｌａｓｅ－Ｄｏｐｐｌｅｒ血液仪观察各种药物持续静脉注射１ｈ内Ｃ     

Effects of graded hyperventilation on cerebral blood flow autoregulation in experimental subarachnoid hemorrhage.

An impaired CBF autoregulation can be restored by hyperventilation at a PaCO2 level of about 2.9 to 4.1 kPa (22 to 31 mm Hg). However, it is uncertain whether the restoring effect can take place at lesser degrees of hypocapnia. In the current study, CBF autoregulation was studied at four PaCO2 levels: 5.33 kPa (40 mm Hg, normoventilation), 4.67 kPa (35 mm Hg, slight hyperventilation), 4.00 kPa (30 mm Hg, moderate hyperventilation), and 3.33 kPa (25 mm Hg, profound hyperventilation). At each PaCO2 level, eight rats 2 days after experimental subarachnoid hemorrhage (SAH) and eight sham-operated controls were studied. The CBF was measured by the intracarotid 133Xe method. The CBF autoregulation was found to be intact in all controls but completely disturbed in the normoventilated SAH rats. However, by slight hyperventilation, CBF autoregulation was restored in seven of eight SAH rats with a decline in CBF of 10%. The CBF autoregulation was found intact in all of the moderately or profoundly hyperventilated SAH rats, whereas the decline in CBF was 21% and 28%, respectively. In conclusion, hyperventilation to a PaCO2 level between 4.00 and 4.67 kPa (30 to 35 mm Hg) appears to be sufficient for reestablishing an impaired autoregulation after SAH.     

Impact of cerebral microcirculatory changes on cerebral blood flow during cerebral vasospasm after aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE: Cerebral microcirculatory changes during cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) are still controversial and uncertain. The aim of this study was to investigate the changes of cerebral microcirculation during cerebral vasospasm and to clarify the roles of microcirculatory disturbances in cerebral ischemia by measuring cerebral circulation time (CCT) and regional cerebral blood flow (rCBF). METHODS: In 24 cases with aneurysmal SAH, rCBF studies by single-photon emission CT and digital subtraction angiography (DSA) were performed on the same day between 5 and 7 days after SAH and/or within 4 hours after the onset of delayed ischemic neurological deficits. CCT was obtained by analyzing the time-density curve of the contrast media on DSA images and was divided into proximal CCT, which was the circulation time through the extraparenchymal large arteries, and peripheral CCT, which was the circulation time through the intraparenchymal small vessels. They were analyzed in association with rCBF and angiographic vasospasm. RESULTS: Severe angiographic vasospasm statistically decreased rCBF, and correlation between the degree of angiographic vasospasm and rCBF was seen (r=0.429, P=0.0006). Peripheral CCT showed strong inverse correlation with rCBF (r=-0.767, P<0.0001). Even in none/mild or moderate angiographic vasospasm, prolonged peripheral CCT was clearly associated with decreased rCBF. CONCLUSIONS: In addition to the marked luminal narrowing of large arteries detected as severe angiographic vasospasm, microcirculatory changes detected as prolonged peripheral CCT affected cerebral ischemia during cerebral vasospasm. These results suggested that impaired autoregulatory vasodilation or decreased luminal caliber in intraparenchymal vessels may take part in cerebral ischemia during cerebral vasospasm.     

Effects of morphine and naloxone on cerebral blood flow and metabolism in experimental subarachnoid hemorrhage

Objective - Naloxone is reported to improve the clinical condition of patients with subarachnoid hemorrhage (SAH). If this effect is vascular determined is unknown, wherefore the influence of morphine and naloxone on cerebral blood flow (CBF) and metabolic rate of oxygen (CMRO_z) after SAH was evaluated. Material and methods - Two groups of 8 rats each with SAH and 2 corresponding groups of controls were investigated. CBF was calculated by the intracarotid ¹³³Xenon method and CMRO₂ as the product of CBF and the difference between systemic arterial and cerebral venous oxygen content. Results - In controls morphine, 1 mg/kg administered intravenously, decreased CBF by 25% ( P < 0.001) without changing the CBF/CMRO₂ ratio. In animals with SAH CBF was decreased by 32% ( P < 0.001) and CBF/CMRO₂ ratio by 38% ( P < 0.01). Naloxone, 40ug/kg administered intravenously neither influenced CBF nor the CBF/CMRO₂ ratio in the 2 groups. Conclusion - The reported clinical effect of naloxone after SAH can, according to our results, not be explained by changing the relationship between CBF and metabolism.     

Effect of melatonin on cerebral vasospasm following experimental subarachnoid hemorrhage

OBJECT: The current study was undertaken to determine whether melatonin therapy reverses vasospasm and prevents apoptosis by inhibiting lipid peroxidation in an experimental subarachnoid hemorrhage (SAH) model. MATERIALS AND METHODS: The rabbits were divided into four groups as follows: Group 1, SAH + melatonin (5 mg/kg/i.p. BID) simultaneously with SAH (n = 6); Group 2, SAH + melatonin (5 mg/kg/i.p. BID) treated 2 hours after SAH (n = 6); Group 3, control group (n = 4); Group 4, SAH only (n = 6). Light microscopic examinations of the basilar arteries were performed to demonstrate the pathophysiological changes of the arterial wall with hematoxylin- eosin. Apoptosis: Immunohistology using the ApopTag Peroxidase In Situ Apoptosis Detection Kit was used to demonstrate apoptosis in a cross section of basilary arteries. Apoptotic index was calculated as the number of the immunoreactive nuclei per total number of endothelial cells, and expressed as a percentage. RESULTS: The results of measurements of diameters of the vessels between groups were significantly different (p = 0.028). While basilar arteries of the SAH only group showed 57% constriction, Groups 1 and 2 were calculated as 33 and 26% constriction, respectively, compared with the control group (p < 0.05). And also Groups 1 and 2 showed significant protection of apoptosis compared with Group 4. The difference between the four groups was tested by Kruskal-Wallis test and the significance between the two groups was tested by Mann- Whitney U-test. CONCLUSION: Melatonin with its strong antioxidant effect can prevent SAH-induced vasospasm and apoptosis of endothelial cells of vessels.     

Regional cerebral metabolic activity in the rat following experimental subarachnoid hemorrhage

A new experimental model was employed to investigate alterations of cerebral metabolic activity in rats subjected to extensive subarachnoid hemorrhage (SAH). The hemorrhages were produced in anesthetized animals by inserting 0.37 ml fresh autologous arterial blood into the subarachnoid space. Rats that underwent sham operations received subarachnoid injections of mock CSF to study the effects of sudden raised intracranial pressure (ICP). Forty-eight hours after subarachnoid injection, the unanesthetized rats were given intravenous injections of [14C]2-deoxyglucose. Experiments were terminated 45 min later by decapitation, and the brains were removed and frozen. Regional brain metabolic activity was studied employing quantitative autoradiography. In comparison with control animals, cerebral metabolic activity was diffusely decreased following SAH. Statistically significant decreases in metabolic activity of less than 34% were observed in 17 of 30 brain regions studied. The largest percentage reductions were in regions displaying the highest basal metabolic rates. Subarachnoid injections of mock CSF also produced depression of cerebral metabolic activity, but quantitatively these changes were not as pronounced as in the hemorrhage group. These studies demonstrate regional changes in brain function following SAH. The data relate these changes to both the presence of blood in the subarachnoid space and sudden raised ICP.     

盐酸法舒地尔对蛛网膜下腔出血后血管痉挛的实验研究

目的通过建立大鼠蛛网膜下腔出血（SAH）模型,探讨盐酸法舒地尔对蛛网膜下腔出血后血管痉挛的缓解作用和神经保护作用,并与尼莫地平对比,观察疗效。方法通过枕大池二次注血法建立大鼠SAH模型,观察基底动脉和海马神经元形态变化,测量基底动脉管径和管壁厚度,计算海马CA1区神经元密度,检测基底动脉内皮型一氧化氮合成酶（eNOS）的表达。结果各组模型大鼠的基底动脉均出现血管痉挛,海马CA1区正常神经元数目明显减少,多数神经元发生变性,基底动脉的eNOS表达明显减弱。但注射法舒地尔组与其他模型组相比能较大程度的缓解以上变化,具有统计学差异（P〈0.05）,且优于尼莫地平。结论法舒地尔可以有效缓解SAH后的迟发性脑血管痉挛,具有神经保护作用,其缓解迟发性脑血管痉挛作用和神经保护作用与动脉壁产生的一氧化氮（NO）有关。     

大鼠蛛网膜下腔出血（SAH）后局部脑皮层血流量及脑水肿观察

本文研究了大鼠SAH后局部脑皮层血流量及脑组织中H2O、Na^ ,^ 含量的变化。结果表明：SAH后30min双侧大脑半球的脑血流量明显下降（P＜0．01），1h，下降至最低点，约为注血前的36％－38％，双侧大脑半球无明显区别，以后脑血流量部分恢复，低血流量状态维持48h以上，一周恢复正常，提示可能有急性脑血管痉挛的发生，SAH后4h脑组织中水含量才明显增加（P＜0．01），48h达到高峰，Na^ 的变化与水含量一致，说明有脑水肿的发生，但脑水肿出现的时间及高峰明显迟于脑血流的降低，提示SAH后脑水肿的发生、发展是脑血流量降低的继发性病理变化。     

Accumulation of intimal platelets in cerebral arteries following experimental subarachnoid hemorrhage in cats

From 2 hours to 23 days following experimental subarachnoid hemorrhage, the accumulation of indium-111-labeled platelets on the intimal surface of the middle cerebral artery was studied in 23 cats. Subarachnoid hemorrhage was produced by transorbital rupture of the right middle cerebral artery. Of the 23 cats, 17 exhibited right middle cerebral artery/left middle cerebral artery radioactivity ratios of greater than 1.25. When these results were compared with those of 12 control cats, 0.001 less than p less than 0.005 (chi2 test). Thus, the results from the control and experimental groups are significantly different and indicate early (after 2 hours) preferential accumulation of intimal platelets in the ruptured right middle cerebral artery compared with the unruptured left middle cerebral artery and new platelet deposition continuing for up to 23 days. However, the experimental group did not reveal a clear pattern for platelet accumulation following subarachnoid hemorrhage. There was no simple correlation between the magnitude of the radioactivity ratios and the time after hemorrhage when the cats were killed although the ratios for 2 hours to 7 days seemed greater than those for 8 to 23 days. Assuming the pivotal role of platelets in the angiopathy of subarachnoid hemorrhage, the administration of antiplatelet agents as soon as possible following its occurrence may be of value.     

Biphasic cerebral blood flow velocity profile in patients with aneurysmal subarachnoid hemorrhage

Introduction: Increases in cerebral blood flow velocity (CBFV) as measured by transcranial Doppler (TCD) sonography are reflective of cerebral vasospasm in patients with aneurysmal subarachnoid hemorrhage (SAH). In serial TCD measurements, some patients exhibit CBFV temporal profiles with two peaks (biphasic). The significance of this finding remains unclear. This retrospective case-control study was conducted to investigate the characteristics and possible predictors of biphasic CBFV profiles. Methods: Biphasic CBFV profiles were identified in serial TCD examinations (every 1–2 days) of 182 consecutive patients admitted for aneurysmal SAH based on CBFV profiles of the middle cerebral artery on the side of higher maximum velocity. Patients undergoing angioplasty were excluded. Patients meeting these criteria (study patients) were compared to control patients matched for age and Hunt and Hess grade. Results: Eighteen patients (9.9%) demonstrated biphasic CBFV profiles. The first CBFV (134±11 cm/second) peak occurred on post-SAH day 6±1, and the second peak (148±12 cm/second) on day 13±1. Study patients more often exhibited focal (p<0.05) symptoms at the time of the first peak. No patient deteriorated neurologically at the time of the second peak. No correlation was observed between CBVF and mean arterial pressure or central venous pressure trends. Conclusion: Serial TCD assessment identifies patients with SAH and a biphasic CBFV temporal profile. Although the second peak usually is not associated with a worsening of symptoms, these patients were more likely to exhibit clinical symptoms during the first CBFV peak.     

The effects of hyperoxemia on cerebral blood flow in subarachnoid hemorrhage patients

The effects of oxygen inhalation at atmospheric pressure (1 ATA.O2) on CBF were studied in subarachnoid hemorrhage (SAH) patients due to ruptured intracranial aneurysms to prove the usefulness of the "O2 response" test for the evaluation of the cerebral vascular response. "O2 response" means the CBF (or ICP) decrease during hyperoxemia. CBF was measured by 10 m Ci 133Xe intravenous injection method using rCBF analyzer BI-1400 (Valmet). Two-compartmental analysis was used for the calculation of initial slope index (ISI). Studied cases were 53 postoperative SAH patients and 100 times examinations were done under the condition of Rest-1 ATA.O2. The incidence of global disturbance of the O2 response was 33% from day 0 to 3, 31% during day 4 to 7, 30% during day 8 to 14, and 23% at day 15 to 30. But, after day 31, there was no case which revealed an impaired O2 response. It was not possible to detect focal or hemispheric abnormalities of the O2 response because of the limitation of noninvasive two-dimensional CBF measurement method employed. The causes of O2 response abnormality, within a month after the onset, were increased ICP, hydrocephalus and diffuse brain damage. Multiple regression analysis proved that elevated PaO2 is the major factor in reducing CBF. CBF and ICP correlation study showed that the higher the Rest ICP, the fewer the CBF decreases during pure O2 inhalation. This may indicate that the increase in ICP in the acute stage changes the O2 response according to the level of increased ICP.(ABSTRACT TRUNCATED AT 250 WORDS)     

Magnesium sulfate reverses experimental delayed cerebral vasospasm after subarachnoid hemorrhage in rats

We induced experimental delayed cerebral vasospasm by the intracisternal injection of greater than 0.5 ml blood in 30 rats. Seventy-two hours later the basilar artery was exposed via the transclival approach and photographed at high-power magnification through an operating microscope. We then evaluated the effect of topical (n = 30) and intravenous (n = 20) magnesium sulfate on the spastic artery by computerized image analysis. A greater than 50% reduction in baseline diameter of the basilar artery was observed in the rats subjected to subarachnoid hemorrhage compared with the 10 controls (p less than 0.0001). Intravenous magnesium sulfate dilated the spastic artery to approximately 75% of the baseline diameter in control rats (p less than 0.0001). Topical magnesium sulfate caused dramatic dilation of the basilar artery in both the control and the subarachnoid hemorrhage groups to near 150% of the baseline diameter in the controls (p less than 0.001). All rats receiving intravenous magnesium sulfate reached therapeutic plasma levels of the ion. Hemodynamic effects were mild and immediately reversible upon cessation of magnesium sulfate administration. We suggest that magnesium has a role in the treatment of subarachnoid hemorrhage-induced vasospasm in humans.