Fosphenytoin Reduces Hippocampal Neuronal Damage in Rat Following Transient Global Ischemia

Summary Fosphenytoin, a water-soluble disodium phosphate ester of phenytoin, is a phenytoin prodrug with similar anticonvulsant properties. In this study, we evaluated its neuroprotective properties in a cardiac arrest-induced global ischemia model. After 12 minute ischemia, Long-Evans hooded rats were resuscitated, given fosphenytoin (30 mg/kg, i.m.) or saline 5 minutes after the ischemic episode, and killed on day 7. Brains were removed, fixed, and vibratome sectioned to assess the numbers of normal appearing CAI pyramidal neurons and for immunohistological staining of glial fibrillary acidic protein (GFAP). After global ischemia, the number of hippocampal CA1 pyramidal neurons decreased significantly (from 14.33±1.73 to 2.19±0.16 per 100 μm²). Most hippocampal CA1 pyramidal neurons showed signs of injury and GFAP immunoreactivity of the region increased. With fosphenytoin treatment 5 min after ischemia, hippocampal CA1 pyramidal neurons remained at near control level (13.90±0.92), however, GFAP staining was not significantly changed. Our data, although indicating different neuronal and glial responses following fosphenytoin treatment, nevertheless, suggest that fosphenytoin is an effective neuroprotectant against ischemia-induced damage.     

Effect of Nitrous Oxide on Neuronal Damage and Extracellular Glutamate Concentration as a Function of Mild, Moderate, or Severe Ischemia in Halothane-anesthetized Gerbils

Background: The effect of nitrous oxide on ischemic neuronal damage was quantitatively evaluated by use of logistic regression curves.

Methods: Seventy-two gerbils were anesthetized with 1% halothane and randomly assigned to receive 70% nitrous oxide or 70% nitrogen. Forebrain ischemia was performed for 3, 5, or 7 min, and direct-current potential in the hippocampal CA1 region was recorded. Histologic outcome was evaluated 5 days later. Relations of neuronal damage with ischemic duration and duration of ischemic depolarization were determined by logistic regression curves. In some animals, extracellular glutamate concentration was measured every 60 s during forebrain ischemia.

Results: Nitrous oxide increased neuronal damage only with 5 min of ischemia (nitrous oxide vs. nitrogen: 78.5 +/- 23.0 vs. 37.3 +/- 12.2%; P < 0.01). The percentages of neuronal damage with 3 and 7 min of ischemia were not different with or without nitrous oxide. Logistic regression curves indicated that nitrous oxide significantly increased neuronal damage during the period from 3.07 to 6.63 min of ischemia. Logistic regression curves also indicated that nitrous oxide increased neuronal damage in the condition of the same duration of ischemic depolarization. Nitrous oxide shortened the ischemic duration necessary for causing 50% neuronal damage by 0.82 min. Dynamic change in extracellular glutamate concentration was not different (mean maximum dialysate glutamate concentration: 4.29 +/- 3.09 vs. 4.63 +/- 1.83 [mu]m).     

细胞外高钾对离体鼠心缺血再灌注损伤的保护作用

为了解高钾抗心肌缺血再灌注（Ｉ－Ｒ）损伤的途径。用离体大鼠心脏行冠脉结扎，松扎后作电镜观察和磷酸盐－焦锑酸盐（ＰＰＡ法）细胞化学钙定位及抗氧自由基检测。结果：１３ｍｍｏｌ／Ｌ高钾保护Ｉ－Ｒ心肌超氧化物歧化酶（ＳＯＤ）活力，抑制丙二醛（ＭＤＡ）生成，减少心肌酶的漏出，保存肌膜结合钙的能力，防止钙在线粒体的积聚，减轻心肌超微结构的破坏。实验提示１３ｍｍｏｌ／Ｌ钾能抑制胞内钙超负荷和膜脂质过氧化达到抗Ｉ     

Effects of Dexmedetomidine on Hypoxia-evoked Glutamate Release and Glutamate Receptor Activity in Hippocampal Slices

Background: The selective alpha2 agonist dexmedetomidine may improve neurologic outcome after incomplete ischemia in animals when it is administered either before or after the start of the ischemic insult. To clarify further the mechanisms by which alpha2 agonists may provide neuroprotective effects, the authors tested the hypotheses that dexmedetomidine decreases synaptic and extrasynaptic glutamate release stimulated by potassium chloride or hypoxia, and decreases postsynaptic glutamate receptor activity during aerobic or hypoxic conditions.

Methods: Glutamate released from brain slices (300- micro meter thick) from rat hippocampus was measured in a cuvette during two experimental stresses: (1) potassium chloride-evoked depolarization (30 mM) with and without 10 nM, 100 nM, or 1,000 nM dexmedetomidine; and (2) hypoxia (95% Nitrogen2 - 5% CO2) with and without 100 nM dexmedetomidine. Glutamate release was quantified by fluorescence assay using 1 mM nicotinamide adenine dinucleotide, and 5 international units per ml glutamate dehydrogenase. The formation of nicotinamide dinucleotide reduced from nicotinamide adenine dinucleotide by glutamate dehydrogenase was measured fluorometrically (excitation light 340 nm, emission intensity 460 nm) in the solution above the slice. Glutamate receptor activity was determined by the change in cytosolic calcium concentration in CA1 neurons in the presence and absence of 100 nM dexmedetomidine during administration of N-methyl-D-aspartate (100 micro Meter) and during simulated ischemic penumbra conditions (PO2 = 20 mmHg, glutamate 3 mM). Calcium concentration was measured using a microscope fluorometer in fura 2-loaded rat hippocampal brain slices.

Results: Dexmedetomidine attenuated potassium chloride-evoked glutamate release by 37%, 51%, (P = 0.03) and 27%, respectively, for the 10 nM, 100 nM, and 1,000 nM concentrations, and decreased (at 100 nM) the increase in glutamate release in response to hypoxia by 61% (P <0.0001). Dexmedetomidine (100 nM) had no effect on N-methyl-D-aspartate or hypoxia plus 3 mM L-glutamate-mediated calcium changes.     

Etomidate Does Not Alter Recovery after Anoxia of Evoked Population Spikes Recorded from the CA1 Region of Rat Hippocampal Slices

Background: Etomidate is an anesthetic agent that reduces the cerebral metabolic rate and causes minimal cardiovascular depression. Its ability to improve recovery after anoxia or ischemia is equivocal. An in vitro neuronal preparation was used to examine the action of etomidate on electrophysiologic and biochemical parameters during and after anoxia.

Methods: The Schaffer collateral pathway was stimulated, and a postsynaptic evoked population spike was recorded from the CA1 pyramidal cell layer of rat hippocampal slices. Etomidate or propylene glycol, its solvent, was present 15 min before, during, and 10 min after anoxia. Adenosine triphosphate, sodium, and potassium concentrations were measured at the end of anoxia in tissue treated with etomidate, propylene glycol, or with no added drugs.

Results: Etomidate did not alter recovery after 6 min of anoxia. The population spikes from untreated slices recovered to 32% of their preanoxic amplitude, and slices treated with 0.5, 3, and 30 micro gram/ml etomidate recovered to 24%, 35%, and 13%, respectively. Slices treated with propylene glycol, equivalent to that in 3 and 30 micro gram/ml etomidate, recovered to 46% and 12%, respectively, and this was not significantly different from untreated slices. Etomidate did not attenuate the decrease in adenosine triphosphate concentrations during anoxia. The increase in sodium and the decrease in potassium during anoxia were significantly attenuated by 30 but not by 3 micro gram/ml etomidate.     

异丙酚对新生大鼠海马CA1区兴奋性突触反应的影响

目的：研究异丙酚对新生大鼠海马CAI区兴奋性突触反应的影响。方法：取1周龄Wistar大鼠,快速断头取脑,用振动切片机切取400μm厚的海马脑片,电刺激靠近海马CA1区的Schaffer纤维,用全细胞膜片钳技术记录CA1区锥体细胞的兴奋性突触后电流（excitatory post—synaptic current,EPSC）。循环液中加入不同浓度的异丙酚,观察其对EPSC的影响。然后给与低频刺激（900pulse,3Hz）诱导长时程抑制（10ng—term depression,LTD）,并观察异丙酚对LTD诱导的影响。结果：异丙酚呈剂量依赖性地抑制EPSC,其怍用可被印防己毒素（picrotoxin,pic）阻断;异丙酚可易化由N-甲基-D-门冬氨酸（N—methvl—D—aspartate,NMDA）受体介导的LTD的诱导。结论：异丙酚可影响新生大鼠海马CA1区的兴奋性突触传递和突触可塑性,从而对大鼠的学习和记忆产生影响。     

己酮可可碱在肺缺血-再灌注损伤中的作用

目的　探讨己酮可可碱 (PTX)对肺缺血 -再灌注损伤的保护作用。　方法　 72只大鼠随机分为 3组 ,每组 2 4只。 组 :未行缺血及再灌注处理 ; 组 :行左肺缺血和再灌注处理 ; 组 :行左肺缺血和再灌注处理 ,并给予己酮可可碱。采用在体肺温缺血 -再灌注损伤的模型 ,于缺血 45分钟、再灌注 1小时、2小时和 4小时进行动脉血气分析、肺组织含水量、支气管肺泡灌洗液白蛋白含量、血浆和左肺组织丙二醛、左肺组织和支气管肺泡灌洗液髓过氧化物酶(MPO)活性测定。　结果　 组再灌注 2小时和 4小时动脉血氧分压显著降低 ,各时间点左肺含水量、支气管肺泡灌洗液白蛋白含量、血浆丙二醛、左肺组织、支气管肺泡灌洗液中髓过氧化物酶均显著升高 ,PTX可改善上述指标变化。结论　 PTX通过抑制中性粒细胞肺内聚集 ,减轻肺血管内皮细胞损伤程度 ,而防止损伤的发展     

Effects of Hypoxia-Reoxygenation on Microvascular Endothelial Function in the Rat Hippocampal Slice

Background: Cerebral ischemia and hypoxia may cause injury to both neuronal and vascular tissue. The direct effects of hypoxia on endothelial function in intraparenchymal cerebral arterioles are unknown. Using a modification of the rat brain slice preparation, allowing continuous imaging of these previously inaccessible vessels, microvessel dilation was evaluated before and after a brief hypoxic episode.

Methods: Rat brain slices were superfused with oxygenated artificial cerebrospinal fluid. Hippocampal arterioles were visualized using computerized videomicroscopy, and their diameters (range, 12-27 [mu]m) were measured using image analysis. After preconstriction with prostaglandin F2[alpha] and controlled p H and carbon dioxide tension, graded concentrations of either acetylcholine (endothelium-dependent vasodilation) or sodium nitroprusside (endothelium-independent vasodilation) were given before and after a 10-min period of hypoxia.

Results: Sodium nitroprusside (100 [mu]M) caused similar dilation before and after hypoxia (mean +/- SEM: 9.6 +/- 0.6%vs. 13.0 +/- 0.9%). Acetylcholine (100 [mu]M) caused significantly less dilation (P < 0.05) after hypoxia (mean +/- SEM: 9.3 +/- 1.8%vs. 3.6 +/- 1.2%). The decreased acetylcholine-induced dilation after hypoxia was not reversed by pretreatment with L-arginine (1 mM), the precursor of nitric oxide (mean +/- SEM: 8.8 +/- 1.3%vs. 4.4 +/- 0.7%).     

氯沙坦对大鼠肾脏缺血/再灌注损伤中STAT-1及ICAM-1蛋白表达的影响

目的：研究氯沙坦在肾缺血/再灌注损伤中对STAT-1和ICAM-1蛋白表达的影响及在损伤修复过程中的作用。方法：大鼠背部双侧切开找到肾蒂,行无创动脉夹夹闭造成急性肾缺血/再灌注损伤模型,以氯沙坦预处理灌胃,苦味酸法测血清肌酐,免疫组化测肾组织切片中的STAT-1蛋白和ICAM-1蛋白表达的水平。结果：假手术组在6h和24h肾组织的病理和血肌酐数值无明显变化;模型组在缺血再灌注6h和24h与假手术组对比血清肌酐数值明显升高,肾组织切片在6h时STAT-1和ICAM-1蛋白已有表达,24h时两指标表达均明显上调;氯沙坦预处理组在缺血再灌注损伤6h和24h时与模型组对比,血肌酐数值明显下降,同时肾组织中STAT-1和ICAM-1蛋白表达也明显下调。结论：氯沙坦在肾缺血再灌注损伤中起保护作用,机制可能通过下调STAT-1和ICAM-1蛋白表达有关。     

Anesthetics and Mild Hypothermia Similarly Prevent Hippocampal Neuron Death in an In Vitro Model of Cerebral Ischemia

Background: General anesthetics reduce neuron loss following focal cerebral ischemia in rodents. The relative efficacy of this action among different anesthetics clinically used for neuroprotection is uncertain. In addition, it remains unclear how anesthetics compare to neuroprotection afforded by mild hypothermia. This study was performed to evaluate the comparative effects of isoflurane, sodium pentothal, and mild hypothermia in a hippocampal slice model of cerebral ischemia and to determine if the mechanism of neuroprotection of isoflurane involves inhibition of glutamate excitotoxicity.

Methods: Survival and morphology of CA1, CA3, and dentate gyrus neurons in rat hippocampal slices were examined after 10 or 20 min of combined oxygen-glucose deprivation (in vitro ischemia) followed by a 5-h recovery period.

Results: 10 or 20 min in vitro ischemia at 37[degrees]C killed 35-40% of neurons in CA1 (P < 0.001), 6% in CA3 (not significant) and 18% in dentate (P < 0.05). Isoflurane (0.7 and 2.0%, [almost equal to] 0.45 and 1.5 minimum alveolar concentration), pentothal (50 [mu]m, [almost equal to] 1 minimum alveolar concentration equivalent) and mild hypothermia (34[degrees]C) all reduced CA1 cell loss and morphologic damage to similar degrees in 10- and 20-min periods of ischemia (P < 0.001). The noncompetitive N-methyl-d-aspartate antagonist MK-801 prevented cell damage, showing that N-methyl-d-aspartate receptor activation is an important mechanism of injury in this model. Glutamate (1 mm) produced cell loss similar to in vitro ischemia. Isoflurane (2%) prevented cell damage from glutamate exposure.     

Neuroprotective Effects of Dexmedetomidine in the Gerbil Hippocampus after Transient Global Ischemia

Background: Cerebral ischemia induces a massive release of norepinephrine associated with neuronal death in the brain. It has been demonstrated that alpha2 -adrenoceptor agonists decrease the release and turnover of noradrenaline, and this might prove advantageous in counteracting the neurodegeneration in ischemic brain. Therefore, in the present study, the authors tested whether dexmedetomidine, a selective alpha2 -receptor agonist, has neuroprotective effects in a gerbil transient global ischemia model.

Methods: Ischemia was induced by bilateral carotid occlusion for 5 min in diethylether-anesthetized normothermic gerbils. Dexmedetomidine was administered subcutaneously in four different treatment paradigms (6-8 animals/group): 3 or 30 micro gram/kg 30 min before and thereafter at 3, 12, 24, and 48 h after the occlusion, or 3 or 30 micro gram/kg at 3, 12, 24, and 48 h after the occlusion. Control animals were subjected to forebrain ischemia but received only saline injections. One week after occlusion, animals were transcardially perfused for histochemistry. Neuronal death in the CA1 and CA3 regions of the hippocampus and in the hilus of the dentate gyrus was evaluated in silver-stained 60-micro meter coronal sections.

Results: Compared with saline-treated ischemic animals, dexmedetomidine at a dose of 3 micro gram/kg given before and continued after the induction of ischemia reduced the number of damaged neurons in the CA3 area (2 +/- 3 vs. 17 +/- 20 degenerated neurons/mm2; P <0.05). Also in the dentate hilus, the number of damaged neurons was reduced by dexmedetomidine (3 micro gram/kg) given before and continued after ischemia (5 +/- 7 vs. 56 +/- 42 degenerated neurons/mm2; P <0.01).     

罗格列酮对肾大部切除大鼠残肾细胞外基质的影响及其机制

目的：观察罗格列酮对肾大部切除大鼠残肾的细胞外基质（ECM）的影响并探讨其可能的机制。方法：将大鼠随机分为4组，每组8只：假手术组（SHAM组）、肾大部切除组（NX组）、肾大部切除加小剂量罗格列酮治疗组（XL组，罗格列酮5mg.kg^-1·d^-1）和肾大部切除加大剂量罗格列酮治疗组（DL组，罗格列酮15mg·kg^-1·d^-1）。8周后观察大鼠尿蛋白、血BUN、Scr和肾脏病理改变，用免疫组化检测基质金属蛋白酶-2（MMP-2）、基质金属蛋白酶-9（MMP-9）在肾组织中的表达。用天狼星红染色半定量法检测肾脏胶原纤维含量。用RT～PCR的方法测定肾组织中纤连蛋白（FN）的表达。结果：（1）罗格列酮能降低大鼠24h尿蛋白定量、血BUN、Scr，与NX组比较有统计学差异（P〈0.01，P〈0．05）。（2）NX组可见肾小球硬化，ECM增生，肾组织大量胶原纤维沉积。用药后病变减轻，其中大剂量罗格列酮组肾小球MMP-2明显增多；肾小管、间质MMP-9明显减少；肾小球囊壁、肾小球基底膜及肾小管基底膜、血管周围胶原纤维沉积减少。（3）与SHAM组相比，NX组残肾组织FN mRNA的表达均明显升高（P〈0.05），XL组FN mRNA的表达较NX组有所降低，以大剂量XL组为明显（P〈0．01）。结论：罗格列酮可剂量依赖性地降低尿蛋白，改善肾功能肾脏病理损害；减少肾脏胶原纤维沉积和FN的表达；这可能与罗格列酮能抑制肾组织MMP-9表达和上调MMP-2表达有关。     

MMP-3/TIMP-1在大鼠肢体再灌注后关节软骨损伤的作用

目的　探讨缺血再灌注后关节软骨中MMP - 3/TIMP - 1比例变化与软骨损伤的关系。方法　采用大鼠后肢股动脉夹闭的方法模拟缺血再灌注的动物模型 ,用Wistar大鼠 4 0只 ,随机分成正常对照组 (NG)、肢体单纯缺血组 (IG)和缺血再灌注组 (IR)。运用免疫组化技术 ,分别测定TIMP - 1和MMP - 3在关节软骨中不同时相的表达变化并进行半定量分析 ,观察关节软骨病理改变及蛋白多糖 (PG)的变化。结果　缺血再灌注后 ,关节软骨中的MMP - 3和TIMP - 1表达均有增加 ,但MMP - 3增加的幅度大于TIMP ,导致MMP - 3/TIMP - 1比值增大 ,与再灌注后引起的关节软骨损伤相关。结论　MMP/TIMP的失平衡表达是导致缺血再灌注后关节软骨损伤的重要因素     

Neuroprotective Effects of Riluzole and Ketamine during Transient Spinal Cord Ischemia in the Rabbit

Background: Massive release of central excitatory neurotransmitters is an important initial step in ischemic neuronal injury, and modification of this process may provide neuroprotection. We studied the protective effects of the voltage-dependent sodium channel antagonist riluzole and the N-methyl-d-aspartate receptor antagonist ketamine on hind limb motor function and histopathologic outcome in an experimental model of spinal cord ischemia.

Methods: Temporary spinal cord ischemia was induced by 29 min of infrarenal balloon occlusion of the aorta in 60 anesthetized New Zealand white rabbits. Animals were randomly assigned to one of four treatment groups (n = 15 each): group C, saline (control); group R, riluzole, 8 mg/kg intravenously; group K, ketamine, 55 mg/kg intravenously; group RK, riluzole and ketamine. After reperfusion, riluzole treatment was continued with intraperitoneal infusions. Normothermia (38[degrees]C) was maintained during ischemia, and rectal temperature was assessed before and after intraperitoneal infusions. Neurologic function, according to Tarlov's criteria, was evaluated every 24 h, and infarction volume and the number of eosinophilic neurons and viable motoneurons in the lumbosacral spinal cord was evaluated after 72 h.

Results: Neurologic outcome was better in groups R and RK than in groups C and K. All animals in group C (100%) and all animals but one in group K (93%) were paraplegic 72 h after the ischemic insult versus 53% in group R and 67% in group RK (P < 0.01 each). More viable motoneurons were present in groups R and RK than in controls (P < 0.05).     

Effects of Propofol on Sodium Channel-dependent Sodium Influx and Glutamate Release in Rat Cerebrocortical Synaptosomes

Background: Previous electrophysiologic studies have implicated voltage-dependent Na+ channels as a molecular site of action for propofol. This study considered the effects of propofol on Na+ channel-mediated Na+ influx and neurotransmitter release in rat brain synaptosomes (isolated presynaptic nerve terminals).

Methods: Purified cerebrocortical synaptosomes from adult rats were used to determine the effects of propofol on Na+ influx through voltage-dependent Na+ channels (measured using22 Na+) and intracellular [Na+] (measured by ion-specific spectrofluorimetry). For comparison, the effects of propofol on synaptosomal glutamate release evoked by 4-aminopyridine (Na+ channel dependent), veratridine (Na (+) channel dependent), and KCl (Na+ channel independent) were studied using enzyme-coupled fluorimetry.

Results: Propofol inhibited veratridine-evoked22 Na+ influx (inhibitory concentration of 50% [IC50] = 46 micro Meter; 8.9 micro Meter free) and changes in intracellular [Na+] (IC50 = 13 micro Meter; 6.3 micro Meter free) in synaptosomes in a dose-dependent manner. Propofol also inhibited 4-aminopyridine-evoked (IC50 = 39 micro Meter; 19 micro Meter free) and veratridine (20 micro Meter)-evoked (IC (50) = 30 micro Meter; 14 micro Meter free), but not KCl-evoked (up to 100 micro Meter) glutamate release from synaptosomes.     

Effects of Pentobarbital and Isoflurane on Conditioned Learning after Transient Global Cerebral Ischemia in Rabbits

Background: The acquisition of a conditioned eyeblink response has been used extensively to study the neurologic substrates of learning and memory. We examined the effects of the anesthetics isoflurane and pentobarbital, or hypothermia (30[degrees]C), on the ability of rabbits to acquire an eyeblink conditioned response after 6.5 min of cerebral ischemia.

Methods: New Zealand white rabbits (n = 48) were randomly assigned to sham, normothermic, hypothermic, isoflurane, or pentobarbital groups. In the normothermic, hypothermic, isoflurane, and pentobarbital groups, 6.5 min of global cerebral ischemia was produced. In animals randomized to the isoflurane and pentobarbital groups, a pattern of burst suppression was achieved on the electroencephalogram before the start of the ischemic episode. Animals in the hypothermia group were cooled to 30[degrees]C before ischemia. Seven days after ischemia, eyeblink training was started using an audible tone presented for 100 ms as the conditioned stimulus. The unconditioned stimulus was an air puff directed at the cornea. The delay between the end of conditioned stimulus and the start of the unconditioned stimulus (the trace interval) was 300 ms in duration. A conditioned response was defined as an eyeblink that was initiated during the trace interval. Eighty trials per day and 15 days of training were delivered.

Results: Neurologic deficits were greatest in the normothermia group, and these animals also had fewer conditioned responses than those in the sham, hypothermia, or pentobarbital groups. Animals in the isoflurane group had an intermediate number of conditioned responses that was not significantly different from the normothermia group.     

The Effect of Graded Postischemic Spinal Cord Hypothermia on Neurological Outcome and Histopathology after Transient Spinal Ischemia in Rat

Background: Previous data have shown that postischemic brain hypothermia is protective. The authors evaluated the effect of postischemic spinal hypothermia on neurologic function and spinal histopathologic indices after aortic occlusion in the rat.

Methods: Spinal ischemia was induced by aortic occlusion lasting 10 min. After ischemia, spinal hypothermia was induced using a subcutaneous heat exchanger. Three studies were conducted. In the first study, the intrathecal temperature was decreased to 34, 30, or 27 [degree sign]C for 2 h beginning with initial reperfusion. In the second study, hypothermia (target intrathecal temperature 27 [degree sign]C) was initiated with reflow and maintained for 15 or 120 min. In the third study, the intrathecal temperature was decreased to 27 [degree sign]C for 2 h starting 5, 60, or 120 min after normothermic reperfusion. Animals survived for 2 or 3 days, at which time they were examined and perfusion fixed with 4% paraformaldehyde.

Results: Normothermic ischemia followed by normothermic reflow resulted in spastic paraplegia and spinal neuronal degeneration. Immediate postischemic hypothermia (27 [degree sign]C for 2 h) resulted in decreasing motor dysfunction. Incomplete protection was noted at 34 [degree sign]C. Fifteen minutes of immediate cooling (27 [degree sign]C) also provided significant protection. Delay of onset of post-reflow hypothermia (27 [degree sign]C) by 5 min or more failed to provide protection. Histopathologic analysis revealed temperature-dependent suppression of spinal neurodegeneration, with no effect of delayed cooling.     

Effects of Delayed Administration of Low-dose Lidocaine on Transient Focal Cerebral Ischemia in Rats

Background: The authors' previous study demonstrated that a clinical antiarrhythmic dose of lidocaine, when given before ischemia, is neuroprotective in a rat model of transient focal cerebral ischemia. In this study, the authors investigated whether the administration of this dose of lidocaine, when delayed until 45 min after the onset of ischemia, also reduces ischemic brain injury.

Methods: Lidocaine was administered as an intravenous bolus (1.5 mg/kg) followed by an intravenous infusion (2 mg [middle dot] kg-1 [middle dot] h-1) for 165 min, beginning 45 min after the onset of a 90-min period of transient focal cerebral ischemia. Control animals were given the same volume of saline. Focal cerebral ischemia was induced by occluding the right middle cerebral artery using an intraluminal suture. Neurologic outcome and body weight loss were quantified 7 days later. The brain was fixed 7 days after ischemia and brain sections were stained with hematoxylin and eosin for assessment of infarct size and the number of intact neurons. In separate experiments, local cerebral blood flow and the electroencephalogram were measured during ischemia and 180 min into the reperfusion period. Infarct size was assessed after 24 h.

Results: Infarct size, at either 24 h or 7 days after ischemia, was not significantly reduced in the lidocaine group. However, the number of intact neurons was significantly increased in both the ischemic penumbra and core of the lidocaine group 7 days after ischemia, compared with the vehicle group. Rats treated with lidocaine demonstrated better neurologic outcome and less weight loss (P < 0.05). Lidocaine treatment had no significant influence on local cerebral blood flow and electroencephalogram during ischemia and reperfusion.     

Protective Effects of Antithrombin III Supplementation on Warm Ischemia and Reperfusion Injury in Rat Liver

p < 0.01), and the recovery of tissue blood flow markedly improved ( p < 0.01) compared to the saline-treated group (control group). Leakages of aspartame aminotransferase, alanine aminotransferase, and lactate dehydrogenase were mitigated in the AT III group ( p < 0.05). Ultrastructural alterations of sinusoidal endothelial cells were markedly reduced in the AT III group. The PGI ₂ level at the end of reperfusion was significantly elevated ( p < 0.01) in the AT III group compared to the control group. The results of this study indicated that pretreatment with AT III significantly improved the energy status and microcirculation, as well as histologic damage, after liver ischemia and reperfusion. One of the fundamental effects of AT III might be mediated through the production of prostacyclin.