Changes of neuronal calcium channel following brain damage induced by injection of pertussin bacilli in rats

OBJECTIVE: To explore changes of neuronal calcium channel following brain damage induced by injection of pertussis bacilli in rats, and to investigate the relationship between cytosolic free calcium concentration ([Ca(2+)](i)) in the synaptosome and Ca(2+)-ATPase activities of mitochondria. METHODS: The level of [Ca(2+)](i) in the synaptosome and Ca(2+)-ATPase activities of mitochondria in the acute brain damage induced by injection of pertussis bacilli (PB) in rat was determined and nimodipine was administrated to show its effects on [Ca(2+)](i) in the synaptosome and on alteration of Ca(2+)-ATPase activity in the mitochondria. Seventy-three rats were randomly divided into four groups, ie, normal control group (Group A), sham-operation control group (Group B), PB group (Group C) and nimodipine treatment group (Group D). RESULTS: The level of [Ca(2+)](i) was significantly increased in the PB-injected cerebral hemisphere in the Group C as compared with that in the Group A and the Group B at 30 minutes after injection of PB. The level of [Ca(2+)](i) was kept higher in the 4 hours and 24 hours subgroups after the injection in the Group C (P<0.05). In contrast, the Ca(2+)-ATPase activities were decreased remarkably among all of the subgroups in the Group C. Nimodipine, which was administered after injection of PB, could significantly decrease the [Ca(2+)](i) and increase the activity of Ca(2+)-ATPase (P<0.05). CONCLUSIONS: The neuronal calcium channel is opened after injection of PB. There is a negative correlation between activities of Ca(2+)-ATPase and [Ca(2+)](i). Nimodipine can reduce brain damage through stimulating the activities of Ca(2+)-ATPase in the mitochondria, and decrease the level of [Ca(2+)](i) in the synaptosome. Treatment with nimodipine dramatically reduces the effects of brain damage induced by injection of PB.     

强啡肽对大鼠行为学和脊髓组织学改变的影响及受体机制

目的探明强啡肽(Dyn)对脊髓的损伤效应及其受体机制。方法观测大鼠鞘内注射DynA(1-13)或联合注射Kappa阿片受体拮抗剂nor-BNI或兴奋性氨基酸(EAA)的NMDA受体拮抗剂MK-801后的运动功能和脊髓病理学变化。结果注射30nmolDyn组3d时,Tarlov运动功能评分下降,脊髓前角神经元数目减少,GFAP阳性神经胶质细胞数轻度增生。14d时,Tarlov运动功能评分未恢复,神经胶质细胞增生明显。而鞘内联合注射100nmol nor-BNI、100nmol MK-801后3d时与单纯Dyn组结果相似,14d时Tarlov运动功能评分明显恢复,脊髓前角神经元数目较Dyn组多,GFAP阳性神经胶质细胞增生不明显,nor-BNI组与MK-801组间比较差异不显著。结论Dyn鞘内注射可使大鼠运动功能、脊髓组织损害,而nor-BNI或MK-801有对抗其损害作用。Dyn的病理作用是通过Kappa阿片受体和EAA的NMDA受体两种途径介导的。     

Effects of magnesium sulfate on traumatic brain edema in ats

OBJECTIVE: To investigate the effects of magnesium sulfate on traumatic brain edema and explore its possible mechanism. METHODS: Forty-eight Sprague-Dawley (SD) rats were randomly divided into three groups: Control, Trauma and Treatment groups. In Treatment group, magnesium sulfate was intraperitoneally administered immediately after the induction of brain trauma. At 24 h after trauma, total tissue water content and Na(+), K(+), Ca(2+), Mg(2+) contents were measured. Permeability of blood-brain barrier (BBB) was assessed quantitatively by Evans Blue (EB) dye technique. The pathological changes were also studied. RESULTS: Water, Na(+), Ca(2+) and EB contents in Treatment group were significantly lower than those in Trauma group (P<0.05). Results of light microscopy and electron microscopy confirmed that magnesium sulfate can attenuate traumatic brain injury and relieve BBB injury. CONCLUSIONS: Treatment with MgSO4 in the early stage can attenuate traumatic brain edema and prevent BBB injury.     

Prevention of reactive oxygen-induced endothelial cell injury by blocking its process.

Endothelial cell (EC) injury induced by reactive oxygen species (ROS) was investigated and effects of Ca(2+) channel blockers, agents which elevate intracellular cAMP levels ([cAMP](i)), and protein kinase inhibitors on H(2)O(2)-induced EC injury were analyzed using human umbilical vein EC cultures. Exposure to H(2)O(2) increased intracellular Ca(2+) levels and decreased [cAMP](i). Ca(2+) channel blockers, [cAMP](i)-elevating agents, and protein kinase inhibitors significantly inhibited H(2)O(2)-induced EC injury. Data suggest that H(2)O(2)-induced EC injury is mediated by extracellular Ca(2+) influx, intracellular cAMP efflux, and intracellular signaling, each of which is blocked by Ca(2+) channel blockers, [cAMP](i)-elevating agents, or protein kinase inhibitors. It is suggested that ischemia/reperfusion injury induced by ROS may be prevented by Ca(2+) channel blockers, [cAMP](i)-elevating agents, and protein kinase inhibitors.     

Nimodipine attenuates lipid peroxidation during the acute phase of head trauma in rats

Oxygen free radical-mediated lipid peroxidation is one of the major mechanisms of secondary damage in traumatic brain injury. We assessed the effects of nimodipine on lipid peroxidation 1 h after head trauma in rats. Nimodipine (1.5 μg/kg IV bolus injection) was given immediately after head trauma by either the carotid artery or the jugular vein. Placebo treated rats received saline by the same routes. Control rats received head trauma only. Sham-operated rats were the group without head trauma. Malondialdehyde (MDA), which is the end product of lipid peroxidation, was measured as an indicator of oxygen free radical formation in the brain tissue. The mean values for MDA in sham operated rats were 92.4±4.9 nanomoles/gram wet weight (nmol/gww) of brain tissue. In the control group, MDA content of the brain tissue was 120.8±9.4 nmol/gww. In placebo treated rats, the results were similar. In the groups receiving nimodipine via carotid artery or jugular vein, the mean values were 101.1±6.9 and 106.5±6.0 nmol/gww, respectively. These results indicate that nimodipine caused a significant decrease in lipid peroxidation when given in the acute phase of head trauma in rats. This occurred regardless of the route of injection. Received: 16 August 1999 / Accepted: 27 December 1999     

Effects of magnesium sulfate on traumatic brain edema in rats

svarietyofneuroprotectiveagentshavebeensynthesized .However ,besidessomeagentspresentlybeingevaluatedinclinicaltrails ,mostofthesecompoundshavelimitedclinicalusebecauseofneurotoxicityandbehavioralsideeffects .Recently ,severalstudiesdemonstratedthattraumaticinjurytothebraincausesadecreaseinmagnesiumconcentrationcorrelatedwithinjuryseverity .1Sincethen ,moreandmoreattentionhasbeen paidtoMgSO4 foritsneuroprotectiveeffects .Magnesiumsulfatehasbeenwidelyusedinclinicalpracticeforalmost 10 0 years.…     

Direct current reduces accumulation of Evans Blue albumin in full-thickness burns.

BACKGROUND: Application of direct current (DC) to a burn wound limits extension of the zone-of-stasis and reduces wound tissue edema. OBJECTIVE: To study the effects of DC on extravasation of plasma proteins after burn by using Evans blue (EB) as a marker of plasma albumin. MATERIALS AND METHODS: Male Sprague-Dawley rats with 20% total body surface area full-thickness scalds (100 degrees C/10 sec) were used as the experimental model. Burn wounds were treated with plain nylon, silver-nylon, silver-nylon and 40 microA DC, or no dressing. EB (30 mg/kg) was injected immediately or at variably delayed postburn (PB) times and accompanied by DC application at various time intervals PB. Tissue content of Evans blue was assessed at different times after injection of the dye or infliction of burn injury. RESULTS: Evans blue albumin (EBA) concentration in untreated burn wounds (307.7 microg/g tissue) was nine times greater than in unburned skin (36.5 microg/g tissue) at 48 hours PB. When animals received a DC and EB injection immediately PB, DC treatment reduced EBA concentration by 60% at any time point PB. When EB was injected immediately PB, or at variably delayed times PB, accompanied by DC immediately PB, or at variably delayed times PB, DC reduced EBA accumulation at all examined times PB by more the 50% (p < 0.001). CONCLUSION: EBA and edema fluid accumulation in burn wound change in concert after injury and show similar response to DC treatment.     

Intraplatelet calcium levels in patients with acute renal failure before and after the administration of loop diuretics.

BACKGROUND: Intracellular calcium [Ca](i) has been found to be elevated in hypoxic cells in vitro and in erythrocytes and lymphocytes from patients who are septic. Loop diuretics decrease [Ca](i) in platelets from patients with hypertension and in red blood cells from normal volunteers. We report the results of a study designed to measure [Ca](i) in platelets from patients with acute renal failure (ARF) before and after the administration of loop diuretics. METHODS: Sixteen healthy adults and seven patients with ARF were enrolled into the study. Intraplatelet calcium was measured using a fluorescent probe (quin2). Patients with ARF all received intravenous (i.v.) dopamine, 2 microg/kg body weight, and 20% mannitol, 100 ml every 6 h and, in double-blind manner, either torasemide, frusemide, or placebo, 3 mg/kg body weight i.v. every 6 h. Data from subjects given either frusemide or torasemide have been considered together and termed the diuretic group. RESULTS: Basal levels of [Ca](i) in platelets from patients with ARF were significantly higher than in controls (126.9 +/-3 5.7 nmol/l vs 85.7 +/- 22.2 nmol/l, P = 0.02), but were not affected by the administration of loop diuretic (126.9 +/- 35.7 nmol/l vs 165.9 +/- 49.7 nmol/l, P = 0.09, pre- vs post-diuretic). CONCLUSIONS: Intraplatelet calcium is raised in patients with ARF. Loop diuretics have no significant effect on intraplatelet calcium in these patients.     

Reduction of Edema and Infarction by Memantine and MK-801 After Focal Cerebral Ischaemia and Reperfusion in Rat

Summary  N-methyl-D-aspartate (NMDA) receptor antagonists have been found to be protective after cerebral ischemia. However most of these drugs have limited value as neuroprotectives in clinical therapy because of their side effects. Memantine is a noncompetitive NMDA receptor antagonist and it has been used for the treatment of various cerebral disorders with relatively few side effects. We investigated the beneficial effects of Memantine and compared its effect with MK-801 in a temporary focal cerebral ischemia model.  As cerebral ischemia model three hours middle cerebral artery occlusion (MCAO) with intraluminal thread and three hours reperfusion was used. 78 male Spraque-Dawley rats were divided into three groups as follows: Control (Saline), treatment 1 (MK-801), and treatment 2 (Memantine) groups. In the treated groups, 15 minutes after MCAO, MK-801 and Memantine were administered in amounts of 1 mg/kg and 10 mg/kg intraperitoneally respectively. After a 3 hour period of reperfusion, the animals were examined for neurological deficits and then killed. The following values were measured; cerebral water content, blood brain barrier (BBB) permeability at the core and periphery of the ischemic hemisphere and contralateral hemisphere and infarct volumes.  The severity of neurological deficit (p<0.001) and infarct volume (p<0.001) was reduced in both Memantine and MK-801 treated groups compared with saline treated groups. Memantine attenuated brain edema formation and BBB permeability at the periphery (p<0.01), MK-801 both at the core (p<0.05) and the periphery (p<0.01) of the ischemia.  These results demonstrated that the NMDA receptor antagonists Memantine and MK-801 were neuroprotective when given 15 min after MCAO in temporary focal cerebral ischemia.     

NMDA receptor activation contributes to a portion of the decreased mitochondrial membrane potential and elevated intracellular free calcium in strain-injured neurons

In our previous studies, we have shown that in vitro biaxial strain (stretch) injury of neurons in neuronal plus glial cultures increases intracellular free calcium ([Ca(2+)](i)) and decreases mitochondrial membrane potential (deltapsi(m)). The goal of this study was to determine whether strain injury, without the addition of exogenous agents, causes glutamate release, and whether NMDA receptor antagonists affect the post-strain injury rise in [Ca(2+)](i) and decrease in deltapsi(m). [Ca(2+)](i) and deltapsi(m) were measured using the fluorescent indicators fura-2 AM and rhodamine-1,2,3 (rh123). Strain injury of neuronal plus glial cultures caused an immediate 100-200 nM elevation in neuronal [Ca(2+)]i and a decline in neuronal deltapsi(m) by 15 min post-injury. Pretreatment with the NMDA receptor antagonist MK-801 (10 microM) attenuated the [Ca(2+)](i) elevation after mild, but not moderate and severe injury. MK-801 pretreatment reduced the decline in deltapsi(m) after mild and moderate, but not after severe injury. The NMDA receptor antagonist D-2-amino-5-phosphonopentanoic acid (APV; 100 microM) had effects similar to MK-801. Simultaneous measurement of [Ca(2+)](i) and deltapsi(m) demonstrated a significant correlation and a temporal relationship between [Ca(2+)](i) elevation and depression of deltapsi(m). We conclude that NMDA receptor stimulation contributes to some of the changes in [Ca(2+)](i) and deltapsi(m) after less severe strain injury. However, after more pronounced injury other mechanisms appear to be more involved.     

Autoradiographic analysis of 3H-MK-801 (dizocilpine) in vivo uptake and in vitro binding after focal cerebral ischemia in the rat.

The clinical utility of N-methyl-D-aspartate (NMDA) receptor antagonists is now being assessed in ischemic brain injury in humans. The uptake and retention of NMDA receptor antagonists in ischemic tissue will influence the design of clinical trials. The effects of permanent occlusion of the middle cerebral artery, induced 15 minutes prior to isotope administration, on the uptake of 3H-MK-801 (dizocilpine) have been assessed in the rat with quantitative autoradiography. In a group of three rats at 15 minutes after the intravenous administration of 3H-MK-801, the level (mean +/- standard error of the mean) of isotopic tracer in the ischemic cortex and striatum was markedly less than that in the contralateral hemisphere (ipsilateral vs. contralateral caudate nucleus: 22 +/- 4 vs. 84 +/- 11 pmol/gm, p less than 0.01). In contrast, in a group of five rats at 60 minutes after the intravenous administration of 3H-MK-801, the level of isotopic tracer in the ischemic cortex and striatum was greater than that in the contralateral hemisphere (ipsilateral vs. contralateral caudate nucleus: 52 +/- 8 vs. 32 +/- 4 pmol/gm, p less than 0.05). There were no significant alterations in the specific binding of 3H-MK-801 in vitro in ischemic tissue at equivalent times. The early uptake of 3H-MK-801 into the central nervous system is dominated by the level of cerebral blood flow, whereas at later times after administration enhancement of MK-801 binding by elevated extracellular glutamate concentrations appears to be more important in determining the level of the drug in ischemic tissue.     

An experimental study on the occurrence of brain edema after retrograde cerebral perfusion

To assess the safety of retrograde cerebral perfusion, the occurrence of brain edema after this procedure was investigated. Twenty-eight adult mongrel dogs were divided into three groups that underwent the following treatments: antegrade perfusion (group 1, n=9); retrograde perfusion alone (group 2, n=11); or tetrograde perfusion with drugs (manuitol, thiopental sodium, and methylprednisolone; group 3, n=8). After 90 minutes of cerebral perfusion at 20°C of the pharyngeal temperature, evans blue (EB) was administered to check for disruptions of the blood-brain-barrier (BBB) and brain tissue water content was measured. Intracranial pressure after cerebral perfusion was markedly higher in group 2 than in group 1 (26.4 ± 9.4 vs. 11.2 ± 3.6 mmHg), and brain tissue water content was also significantly higher in group 2 than in group 1 (80.7 ± 2.0 vs. 77.8 ± 0.9%). these data suggested that brain edema was more prominent after retrograde perfusion than after antegrade perfusion. The extent of EB to brain tissue was greater in group 2 than in group 1 (169.8 ± 97.7 vs. 54.7 ± 31.5 μg/dl). The BBB was highly disrupted in group 2 and vasogenic edema appeared after retrograde cerebral perfusion. Maximum intracranial pressure, brain tissue water content and EB concentration were significantly lower in group 3 than in group 2, and did not differ significantly between group 3 and 1. Administration of pharmacologic agents suppressed edema formation and extravasation of EB. We conclude that 90 minutes of retrograde cerebral perfusion at 20°C of the pharyngeal temperature causes brain edema and disrupts the BBB in a manner different from that associated with antegrade perfusion. Mannitol, thiopental sodium, and methylprednisolone prevent these phenomena, indicating that pharmacologic intervention may improve the safety of retrograde cerebral perfusion.     

Role of norepinephrine and excitatory amino acids in edema of the spinal cord after experimental compression injury in rats

The role of norepinephrine and excitatory amino acids in edema of the spinal cord after an acute experimental compression injury was studied in rats. Control rats received the compression injury only. Intraspinal norepinephrine was depleted in one rat group by injection of 6-hydroxydopamine (6-OHDA) into the subarachnoid space to selectively destroy catecholamine neurons and in a third group MK-801 was administered intravenously to block receptors for N-methyl-d-aspartate (NMDA), an excitatory amino acid. Recovery from motor paralysis and suppression of edema of the spinal cord were then compared in the three groups. Significant recovery from motor paralysis was found 12 h after injury in the 6-OHDA-treated rats, compared with the controls, and 24 h after injury in the MK-801-treated rats. Edema of the spinal cord was significantly suppressed for up to 24 h after injury in the 6-OHDA-treated rats. The MK-801-treated rats showed no significant suppression of the edema until 24 h after the spinal cord injury. It was concluded that norepinephrine is primarily involved in the formation of vasogenic edemas, which develop in the early stages after an injury, whereas excitatory amino acids affect the formation of cytotoxic edemas, which develop at a relatively later stage. Received for publication on March 26, 1997; accepted on July 8, 1997     

Protective Effect of the N-Methyl-D-Aspartate Receptor Antagonists, MK-801 and CPP on Cold-Induced Brain Oedema

Summary  Cold injury model in rat was used to determine the effect of treatment with the competitive NMDA antagonists CPP and the non-competitive NMDA antagonist MK-801 in cerebral oedema. MK-801 was applied in doses of 1 mg/kg and CPP of 10 mg/kg, 15 min. after injury. Control animals received 1 ml saline at the same time interval after injury. Tissue samples from the core and periphery of the lesion of the injured hemisphere and from the symmetrical location of the undamaged contralateral hemisphere were removed 24 hours after injury. Blood brain barrier permeability, brain water content and tissue specific gravity values were determined. MK-801 was found beneficial for reducing the oedema and restore the blood brain barrier permeability at the penumbral zone of the lesion, whereas both MK-801 and CPP were found ineffective for prevention of oedema accumulation at the core of the lesion.     

Intracellular free calcium accumulation in ferret vascular smooth muscle during crystalloid and blood cardioplegic infusions.

OBJECTIVE: The effects of magnesium- and potassium-based crystalloid and blood-containing cardioplegic solutions on coronary smooth muscle intracellular free calcium ([Ca2+]i) accumulation and microvascular contractile function were examined. METHODS: Isolated ferret hearts were subjected to hyperkalemic (25 mmol/L K+) blood cardioplegic infusion, hypermagnesemic (25 mmol/L Mg2+, K+-free) crystalloid cardioplegic infusion, or hyperkalemic crystalloid cardioplegic infusion for 1 hour. Coronary arterioles were isolated, cannulated, and loaded with fura 2. Reactivity and [Ca2+]i were assessed with videomicroscopy. [Ca2+]i was measured at baseline and after application of 50 mmol/L KCl. In addition, [Ca2+]i and vascular contraction were measured during exposure to Mg2+ and K+ cardioplegic solution at both 4 degrees C and 37 degrees C. RESULTS: From a baseline [Ca2+]i of 177 +/- 52 nmol/L, K+ cardioplegic infusion (302 +/- 80 nmol/L potassium) markedly increased [Ca2+]i, whereas blood cardioplegic infusion (214 +/- 53 nmol/L) and Mg2+ cardioplegic infusion (180 +/- 42 nmol/L) did not alter [Ca2+]i. Although a difference between groups in percentage contraction after application of 50 mmol/L KCl was not observed, [Ca2+]i increased significantly more in vessels in the control group (764 +/- 327 nmol/L) and the K+ crystalloid cardioplegic infusion group (698 +/- 215 nmol/L) than in vessels in the blood cardioplegic infusion group (402 +/- 45 nmol/L) and the Mg2+ cardioplegic infusion group (389 +/- 80 nmol/L). Mg2+ cardioplegic solution induced no microvascular contraction at either 4 degrees C or 37 degrees C, nor was an increase in [Ca2+]i observed. K+ cardioplegic solution induced microvascular contraction at 37 degrees C but not at 4 degrees C; it increased [Ca2+]i at both 4 degrees C and 37 degrees C. CONCLUSION: An Mg2+-based cardioplegic solution, or appropriate Mg2+ or blood supplementation of a K+ crystalloid cardioplegic solution, may decrease the accumulation of [Ca2+]i in the vascular smooth muscle during ischemic arrest.     

Effect of acute calcium influx after mechanical stretch injury in vitro on the viability of hippocampal neurons

We use a new in vitro model to examine the effect of mechanical deformation on neurons. We examined acute changes in cytosolic calcium concentrations ([Ca(2+)](i)) caused by a rapid stretch of cultured hippocampal neurons, using mechanical loading conditions that mimic brain deformations during trauma. We found that stretch-injury of neurons induces a strain-dependent increase in [Ca(2+)](i). Remarkably, the extent of this calcium response exceeded the levels initiated by chemical toxicity with NMDA (100 microM) or glutamate (5 mM) exposure. Propidium iodide labeling at 24 h following stretch showed neuronal death occurred only at the most severe level of mechanical injury. Although NMDA-induced toxicity could be inhibited in calcium free media or by treatment with MK-801, stretch-induced neuronal death was not similarly reduced with either treatment. Unexpectedly, reduction of the acute stretch-induced calcium transient with calcium-free media or MK-801 resulted in an increase in neuronal death at lower stretch levels. These data suggest that mechanical stretch can initiate calcium influx in hippocampal neurons, but substantially modulating the early calcium flux from the extracellular space or through the NMDA channel does not provide an effective means for improving neuronal survival.     

Regulation of mesangial cell apoptosis and proliferation by intracellular Ca(2+) signals

BACKGROUND: In inflammatory glomerular diseases, proliferation, as well as apoptosis of mesangial cells (MCs), has been shown histomorphologically. Both processes may regulate the cellular content of the mesangium by closely influencing each other. In the present study, we examined whether the cytoplasmic free Ca(2+) concentration [Ca(2+)](i) is involved as a key second messenger in the regulation of proliferative and apoptotic events. METHODS: Thapsigargin, an inhibitor of the endoplasmic Ca(2+)-Mg(2+)-ATPase, was used as a test substance to investigate the role of [Ca(2+)](i) in signaling MC apoptosis and growth in vitro. Apoptosis was determined by nuclear chromatin staining with Hoechst 33258, by a [3H]-thymidine-based DNA fragmentation assay or by flow cytometry detecting binding of FITC-conjugated annexin V. Proliferation was measured by [3H]-thymidine incorporation into acid-precipitable material and corroborated by cell counting. RESULTS: Thapsigargin significantly induced apoptosis and inhibited proliferation dose dependently in nanomolar concentrations without evoking necrotic damage when administered not longer than 12 hours. Significant apoptosis was measurable after a six-hour treatment of MCs with thapsigargin. Determination of [Ca(2+)](i) by fura-2-dependent spectrofluorometry showed that thapsigargin was able to induce prolonged [Ca(2+)](i) rises that could be prevented by preincubation with the intracellular Ca(2+) chelator 1, 2-bis(2-aminophenoxy)-ethane-N,N,N', N'-tetra-acetic acid (BAPTA) acetomethyl ester (AM). BAPTA had no influence on MC viability but reversed thapsigargin-induced apoptosis to control levels. After thapsigargin treatment (100 nmol/L, 12 hours), apoptotic MCs had a significantly higher [Ca(2+)](i) of 251 +/- 25 nmol/L (N = 41) as compared with MCs that were not or not yet apoptotic ([Ca(2+)](i) of 116 +/- 20 nmol/L, N = 26, P < 0,05). Platelet-derived growth factor (PDGF), a well-characterized growth factor for MCs, reversed the effects of thapsigargin on proliferation and apoptosis in a similar fashion as BAPTA. PDGF acutely stimulated increases of [Ca2+]i but abolished thapsigargin-dependent, but not angiotensin II- or ATP-induced Ca(2+) rises when administered during a 12-hour preincubation. CONCLUSIONS: Our data suggest that a sustained increase of [Ca(2+)](i) may serve as a signal to trigger MC apoptosis. Growth factors such as PDGF can abolish apoptosis induced by elevations of [Ca(2+)](i) by altering intracellular Ca(2+) signaling.     

Experimental neoplastic spinal cord compression: effect of ketamine and MK-801 on edema and prostaglandins

Excitotoxin-induced neural tissue damage is mediated through specific receptors. We studied the in vivo effect of two selective N-methyl-D-aspartate receptor antagonists on the compressed spinal cord segments of rats harboring a thoracolumbar epidural tumor. The effect of a single intramuscular treatment with either MK-801 (3 mg/kg) or ketamine (110 mg/kg) given at the onset of paraplegia was evaluated 30 hours later. In saline-treated control animals, significant increases in water content, prostaglandin E2, and 6-keto-prostaglandin F1 alpha were evident. Treatment with either agent resulted in a normal water content in the compressed segments but had no effect on prostaglandin synthesis. Evaluation of the effect of treatment on the course of the disease required dose reduction by 45% for ketamine and by 30% for MK-801, to avoid the excessive sedative effect. Treatment was started at the first appearance of neurological dysfunction (Grade 1) and continued to paraplegia (Grade 5). The mean time interval between Grades 1 and 5 was 2.1 +/- 0.3 days in saline-treated control animals, and it was not significantly altered by either ketamine or MK-801. Our study indicates that in the end stage of epidural compression, when ischemia is present, excitotoxins probably participate in the evolution of a cytotoxic edema. It is suggested that treatment initiated at the onset of paraplegia may still reduce the cytotoxic edema, but its potential clinical value requires further investigations.     

尼莫地平复合7.5%高渗盐水对七氟醚诱导老龄大鼠海马神经元凋亡的影响

目的探讨尼莫地平复合7.5%高渗盐水对七氟醚诱导老龄大鼠海马神经元凋亡的影响。方法健康雄性Wistar大鼠96只,18月龄,体重450~500g,采用随机数字表法将其分为四组(n=24):对照组(C组)、尼莫地平组(N组)、高渗盐水组(HS组)和尼莫地平+高渗盐水组(NHS组)。C组腹腔和尾静脉注射生理盐水;N组腹腔注射尼莫地平1 mg/kg,尾静脉注射生理盐水;HS组尾静脉注射7.5%高渗盐水4 ml/kg,腹腔注射生理盐水;NHS组腹腔注射尼莫地平1mg/kg,尾静脉注射7.5%高渗盐水4ml/kg。30min后四组大鼠吸入3%七氟醚2h。于麻醉前1d、麻醉后1、3、7d行Morris水迷宫实验,实验结束后每组随机处死8只大鼠,取海马组织,采用流式细胞术测定海马神经元凋亡率和胞浆钙离子浓度;采用RT-PCR法测定海马Bcl-2、Bax的mRNA表达量。结果与C组比较,N、HS、NHS组大鼠麻醉后1、3、7d逃避潜伏期明显缩短,穿越原平台次数明显增加,麻醉后1、7d海马神经元凋亡率和胞浆钙离子浓度明显减低,Bcl-2 mRNA表达量明显上调,Bax mRNA表达量明显下调,Bax/Bcl-2比值明显降低(P0.05);与NHS组比较,N和HS组大鼠麻醉后1、3、7d逃避潜伏期明显延长,穿越原平台次数明显减少,麻醉后1、7d海马神经元凋亡率和胞浆钙离子浓度明显增高,Bcl-2 mRNA表达量明显下调,Bax mRNA表达量明显上调,Bax/Bcl-2比值明显升高(P0.05)。结论尼莫地平复合7.5%高渗盐水可抑制钙超载,降低七氟醚诱导老龄大鼠海马神经元凋亡率,且其作用优于单独给药。     

Cytosolic ionized calcium concentration in isolated chondrocytes from each zone of the growth plate

In isolated chondrocytes from the growth plate, there is an increase in both the cytosolic ionized calcium concentration and in total cell calcium content as the cells approach the mineralization front. The reserve zone chondrocytes have a cytosolic ionized calcium concentration, [Ca2+]i, of 124 +/- 23 nM and a total cell calcium content, CaT, of 12.8 +/- 6.8 nmol/mg cell protein. Proliferative zone chondrocytes have a [Ca2+]i of 172 +/- 29 nM and a CaT of 16.1 +/- 11.8 nmol/mg cell protein. Hypertrophic zone chondrocytes have a [Ca2+]i of 273 +/- 49 nM and a CaT of 35.8 +/- 16 nmol/mg protein. Chondrocytes isolated from the entire growth plate have a [Ca2+]i of 132 +/- 29 nM and a CaT of 13.2 +/- 2.5 nmol/mg cell protein. Chondrocytes isolated from noncalcifying hyaline cartilage have a [Ca2+]i of 85 +/- 10 nM and a CaT of 11.5 +/- 1.4 nmol/mg cell protein. There appears to be a correlation between intracellular calcium accumulation, an increase in the intracellular ionized calcium concentration, and the process of cartilage matrix mineralization.