Ranolazine, an inhibitor of the late sodium channel current, reduces postischemic myocardial dysfunction in the rabbit

Ranolazine is a selective inhibitor of the late sodium current relative to peak sodium channel current, and via this mechanism, it may decrease sodium-dependent intracellular calcium overload during ischemia and reperfusion. Ranolazine reduces the frequency of angina attacks, but there is little information on its effects on myocardial stunning after short-term ischemia. The objective of this study was to test the effects of ranolazine on left ventricular (LV) function and myocardial stunning after ischemia/reperfusion in rabbits. Myocardial stunning was induced in rabbits by 15 minutes of coronary artery occlusion (CAO) followed by 3 hours reperfusion. Ten minutes before CAO, rabbits were randomly assigned to vehicle (n = 15) or ranolazine (2 mg/kg bolus plus 60 microg/kg/min infusion, IV, n = 15). Myocardial stunning was assessed by LV 2-dimensional echocardiography using, as a marker of severity, ischemic free-wall fractional thickening (FWft; systolic wall thickness - diastolic wall thickness/diastolic wall thickness). Regional ejection fraction (EF) was also assessed. During CAO, FWft was depressed in both groups, indicating an ischemic insult (FWft was reduced from 0.62 +/- 0.05 at baseline to 0.10 +/- 0.04 in vehicle and from 0.73 +/- 0.05 to 0.26 +/- 0.07 in ranolazine, P < 0.05, ranolazine vs vehicle). After reperfusion, previously ischemic myocardium remained stunned; however, FWft recovered significantly better in ranolazine (0.51 +/- 0.05) than in vehicle (0.35 +/- 0.04, P = .027). Baseline EF was 0.65 +/- 0.02 in the ranolazine and 0.68 +/- 0.02 in vehicle (P = ns). During CAO, EF was reduced by 36% +/- 6% in vehicle versus only 20% +/- 6% in ranolazine (P < .05). At the end of reperfusion, EF remained depressed in both groups, but the reduction in the vehicle group (25% +/- 5%) was significantly worse than in ranolazine (9% +/- 4%, P = .017). Improvement in function was independent of necrosis (negligible) or differences in hemodynamics (no differences between groups). Ranolazine treatment reduced myocardial stunning following brief ischemia/reperfusion suggesting that inhibiting the late sodium channel current may be a novel approach to treating stunning independent of effects on hemodynamics.     

Pretreament with repeated electroacupuncture induced neuroprotection against spinal cord ischemiareperfusion injury in rabbits

AIM:To investigate whether pretreatment with repeated electroacupuncture (EA) could induce ischemic tolerance against transient spinal cord ischemia in rabbits.METHODS:24male New Zealand white rabbits were randomly assigned to 3 groups(n=8 each),animals in the control group received no treatment;animals in the SP and EA group received sodium pentobarbitone 30mg/kg each day for 5 days;animals in EA group were also received electroacupuncture at the Zusanli acupoint 30min a day for 5days.24hours after the last treatment,spinal cord ischemia was induced by an infrarenal aortic occlusion for 20min.Hind-limb motor function was determined with the Tarlov criteria at 4,8,12,24 and 48h after reperfusion.All animals were sacrificed at 48h after reperfusion and the spinal cords(I5) were remoed immediately for histopathologic study.RESULTS:The neurologic outcome and histopathology(48h) in the EA group were significantly better than the control group(P=0.006).CONCLUSION:Pre-ischemic treatment with electroacupuncture significantly reduces spinal cord ischemia-reperfusion injury in rabbits.     

重复电针预处理对兔脊髓缺血再灌注损伤的保护作用

AIM: To investigate whether pretnatment with repeated electroacupuncture (EA) could induce ischemic tolerance against transient spinal cord ischemia in rabbits. METHODS: 24 male New Zealand white rabbits were randomly assigned to 3 groups(n = 8 each), animals in the control group received no treatment; animals in the SP and EA group received sodium pentobarbitone 30 mg/kg each day for 5 days; animals in EA group were also received electroacupuncture at the Zusanli acupoint 30 min a day for 5 days. 24 hours after the last treatment, spinal cord ischemia was induced by an infrarenal aortic occlusion for 20 min. Hind-limb motor function was determined with the Tarlov criteria at 4,8,12,24 and 48 h after reperfusion. All animals were sacrificed at 48h after reperfusion and the spinal cords(L5) were removed immediately for histopathologic study. RESULTS: The neurologic outcome and histopathology (48 h) in the EA group were significantly better than the control group( P = 0. 006) . CONCLUSION: Pre-ischemic tr     

纳洛酮对重复电针预处理诱导脊髓缺血耐受作用的影响

目的 :研究阿片肽在电针重复预处理诱导脊髓缺血耐受中的作用。方法 :4 0只雄性新西兰大白兔随机分成 5组 (n=8) :对照组、戊巴比妥钠组、纳洛酮组、电针预处理组和纳洛酮 +电针预处理组。对照组未行任何处理 ;戊巴比妥钠组每日静脉给予戊巴比妥钠 30 m g/ kg,连续 5 d;纳洛酮组每日静脉给予纳洛酮 0 .3mg/ kg,连续 5 d;电针预处理组每日在戊巴比妥钠 30 m g/ kg麻醉下 ,电针刺激双侧委中穴 6 0 min/ d,连续 5 d;纳洛酮 +电针预处理组预处理前 30 m in静脉注射纳洛酮 0 .3mg/ kg,余同预处理组。最后一次预处理后 2 4 h阻闭肾下腹主动脉 2 0 min,制备兔脊髓缺血模型 ;再灌注后 4 h、8h、12 h、2 4 h和 4 8h分别对动物后肢运动功能进行评分 ;再灌注 4 8h后深麻醉下处死动物取脊髓 (L 5～ L 7) ,制作标本并行组织病理学观察。结果 :所有动物都存活 ,再灌注 4 8h后电针预处理组动物后肢运动功能评分及脊髓前角运动神经元计数均明显高于纳洛酮 +电针预处理组 (P均 <0 .0 1) ,对照组、戊巴比妥钠组、纳洛酮组及纳洛酮 +电针预处理组间后肢运动功能评分及脊髓前角运动神经元计数均无显著性差异 (P均 >0 .0 5 )。结论 :重复电针预处理对兔脊髓缺血再灌注损伤的保护作用可被纳洛酮阻断 ,提示阿片肽参与了电针预处     

不同穴位重复电针预处理诱导兔脊髓缺血耐受效果的对比

目的:比较不同穴位电针预处理对兔脊髓缺血再灌注损伤保护作用的效果,为临床提供最佳的预处理方案。方法:32只雄性新西兰大白兔随机数字表法分成4组(各组n=8),即对照组、戊巴比妥钠组、委中穴组及足三里穴组。对照组静脉给予生理盐水1mL/kg,连续5d;戊巴比妥钠组静脉给予戊巴比妥钠30mg/kg,连续5d;委中穴和足三里穴组每天在戊巴比妥钠(30mg/kg)麻醉下,电针分别刺激委中穴和足三里穴60min/d,连续5d。最后一次预处理后24h,夹闭肾下腹主动脉20min,制作兔脊髓缺血模型;再灌注后4,8,12,24和48h分别对动物后肢运动功能评分;再灌注48h后,深麻醉下处死动物取脊髓(L5～7),制作标本行组织病理学观察。结果:所有动物均存活,再灌注后48h电针预处理委中穴和足三里穴组后肢运动功能评分及脊髓前角运动神经元计数均明显高于对照组(P=0.001);足三里组后肢运动功能评分和脊髓前角运动神经元计数明显低于委中穴组(P=0.001);对照组与戊巴比妥钠组相比,后肢运动功能评分及脊髓前角神经元计数无显著性差别(P=1.0和P=0.873)。结论:电针预处理对兔脊髓缺血再灌注损伤有显著的保护作用,且刺激委中穴优于刺激足三里穴的效果。     

Evidence for an essential role of reactive oxygen species in the genesis of late preconditioning against myocardial stunning in conscious pigs.

Conscious pigs underwent a sequence of 10 2-min coronary occlusions, each separated by 2 min of reperfusion, for three consecutive days (days 1, 2, and 3). On day 1, pigs received an i.v. infusion of a combination of antioxidants (superoxide dismutase, catalase, and N-2 mercaptopropionyl glycine; group II, n = 9), nisoldipine (group III, n = 6), or vehicle (group I [controls], n = 9). In the control group, systolic wall thickening (WTh) in the ischemic-reperfused region on day 1 remained significantly depressed for 4 h after the 10th reperfusion, indicating myocardial "stunning." On days 2 and 3, however, the recovery of WTh improved markedly, so that the total deficit of WTh decreased by 53% on day 2 and 56% on day 3 compared with day 1 (P < 0.01), indicating the development of a powerful cardioprotective response (late preconditioning against stunning). In the anti-oxidant-treated group, the total deficit of WTh on day 1 was 54% less than in the control group (P < 0.01). On day 2, the total deficit of WTh was 85% greater than that observed on day 1 and similar to that observed on day 1 in the control group. On day 3, the total deficit of WTh was 58% less than that noted on day 2 (P < 0.01). In the nisoldipine-treated group, the total deficit of WTh on day 1 was 53% less than that noted in controls (P < 0.01). On days 2 and 3, the total deficit of WTh was similar to the corresponding values in the control group. These results demonstrate that: (a) in the conscious pig, antioxidant therapy completely blocks the development of late preconditioning against stunning, indicating that the production of reactive oxygen species (ROS) on day 1 is the mechanism whereby ischemia induces the protective response observed on day 2; (b) antioxidant therapy markedly attenuates myocardial stunning on day 1, indicating that ROS play an important pathogenetic role in postischemic dysfunction in the porcine heart despite the lack of xanthine oxidase; (c) although the administration of a calcium-channel antagonist (nisoldipine) is as effective as antioxidant therapy in attenuating myocardial stunning on day 1, it has no effect on late preconditioning on day 2, indicating that the ability of antioxidants to block late preconditioning is not a nonspecific result of the mitigation of postischemic dysfunction on day 1. Generation of ROS during reperfusion is generally viewed as a deleterious process. Our finding that ROS contribute to the genesis of myocardial stunning but, at the same time, trigger the development of late preconditioning against stunning supports a complex pathophysiological paradigm, in which ROS play an immediate injurious role (as mediators of stunning) followed by a useful function (as mediators of subsequent preconditioning).     

Late preconditioning against myocardial stunning. An endogenous protective mechanism that confers resistance to postischemic dysfunction 24 h after brief ischemia in conscious pigs.

Conscious pigs underwent a sequence of 10 2-min coronary occlusions, each separated by 2 min of reperfusion, for three consecutive days (days 1, 2, and 3 of stage I). The recovery of systolic wall thickening (WTh) after the 10th reperfusion was markedly improved on days 2 and 3 compared with day 1, indicating that the myocardium had become preconditioned against "stunning." 10 d after stage I, pigs underwent again a sequence of 10 2-min coronary occlusions for two consecutive days (days 1 and 2 of stage II). On day 1 of stage II, the recovery of WTh after the 10th reperfusion was similar to that noted on day 1 of stage I; on day 2 of stage II, however, the recovery of WTh was again markedly improved compared with day 1. Blockade of adenosine receptors with 8-p-sulfophenyl theophylline failed to prevent the development of preconditioning against stunning. Northern blot analysis demonstrated an increase in heat stress protein (HSP) 70 mRNA 2 h after the preconditioning ischemia; at this same time point, immunohistochemical analysis revealed a concentration of HSP70 in the nucleus and an overall increase in staining for HSP70. 24 h after the preconditioning ischemia, Western dot blot analysis demonstrated an increase in HSP70. This study indicates the existence of a new, previously unrecognized cardioprotective phenomenon. The results demonstrate that a brief ischemic stress induces a powerful, long-lasting (at least 48 h) adaptive response that renders the myocardium relatively resistant to stunning 24 h later (late preconditioning against stunning). This adaptive response disappears within 10 d after the last ischemic stress but can be reinduced by another ischemic stress. Unlike early and late preconditioning against infarction, late preconditioning against stunning is not blocked by adenosine receptor antagonists, and therefore appears to involve a mechanism different from that of other forms of preconditioning currently known. The increase in myocardial HSP70 is compatible with, but does not prove, a role of HSPs in the pathogenesis of this phenomenon.     

Effect of calcium entry blocker nitrendipine on renal function after renal vascular occlusion

The ability of the Ca entry blocker nitrendipine to improve postischemic renal function was studied in nine groups (n = 70) of rats. After anesthesia, nitrendipine was administered for 15 min through the femoral vein. The dose administered depended on the group. Group 1 (n = 7), the control, received only 0.9% NaCl, group 2 (n = 12) 0.25 mg/kg; group 3 (n = 10) 0.50 mg/kg; group 4 (n = 8) 0.75 mg/kg; group 5 (n = 6) 1.00 mg/kg; group 6 (n = 7) 1.50 mg/kg; group 7 (n = 7) 2.00 mg/kg; group 8 (n = 6) 2.50 mg/kg; and group 9 (n = 7) 3.00 mg/kg. After the administration of nitrendipine, the kidneys were rendered ischemic for one hour by cross-clamping the renal vessels. Comparison of 24-h creatinine clearances for 72 h after reversal of ischemia demonstrated that nitrendipine was capable of providing a degree of protection against renal ischemia and the protective effect was dose dependent (p less than .05).     

Hypoxia alters the subcellular distribution of protein kinase C isoforms in neonatal rat ventricular myocytes.

Cardiac myocytes coexpress multiple protein kinase C (PKC) isoforms which likely play distinct roles in signaling pathways leading to changes in contractility, hypertrophy, and ischemic preconditioning. Although PKC has been reported to be activated during myocardial ischemia, the effect of ischemia/hypoxia on individual PKC isoforms has not been determined. This study examines the effect of hypoxia on the subcellular distribution of individual PKC isoforms in cultured neonatal rat ventricular myocytes. Hypoxia induces the redistribution of PKC alpha and PKC epsilon from the soluble to the particulate compartment. This effect (which is presumed to represent activation of PKC alpha and PKC epsilon) is detectable by 1 h, sustained for up to 24 h, and reversible within 1 h of reoxygenation. Inhibition of phospholipase C with tricyclodecan-9-yl-xanthogenate (D609) prevents the hypoxia-induced redistribution of PKC alpha and PKC epsilon, whereas chelation of intracellular calcium with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) blocks the redistribution of PKC alpha, but not PKC epsilon; D609 and BAPTA do not influence the partitioning of PKC alpha and PKC epsilon in normoxic myocytes. Hypoxia, in contrast, decreases the membrane association of PKC delta via a mechanism that is distinct from the hypoxia-induced translocation/activation of PKC alpha/PKC epsilon, since the response is slower in onset, slowly reversible upon reoxygenation, and not blocked by D609 or BAPTA. The hypoxia-induced shift of PKC delta to the soluble compartment does not prevent subsequent 4-beta phorbol 12-myristate-13-acetate-dependent translocation/activation of PKC delta. Hypoxia does not alter the abundance of any PKC isoform nor does it alter the subcellular distribution of PKC lambda. The selective hypoxia-induced activation of PKC isoforms through a pathway involving phospholipase C (PKC alpha/PKC epsilon) and intracellular calcium (PKC alpha) may critically influence cardiac myocyte contractility, gene expression, and/or tolerance to ischemia.     

兔心脏缺血再灌注损伤后重组水蛭素的保护作用及其机制

背景重组水蛭素能否通过抑制白细胞浸润来拮抗心肌缺血/再灌注(ischemia/reperfusion,IR)损伤,从而起到对心肌的保护作用?目的观察重组水蛭素对缺血心肌内白细胞浸润的影响,进一步探讨重组水蛭素对心肌保护的作用机制.设计随机对照的实验研究.地点、材料和干预本实验在第四军医大学唐都医院心血管病实验室完成.选取24只日本大耳白兔随机分为2组,每组12只.IR组;心脏左冠状动脉前降支IR动物模型,缺血45 min、再灌注120 min,再灌注前后静脉应用生理盐水;重组水蛭素组缺血45 min、再灌注120 min,再灌注前15 min静注重组水蛭素(1 mg/kg),再灌注时继以持续静滴重组水蛭素[1 mg/(kg·h)]120 min.主要观察指标心肌梗死范围及缺血心肌内白细胞浸润的变化.结果重组水蛭素组的心肌梗死范围为(11.7±2.4)%,与缺血再灌注组的(21.2±5.3)%比较,梗死范围明显缩小(t=7.436,P＜0.01).缺血再灌注组的髓过氧化物酶(myeloperoxidase,MPO)活性为(56.01±3.83)nkat/g,重组水蛭素组(35.51±1.67)nkat/g.重组水蛭素组缺血心肌内白细胞聚集较缺血再灌注组显著减少(t=3.935,P＜0.05).结论重组水蛭素能够抑制再灌注期缺血心肌内白细胞浸润,拮抗心肌IR损伤.     

氯胺酮预处理对兔脊髓缺血性损伤的保护作用

目的观察氯胺酮预处理对兔脊髓缺血再灌注损伤的保护作用。方法24只日本大白兔随机分为假手术组(A组)、缺血再灌注组(B组)和氯胺酮预处理组(C组),各组均为8只。A组不阻断主动脉,B组左肾下阻断主动脉45min,C组左肾下阻断主动脉前10min及开放后即刻静推氯胺酮30mg·kg-1。术后进行后肢神经功能评分和针电极肌电图(EMG)的描记及脊髓形态学改变的观察。结果B组分别同A、C组相比,神经功能和病理学评分均显著性偏低(P<0.01),且同C组相比,后肢EMG亦有显著性病理改变(P<0.01)。C组1只动物发生迟发性瘫痪。结论氯胺酮预处理对家兔脊髓缺血再灌注损伤具有一定的保护作用。     

Hyperbaric oxygen therapy given 30 minutes after spinal cord ischemia attenuates selective motor neuron death in rabbits

OBJECTIVE: Spinal cord ischemia sometimes causes paraplegia because the spinal motor neuron cells are vulnerable to ischemia. Although various protective remedies for spinal cord injury have been reported, there have been few established clinical methods. Although hyperbaric oxygen (HBO) has been used clinically as a treatment for ischemia, the reason for its effectiveness is still uncertain because sufficient experimental data are lacking. DESIGN: Prospective, randomized, controlled study. SETTING: Experimental animal research laboratory in a university research center. SUBJECTS: Twenty-three Japanese white rabbits, weighing 2-3 kg. INTERVENTIONS: A modified rabbit spinal cord ischemia model of infrarenal aortic occlusion for 15 mins was employed. Rabbits were randomly assigned to four groups; the rabbits in group A did not undergo ischemic insults (n = 5). The rabbits in groups B and C underwent ischemic insult for 15 mins, followed by 1 hr of HBO treatment at 3 atm absolute with 100% oxygen at 30 mins (n = 6) or 6 hrs (n = 7) after reperfusion, respectively. The rabbits in group D underwent ischemic insult for 15 mins without HBO treatment (n = 5). MEASUREMENTS AND MAIN RESULTS: We observed neurologic functions for 14 days. The sections of the spinal cords were stained with hematoxylin and eosin, and the number of spinal motor neurons in ventral region was counted by light microscopy. All rabbits in groups A and B could stand, whereas all rabbits in groups C and D showed irreversible paraplegia on days 2 and 14 after reperfusion. Spinal motor neurons in ventral gray matter in groups C and D decreased significantly compared with those in groups A and B. CONCLUSIONS: HBO therapy shortly after ischemic insult had protective effects against ischemic spinal cord damage. However, delayed treatment with HBO did not change the prognosis.     

Treatment with exogenous surfactant stimulates endogenous surfactant synthesis in premature infants with respiratory distress syndrome

OBJECTIVE: Treatment of preterm infants with respiratory distress syndrome (RDS) with exogenous surfactant has greatly improved clinical outcome. Some infants require multiple doses, and it has not been studied whether these large amounts of exogenous surfactant disturb endogenous surfactant metabolism in humans. We studied endogenous surfactant metabolism in relation to different amounts of exogenous surfactant, administered as rescue therapy for RDS. DESIGN: Prospective clinical study. SETTING: Neonatal intensive care unit in a university hospital. PATIENTS: A total of 27 preterm infants intubated and mechanically ventilated for respiratory insufficiency. INTERVENTIONS: Infants received a 24-hr infusion with the stable isotope [U-13C]glucose starting 5.3 +/- 0.5 hrs after birth. The 13C-incorporation into palmitic acid in surfactant phosphatidylcholine (PC) isolated from serial tracheal aspirates was measured. Infants received either zero (n = 5), one (n = 4), two (n = 15), or three (n = 3) doses of Survanta (100 mg/kg) when clinically indicated. MEASUREMENTS AND MAIN RESULTS: Using multiple regression analysis, the absolute synthesis rate (ASR) of surfactant PC from plasma glucose increased with 1.3 +/- 0.4 mg/kg/day per dose of Survanta (p = .007) (mean +/- SEM). The ASR of surfactant PC from glucose was increased by prenatal corticosteroid treatment with 1.3 +/- 0.4 mg/kg/day per dose corticosteroid (p = .004), and by the presence of a patent ductus arteriosus with 2.1 +/- 0.7 mg/ kg/day (p = .01). CONCLUSION: These data are reassuring and show for the first time in preterm infants that multiple doses of exogenous surfactant for RDS are tolerated well by the developing lung and stimulate endogenous surfactant synthesis.     

肢体缺血后处理促进缺血性脑损伤大鼠内源性神经干细胞的增殖

背景：远程肢体缺血预处理应用到脑缺血-再灌注损伤领域的研究已有一些报道,但肢体缺血后处理应用于该领域报道很少。目的：观察肢体缺血后处理对缺血性脑损伤大鼠侧脑室旁神经干细胞增殖的影响。方法：利用改良线栓法制作局灶性脑缺血大鼠模型,将30只造模成功的SD大鼠随机分为实验组和对照组,每组15只。实验组行远程肢体缺血后处理,对照组不做处理。2组大鼠分别于造模后5,10,15d处死取脑,处死前1d每隔8h腹腔注射50mg／kg5-嗅脱氧尿嘧啶核苷1次,共3次。应用免疫组织化学方法检测梗死灶区大鼠脑组织5嗅脱氧尿嘧啶核苷阳性细胞数。结果与结论：与对照组比较,实验组脑再灌注损伤程度呈现不同程度减轻,行为学评分降低（P〈0．05）。实验组各时间点梗死灶周边皮质的5-嗅脱氧尿嘧啶核苷阳性细胞数明显多于对照组（P〈0．05）。提示局灶性脑缺血造模后的肢体缺血后处理可以改善大鼠行为学表现,促进了内源性干细胞的激活增殖,对缺血性脑损伤有保护作用。     

Dysaggregants effect of platelet aggregation in patients with non-ST segment elevation acute coronary syndrome

AIM: To study efficacy of treating patients with acute coronary syndrome (ACS) without ST segment elevation (STSE) with platelet dysaggregation drugs (aspirin, cardiomagnil, clopidogrel). MATERIAL AND METHODS: 78 ACS without STSE were randomized into five groups: group 1 patients (n = 17) received no dysaggregants; patients of group 2 (n = 26) received aspirin in the dose 250 mg on the day of admission and then 125 mg/day; group 3 was given cardiomagnil (150 mg on the day of admission and then 75 mg/day, n = 17); group 4--clopidogrel 75 mg/day (n = 7); group 5--combination of clopidogrel 75 mg/day with cardiomagnil 75 mg/day (n = 11). All the patients were administered fraxiparin 86 IU/kg sc each 12 hours for 5-8 days. RESULTS: Group 1 patients showed platelet hyperaggregation, platelet aggregation decreased in groups 2, 3 and 4 (6 patients of group 1 were resistant to aspirin). The highest antiaggregation effect was achieved in group 5. CONCLUSION: Control over antiaggregation treatment in patients with ACS without STSE by monitoring of platelet function open broad opportunities for selection of effective individual therapy.     

醒脑启智胶囊药物血清对PC12细胞缺氧损伤的保护作用

背景血管性痴呆的发生与脑缺血缺氧河北省有关,前期的研究表明临床效方-醒脑启智胶囊可明显改善血管性痴呆小鼠的行为学障碍,但其作用途径是否为保护缺氧细胞从而改善血管性痴呆症状.目的采用血清药理学方法,体外培养嗜铬细胞瘤PC12细胞,用Na2S2O4产生缺氧损伤,观察醒脑启智药物血清是否对缺氧损伤的PC12细胞具有保护作用.设计随机对照实验.单位河北医科大学中医学院.对象实验于2003-06/12在河北医科大学动物实验室和细胞培养实验室进行.40只SD大鼠随机分成5组,即对照血清组(n=12)和醒脑启智药物血清25.42,12.71,6.35,3.18 g/kg组(n=7).PC12细胞株购自中国医学科学院细胞中心.方法①药物血清制备醒脑启智药物血清25.42,12.71,6.35,3.18 g/kg组按相应剂量以醒脑启智药物(枸杞子、石菖蒲、川芎、橘络等)灌胃给药,对照血清组以生理盐水10mL/kg灌胃,均为2次/d,每天灌胃间隔12 h,连续给药3 d,末次给药后1h麻醉状态下股动脉采血,分离血清.②PC12细胞分组培养将体外培养的PC12细胞分为6组对照组加入对照血清培养;模型组加对照血清培养1 h后加入Na2S2O4产生缺氧损伤;醒脑启智25.42,12.71,6.35,3.18 g/kg组分别加入5%不相应剂量的药物血清,培养1 h后加入Na2S2O4.③观察指标各组细胞加入Na2S2O4培养16 h后,倒置相差显微镜下观察PC12细胞形态变化;计算乳酸脱氢酶释放抑制率和PC12细胞损伤的抑制率(MTT法)来评估细胞活力.主要结局观察①各组PC12细胞的形态学观察.②各组PC12细胞的乳酸脱氢酶活性释放抑制率和PC12细胞损伤的抑制率.结果①细胞形态醒脑启智各剂量组PC12细胞折光性较好,细胞碎片形成减少.②乳酸脱氢酶活性释放抑制率醒脑启智25.42,12.71,6.35,3.18g/kg组分别为81.6%,69.6%,54.4%,27.8%.③PC12细胞损伤的抑制率醒脑启智25.42,12.71,6.35,3.18 g/kg组分别为82.9%,75.6%,65.9%,53.7%.结论醒脑启智药物血清能明显减轻PC12细胞的缺氧损伤,可增强细胞活力,降低乳酸脱氢酶活性,并呈现一定的剂量依赖关系.     

实验性动脉粥样硬化家兔主动脉鞘磷脂酶活性与神经酰胺含量变化和大黄素的干预作用

背景神经酰胺信号转导途径可能在致血管内皮细胞凋亡、进而引起泡沫细胞的形成,与平滑肌细胞增殖等动脉粥样硬化发生、发展过程中起重要作用.目的观察家兔实验性动脉粥样硬化发生时主动脉鞘磷脂酶活性、神经酰胺含量的变化以及大黄素的干预作用,并与阳性药物非诺贝特进行对照.设计完全随机对照设计.单位中山大学药学院药理毒理实验室.材料实验于2003-07/12在中山大学药学院药理毒理实验室完成,选择新西兰雄性家兔48只,用高胆固醇饮食复制动脉粥样硬化模型40只,另设8只为正常对照组,模型动物随机分为模型组、大黄素5 mg/kg组、大黄素10 mg/kg组、大黄素20 mg/kg组、非诺贝特25 mg/kg组,每组8只.方法各组在模型复制的第7周起开始用药.大黄素各组每日分别灌胃5 mg/kg,10 mg/kg,20 mg/kg大黄素;非诺贝特25 mg/kg组每日灌胃25 mg/kg非诺贝特,各药用2 mL生理盐水制成混悬剂,1次/d,正常对照组及模型组灌胃等剂量生理盐水,共4周.每只家兔给予喂养食物限制在135～150g/d,动物分笼饲养.主要观察指标[1]各组家兔主动脉内膜脂质斑块面积.[2]各组家兔血清总胆固醇、三酰甘油含量.[3]各组家兔血浆超氧化物歧化酶活性与丙二醛含量.[4]各组家兔主动脉壁鞘磷脂酶活性和神经酰胺含量.结果48只家免均进入实验分析.[1]主动脉内膜脂质斑块面积百分率模型组血管内膜脂质斑块面积(48.87±15.5)%,大黄素各组均小于模型组(P＜0.05或0.01),以大黄素10 mg/kg组作用明显(22.19±12.9)%.非诺贝特25 mg/kg组与模型组基本一致(P＞0.05).[2]血清总胆固醇及三酰甘油含量正常对照组家兔主动脉内膜光滑;大黄素各组血清总胆固醇及三酰甘油含量与模型组基本一致(P＞0.05).非诺贝特25 mg/kg组显著低于模型组(P＜0.05).[3]血浆超氧化物歧化酶活性与丙二醛含量大黄素各组家兔血超氧化物歧化酶活性显著高于模型组(P＜0.05,P＜0.01),丙二醛含量大黄素10 mg/kg,20 mg/kg组均显著低于模型组(P＜0.05).非诺贝特25 mg/kg组与模型组基本一致(P＞0.05).[4]主动脉鞘磷脂酶活性与神经酰胺含量模型组明显高于正常对照组,大黄素5,10,20 mg/kg组明显低于模型组.非诺贝特25 mg/kg组与模型组基本一致(P＞0.05).[5]相关性分析主动脉鞘磷脂酶活性与血胆固醇含量呈正相关(r=0.542,P＜0.01)、与血丙二醛水平呈正相关(r=0.789,P＜0.01),与血超氧化物歧化酶活性呈负相关(r=-0.936,P＜0.01);神经酰胺含量与血胆固醇含量呈正相关(r=0.433,P＜0.05),与血丙二醛水平呈正相关(r=0.673,P＜0.01),与血超氧化物歧化酶活性呈负相关(r=-0.876,P＜0.01).结论大黄素降低总胆固醇、三酰甘油含量的作用不明显,但通过抗氧化、抑制神经酰胺通路的激活、降低鞘磷脂酶活性与神经酰胺的含量,保护了血管内皮细胞,动脉内膜脂质斑块面积明显减少,提示大黄素抗实验性动脉粥样硬化作用与调节神经胺信号转导途径密切相关.     

Determination of the role of conventional, novel and atypical PKC isoforms in the expression of morphine tolerance in mice

This study comprehensively determines the role of all the major PKC isoforms in the expression morphine tolerance. Pseudosubstrate and receptors for activated C-kinase (RACK) peptides inhibit only a single PKC isoform, while previously tested chemical PKC inhibitors simultaneously inhibit multiple isoforms making it impossible to determine which PKC isoform mediates morphine tolerance. Tolerance can result in a diminished effect during continued exposure to the same amount of substance. In rodents, morphine pellets provide sustained exposures to morphine leading to the development of tolerance by 72 h. We hypothesized that administration of the PKC isoform inhibitors i.c.v. would reverse tolerance and reinstate antinociception in the tail immersion and hot plate tests from the morphine released solely from the pellet. Inhibitors to PKC alpha, gamma and epsilon (100-625 pmol) dose-dependently reinstated antinociception in both tests. The PKC beta(I), beta(II), delta, theta, epsilon, eta and xi inhibitors were inactive (up to 2500 pmol). In other mice, the degree of morphine tolerance was determined by calculating ED50 and potency-ratio values following s.c. morphine administration. Morphine s.c. was 5.6-fold less potent in morphine-pelleted vs. placebo-pelleted mice. Co-administration of s.c. morphine with the inhibitors i.c.v. to either PKC alpha (625 pmol), gamma (100 pmol) or epsilon (400 pmol) completely reversed the tolerance so that s.c. morphine was equally potent in both placebo- and morphine-pelleted mice. The PKC beta(I), beta(II), delta, theta, epsilon, eta and xi inhibitors were inactive. Thus, PKC alpha, gamma and epsilon appear to contribute to the expression of morphine tolerance in mice.     

远程预处理对兔脊髓缺血再灌注损伤的保护作用(英文)

目的:探讨远程预处理对兔脊髓缺血再灌注损伤的保护作用。方法:20只成年雄性新西兰大白兔随机分成2组(各组n=10),即对照组和远程预处理(RPC)组。所有动物脊髓缺血前1h戊巴比妥钠麻醉动物(30mg/kg,iv)。RPC组动物麻醉后进行双后肢短暂缺血2次(充气式压力止血带环扎双后肢,压力26.6kPa,阻断10min,松开10min,再阻断10min),最后一次缺血后再灌注30min,阻闭肾下腹主动脉20min,制作兔脊髓缺血模型。对照组动物不进行双后肢短暂缺血,其余同RPC组。再灌注后4,8,12,24和48h分别对动物后肢运动功能评分。再灌注48h后,处死动物取脊髓(L5～7),石蜡包埋切片行组织病理学观察。结果:RPC组神经功能评分在各时间点均明显高于对照组(P=0.000);与对照组相比,RPC组脊髓前角正常神经细胞数明显增多(P=0.000),且神经功能评分与脊髓前角正常神经细胞计数之间有显著相关性(r=0.868,P<0.01)。结论:远程预处理对兔脊髓缺血再灌注损伤有显著的保护作用。     

Antifungal effects of the nonlinear pharmacokinetics of cilofungin, a 1,3-beta-glucan synthetase inhibitor, during continuous and intermittent intravenous infusions in treatment of experimental disseminated candidiasis.

Cilofungin (LY-121019) is a fungicidal cell wall-active 1,3-beta-glucan synthetase inhibitor with a short plasma half-life and saturable nonlinear plasma pharmacokinetics. To optimize the in vivo efficacy of this compound, we studied the effects of its linear and nonlinear pharmacokinetics during continuous versus intermittent intravenous infusion of cilofungin in the treatment of experimental disseminated candidiasis in persistently granulocytopenic rabbits. Six groups of rabbits were studied, untreated controls (n = 32) and five cilofungin dosage regimen groups consisting of the following: 25 mg/kg of body weight intravenously twice daily (VLoINT) (n = 9); 50 mg/kg twice daily (LoINT) (n = 9); 90 mg/kg twice daily (HiINT) (n = 11); 5 mg/kg/h for 18 h/day (LoCI) (n = 7); and 10 mg/kg/h for 18 h/day (HiCI) (n = 7). All regimens achieved plasma concentrations exceeding the MIC for Candida albicans (0.25 microgram/ml). In vitro timed kill assays found that the fungicidal activity and rate of kill by cilofungin above the MIC for C. albicans was concentration dependent. At the lower dosage regimens (VLoINT, LoINT, and LoCI), cilofungin followed linear plasma pharmacokinetics, whereas at higher doses (HiCI and HiINT), nonlinear kinetics consistent with a saturated elimination pathway(s) were observed. Only HiCI and HiINT produced a 10(3)- to 10(4)-fold reduction in CFU per gram in candidiasis of the brain (P less than or equal to 0.001). HiCI and HiINT also significantly reduced infection in the choroid (P less than or equal to 0.05). All regimens, except VLoInt, significantly (P less than or equal to 0.01) reduced tissue infections in lung, liver, spleen, and kidney. However, only the regimens with nonlinear saturation kinetics (HiCI and HiINT) produced a 10(6) reduction in the spleen and a > 10(5) reduction of C. albicans in the kidney and liver. A simple doubling of the dosage from LoCI to HiCI resulted in tissue concentrations that were 10 times higher and a 10(2)- to 10(4)-fold-greater antifungal effect. There was a direct correlation (r2 = 0.83) between tissue concentrations of cilofungin and antifungal activity. Thus, continuous and intermittent infusion dosage regimens that elicit nonlinear saturation plasma pharmacokinetics of cilofungin were associated with increased antifungal activity against experimental disseminated candidiasis.