深低温保存增强血小板促凝血功能的研究

为了探索血小板冰冻保存后膜表面促凝血活性相关分子变化与冰冻血小板体内即刻止凝血功能增强之间的可能联系，用流式细胞术检测了新鲜血小板冰冻保存前后V因子结合能力、血小板膜表面GPIb—Ⅸ-V分子（CD42a）密度，用血凝仪测定激活血小板诱导血浆凝固时间（aPACT）变化，用血细胞计数仪测定血小板计数、NIPV和PDW。研究结果表明，与新鲜血小板比较，深低温保存后血小板激活血小板诱导血浆凝固时间缩短43．9％；结合V因子的荧光强度平均增加117％；结合膜表面GPIb—Ⅸ—V分子的荧光强度增加32％。结论：冰冻血小板体内即可止凝血功能增强，可能与血小板冰冻保存后膜表面促凝血活性分子表达增加或功能增强，促凝血功能明显增强，发挥快速止血功能有关。     

不同渗透压NaCl溶液对红细胞的影响

目的 检测不同渗透压NaCl溶液中红细胞的溶血率、MCV和RDW的变化,探讨渗透压对红细胞影响.方法 用渗透压仪检测不同浓度NaCl溶液的渗透压;用手工法计数红细胞在不同渗透压NaCl溶液中未溶血红细胞数,计算不同渗透压NaCl溶液中红细胞溶血率;用细胞计数仪检测未溶血红细胞的MCV和RDW值.结果 0.10％～1.00％NaCl溶液浓度（g/ml）与渗透压（mOsm/kg）之间的直线回归方程为：Y=4.035 7＋31 829.864 3X;NaCl溶液渗透压在195 mOsm/kg至131 mOsm/kg区间,溶液中红细胞溶血较明显;NaCl溶液渗透压在195 mOsm/kg以下时,未溶血红细胞MCV值减小较明显、未溶血红细胞RDW值增大较明显.结论 0.1％～1.00％ NaCl溶液浓度与渗透压之间存在直线回归关系;且NaCl溶液渗透压降低,红细胞溶血率增高、未溶血红细胞的MCV值减小、未溶血红细胞的RDW值增大.     

不同常规保存血小板冰冻保存效果研究

目的了解常规保存不同时间的机采血小板冰冻前后质量指标变化及输注疗效，探讨血小板冰冻处理前常规保存调控的最佳方案。方法对120袋机采血小板随机分成6组，在（22±2）℃平床振荡条件下，分别保存0、1、2、3、4、5d然后制备冰冻血小板，并对血小板冰冻前与复温后分别计数血小板，检测pH值，跟踪调查输注冰冻血小板的患者，计算回收率。结果有效期内（22±2）℃振荡保存的血小板产品中血小板计数无显著性差异，pH值下降明显；冰冻前后血小板计数有显著性差异，pH值无差异。保存3d内的血小板冰冻后血小板的输注回收率无差异，与保存4d、5d的血小板冰冻后的回收率有显著差异。结论（22±2）℃振荡保存3d内的血小板可以制备冰冻血小板，保存4-5d的血小板可以输注但不宜制备冰冻血小板。     

采集后6小时与72小时制备的冰冻单采血小板质量研究

目的通过比较采集后6h和72h制备的冰冻单采血小板制品的多项质量参数，为冰冻单采血小板的制备标准提供依据。方法以美国产Trima血细胞分离机配套全密闭7d保存袋采集的单采血小板，分别于采集后6h和72h制备为冰冻血小板制品，1周后复苏留样，分别检测血小板计数（PLT，MPV，PCT，PDW）、血小板粘附性、血小板P选择蛋白、PF3A、PF4、pH值、血块收缩试验（血浆法）。结果采集后6h和72h制备的冰冻单采血小板，两者相比差异无统计学意义（t〈0．01，P〉0．05）。单采血小板在不同保存条件下，PF3A均保持了良好的PF3活性，单采血小板在常规或冰冻保存条件下，PF4及P选择蛋白的表达均明显增加，采集后6h和72h制备的冰冻单采血小板相比，差异无统计学意义（t〈0．01，P〉0．05）；单采血小板在常规保存3d内，粘附功能和血块收缩试验没有明显变化，而冰冻保存的单采血小板这两项指标呈明显减退现象，血小板的活力下降明显。结论以美国产Trima血细胞分离机配套全密闭7d保存袋采集的单采血小板，分别于采集后6h和72h制备的冰冻血小板制品，两者的体外指标分析结果相比差异无显著性，且都能有效的改善和控制急性大出血患者的出血倾向，用于抢救急性大出血患者疗效是可靠的。     

红景天苷用于单采血小板保存的研究

目的 研究添加不同浓度红景天苷（salidroside,Sal）对血小板体外保存期间形态、代谢及活化等影响。方法将血液成分分离机采集的每份单采血小板均分为5袋,空白对照组（A组）不做任何添加,另外4袋中分别加入不同浓度的Sal溶液,终浓度为5μmol/L(B组)、25μmol/L(C组)、40μmol/L(D组)和50μmol/L(E组),（22±2）℃振荡保存,分别在保存的第1、3、5、7、10、14天抽样,进行血小板参数检测、血气生化检测、血栓弹力图试验、流式细胞术检测和sCD40L浓度检测。结果 各组单采血小板的血小板计数随保存时间延长无明显变化（P>0.05）,平均血小板体积（MPV）在保存前10d内无显著变化,14d时均显著增大（P <0.05）,血小板体积分布宽度（PDW）随保存时间延长均有不同程度的变化（P <0.05）;在相同保存时间,各组之间单采血小板计数、MPV、PDW值比较无明显差异。各组单采血小板保存7d内的pH值明显降低（P <0.05）,LAC值不断升高（P <0.05）,保存14d的GLU值明显降低（P <0.05）。保...     

低温保存的血小板胞内冰晶形成温度测定

血小板胞内冰晶形成（ⅡF）的温度是指导血小板低温保存最重要的物理参数之一。本研究通过生物学和物理学的两种方法同时测定血小板ⅡF温度范围，在分步降温法中，每降5℃取出血小板样本，测定37℃直接复温（T37℃）和经液氮处理后再37℃复温（LN）两种方法处理的血小板样本磷脂酰丝氨酸（PS），血浆乳酸脱氢酶（LDH）和血小板聚集功能的变化，同时利用差式扫描量热计（DSC）记录加和不加5%DMSO的血小板在降温过程中的放热峰。结果表明，PS，LDH和血小板聚集功能在-35℃左右不再发生变化，DSC测定结果表明，代表血小板ⅡF的第二个小放热峰在-35℃左右。结论：血小板ⅡF温度在-30℃至-40℃之间（-35℃左右）。     

酸性氧化电位水消毒剂的研究进展北大核心

酸性电解水（Acidic Electrolyzed Water,AEW）,又称酸性氧化电位水,是指将低浓度的氯化钠溶液（浓度低于0.1%）加入水中,通过电化学方法进行电解而制成的一种消毒剂。由于溶液的p H值和氧化还原电位（ORP）发生改变,并含一定浓度的有效氯和活性氧,从而拥有杀灭微生物功能〔1〕。该项技术1982年在日本研究成功,     

化学诱导剂对血小板钙离子浓度变化的影响

目的探讨化学诱导剂作用下不同人群血小板钙离子浓度的变化。方法（1）以不同浓度的ADP、凝血酶、胶原、花生四烯酸、5-HT激活血小板，用流式细胞仪观察20例正常健康人血小板钙离子浓度变化。（2）用ADP、胶原、花生四烯酸、5-HT激活血小板，用流式细胞仪观察心肌梗死患者及高血压患者（各20例）血小板钙离子浓度的变化。（3）用花生四烯酸激活血小板，用流式细胞仪观察20例心肌梗死患者口服阿司匹林前后血小板钙离子浓度的变化。结果（1）ADP、瑞斯托酶素、胶原、花生四烯酸、5-HT血小板激活剂均可导致血小板钙离子浓度升高（P〈0．05），而且在一定范围内，钙离子浓度的升高幅度随激活剂的浓度升高而增加。没有观察到凝血酶导致血小板钙离子浓度升高。（2）同样激活剂刺激下，心肌梗死患者和高血压患者血小板钙离子浓度升高的幅度均高于正常健康人（P〈0．05）。（3）服用阿司匹林后心肌梗死患者血小板钙离子浓度下降的幅度低于正常健康人（P〈0．05）。结论化学诱导剂对血小板的激活过程与钙离子浓度的变化密切相关；心肌梗死、高血压患者可能存在血小板钙通道活性增高；钙离子能反应服用阿司匹林后血小板的功能状态，检测血小板钙离子对阿司匹林的疗效监测有一定的价值．     

含6%二甲基亚砜的血小板的冷冻及-80℃或-135℃保存无需解冻后处理

在0.9％氯化钠(NaCl)中以27％二甲基亚砜(DMSO)处理人类单个献血员和狒狒血浆中的血小板,终浓度为6％,并浓缩以除去含95％DMSO的上清。将血小板重悬浮于300ml聚氯乙烯(PVC)袋中余下的10ml溶液或500ml乙烯乙基乙酸(EVA)袋中余下的15ml溶液中,外包有聚酯袋,置于一纸盒,并以2～3℃/min的速度在机械式冻箱中冷至～80℃。PVC袋冻存于-80℃而EVA袋冻存于-135℃冷冻箱中。每单位血小板约含600mgDMSO,将其解冻,并以10ml 0.9％NaCl稀释,然后输注。F—T回收率为85％,流动血细胞计数仪测得70％的为完整血小板而30％的为血小板微聚集。两只狒狒和一名正常志愿献血者     

一氧化碳-血红蛋白携氧载体对小鼠脓毒性脑病的作用及其机制

目的 探讨一氧化碳-血红蛋白携氧载体（carbon monoxide-hemoglobin based oxygen carrier,CO-HBOC）对脓毒性脑病（sepsis-associated encephalopathy,SAE）的作用及其机制。方法 选取SPF级雄性C57BL/6小鼠136只,采用随机数字表随机分为4组：Sham组（假手术处理,术后1h尾静脉注射0.9%氯化钠溶液）、CLP组（建立脓毒症模型,术后1h尾静脉注射0.9%氯化钠溶液）、O2-HBOC组（建立脓毒症模型,术后1h尾静脉注射0.3 Hb/kg O2-HBOC）和CO-HBOC组（建立脓毒症模型,术后1h尾静脉注射0.3 Hb/kg CO-HBOC）。采用盲肠结扎穿刺法建立脓毒症小鼠模型,Morris水迷宫实验观察认知功能。术后24h取脑组织切片采用原位末端标记法（TdT-mediated dUTP nick end labeling,TUNEL）/神经元核（neuronal nuclei,NeuN）/4,6-二氨基-2-苯基吲哚（4,6-diamino-2-phenyl indole,DAPI）荧光染...     

Isolation, identification, and analysis of 4-acetylaminophenol-glucuronide in body fluids of dialyzed renal patients; a molecular mass marker for peritoneal diffusive transport

A noncharacteristic solute, appearing in gradient elution liquid chromatography (HPLC) profiles of body fluids of dialyzed renal patients, was isolated and identified by preparative HPLC, beta-glucuronidase induced enzymatic peak shift, and mass spectrometry. The compound was shown to be p-acetylaminophenol ('paracetamol')-glucuronide (PG). Serum and peritoneal dialysate PG concentrations were determined in a number of patients. Cuprophan in vivo dialyzer clearances were calculated. Peritoneal membrane mass transfer coefficients (MTC) of PG were calculated and compared with those of molecular mass markers for peritoneal diffusive mass transport studies (urea, creatinine, uric acid, and inulin). By extrapolation of an MTC versus molecular mass calibration line for urea, creatinine, and uric acid it is shown that PG behaves as expected from its molecular mass. We suggest that PG (Mr = 327) is suitable as a molecular mass marker for the molecular mass range between Mr 200 and 500. It may also be used as a marker for diffusive solute transport in hemodialysis treatment. The HPLC gradient elution technique used here appears to be suitable for the simultaneous analysis of the molecular mass markers creatinine, uric acid, and paracetamolglucuronide.     

In vivo evidence of impaired solute transport by the thick ascending limb in potassium-depleted rats.

The objective of this investigation was to determine if thick ascending limb (TAL) solute removal is impaired in potassium-depleted rats, in vivo. We estimated TAL NaCl concentration by measuring in situ conductivity of tubular fluid presented to the early distal site after stop-flow periods of 10-60 s, during which a proximal equilibrium solution remained in contact with the reabsorbing epithelium. This allowed us to calculate the rate constant of the decrease in tubular fluid NaCl concentration and to determine equilibrium values for control, potassium-depleted, and potassium-repleted rats. After 60 s of stop-flow, NaCl concentration of TAL fluid decreased to 18.3 +/- 2.73 mM in control rats, while potassium-depleted rats had values almost twice as high (36.5 +/- 2.97 mM, P less than 0.01). The amount of NaCl remaining after 60 s of stop-flow in K-depleted rats was highly correlated with the plasma K concentration. Calculated rates of NaCl efflux from the TAL appeared to be normal in K-depleted rats while the concentration of NaCl achieved at equilibrium was nearly twice that measured in control rats. Acute systemic administration of KCl by gavage or infusion in K-depleted rats was associated with a decrease in TAL NaCl concentration to normal values. Addition of K to the perfusate, however, did not repair the defect. Our results can best be explained by assigning a special role to the peritubular K concentration. We suggest that the defect in TAL solute removal in K-depletion can be rapidly reversed, because decreases in peritubular K concentration limit Na efflux across the peritubular membrane by decreasing the activity of the Na-K-ATPase pump. We recognize that factors such as regional renal blood flow, local angiotensin II levels, and products of the cyclo-oxygenase enzyme system may play a role.     

Mass Transfer Kinetics for Osmotic Dehydration of Kinnow Fruit in Sugar Solution

Mass transfer kinetic study was carried out for sheet geometry of whole kinnow fruit in sugar solution. The experiments were conducted using completely randomized design with the sucrose concentration (55–75°B) at various process temperatures (35–65 °C) and solution to fruit ratio (3–7:1 v/w) at varying immersion time interval (30–270 min). The water loss, solute gain and mass loss was systematically examined and recorded throughout the process. The water loss and solute gain for osmotic dehydration of kinnow was found to be at osmotic process temperature of 65 °C, sugar solution concentration of 65–75°B, solution to fruit ratio of 5:1 and immersion time of 270 min. The effective moisture and solute diffusivities was calculated. The maximum diffusivity of water was found to be 53.08 × 10⁻⁹ m²/s and minimum diffusivity of solute observed was 0.49 × 10⁻⁹ m²/s.

     

Preparation of theophylline hydrogels of atactic poly(vinyl alcohol)/NaCl/H2O system for drug delivery system.

Theophylline (TH) was loaded in an a-PVA/NaCl/H2O hydrogels system by one cycle gelation only at -20 degrees C. However, it developed some unwanted crystal-like structure surrounding the hydrogels while kept at room temperature. The physical, chemical and thermal analyses of this crystal-like structure indicated TH embedded with thin hydrogels of a-PVA/NaCl. Later during dissolving of feed-mixture at least 3 h heat treatment with proper mixing at high temperature contributed hydrogels of almost no crystal-like structure. 3% of TH was successfully loaded by this way. This type of hydrogels showed Fickian type drug release (Higuchi Model) and it showed a more sustained effect than that of traditional cyclic FT. Comparatively lower release rate, diffusion coefficient and kinetic constant values of this system prevail over other systems studied here. A DSC thermogram revealed that apparently homogeneous microgel junctions might play the key role behind the above properties. Moreover the a-PVA/TH/NaCl/H2O system depresses the freezing point at -30 degrees C instead of above this temperature. The hydrogels of this system were also prepared by freezing at -30 degrees C for 16 h as one cycle. Three cycles were done in cyclic FT (freezing at -30 degrees C for 16 h and thawing at room temperature for 8 h). Drug release was studied for a total of 750 min. Up to the asymptotic value, 10.5 h TH release from the hydrogel matrices of the a-PVA/NaCl/H2O system (gelation at -20 degrees C) and 6.5 h from those of a-PVA/NaCl/H2O (freezing at -30 degrees C) and a-PVA/H2O systems (cyclic FT) were found.     

Evaluation of platelet cryopreservation techniques by isolated kidney perfusion

The isolated perfused rabbit kidney, a model system used previously to assess platelet function, was adapted for evaluation of human platelet cryopreservation techniques. A new, simple, efficient device for controlling cooling rates before, during, and after freezing was used. Platelet concentrates frozen with 5 per cent dimethyl sulfoxide (DMSO) under different conditions were the most effective of those tried in maintaining the hemostatic function and vascular integrity of perfused kidneys. Our studies indicate that the isolated, perfused rabbit kidney can be used to evaluate platelet cryopreservation techniques and is potentially adaptable for studies of organ cryopreservation.     

2种方法制备的血小板凝胶释放PGFs含量及生物活性的初步研究

目的了解血小板凝胶(PG)释放血小板生长因子(PGFs)的动力学过程及其对细胞增殖作用的影响,比较凝血酶-Ca和CaCl22种PG制备方法。方法将8份浓缩血小板每份分为2份组成2组,分别加入凝血酶-Ca和CaCl2处理,并在处理前(0点)以及处理后的1、2、4和6 h分别取样,用ELISA方法检测其中PGFs的含量;将L929细胞在含有1%、5%、10%、20%和30%、40%的PG上清的培养基中培养,无血清培养基为阴性对照,10%FBS为阳性对照,分别在培养的24、48和72 h应用CCK-8试剂盒测定细胞数量,考察2种方法处理6 h的样品对细胞增殖的影响。结果 CaCl2和凝血酶-Ca法制备的PG在6 h释放的PDGF-AB含量分别为(101.37±26.09)vs(127.64±33.81)ng/ml,TGF-β1含量分别为(101.08±20.36)vs(107.09±13.72)ng/ml;PG上清对细胞增殖具有明显的促进作用,细胞培养72 h相对于阴性对照的细胞增殖倍数,CaCl2组由1%～40%浓度分别为(1.53±0.24)、(1.88±0.21)、(1.92±0.50)、(1.73±0.61)、(1.71±0.50)、(1.39±0.67)倍,凝血酶-Ca组分别为(1.68±0.29)、(1.90±0.19)、(1.88±0.70)、(1.53±0.65)、(1.51±0.59)、(1.09±0.55)倍,2组不同浓度的上清细胞增殖促细胞增殖作用均高于阴性对照组(P0.05),同一时间点,2组PG上清浓度从1%增至10%,促作用随之增加,当浓度达到20%时,促细胞增殖作用开始下降。结论凝血酶-Ca法和CaCl2法制备的PG均在1 h内基本完全释放PDGF-AB、TGF-β1 2种主要PGFs;2种方法制备的PG上清均在一定的浓度范围内对细胞增殖具有促进作用。     

Sodium chloride, urea, and water transport in the thin ascending limb of Henle. Generation of osmotic gradients by passive diffusion of solutes

Studies were designed to examine whether the thin ascending limb of Henle (tALH) decreases its luminal solute concentration by an active or a passive transport process. In all experiments isolated segments of rabbit tALH were perfused in vitro. When tubules were perfused with solutions identical to the bath, active transport of NaCl was excluded by the following: (a) osmolality of the collected fluid remained unchanged and the same as the bath. (b) net water reabsorption could not be demonstrated, and (c) transtubular potential difference was zero. Isotopic permeability coefficients (x 10(-5) cm s-1) were calculated from the disappearance rate of the respective isotope added to the perfusate. These values indicate that tALH is moderately permeable to [14C]urea (6.97 +/- 1.95) while having a higher permeability to 22Na (25.5 +/- 1.8) and [not readable: see text]Cl (117 +/- 9.1) than any other segment similarly studied. The influx (bath-to-lumen) isotopic permeabilities were not statistically different from the above efflux permeabilities. Osmotic water permeability was immeasurably small. When tALH were perfused with a 600 mosmol/liter solution predominantly of NaCl against a 600 mosmol/liter bath in which 50% of osmolality was NaCl and 50% urea (to simulate in vivo papillary interstitium), the collected fluid osmolality was decreased significantly below that of the bath (300 mosmol/liter/mm of tubule). The decrease in osmolality was due to greater efflux of NaCl as compared to influx of urea. We conclude that active transport of salt by the tALH was not detected by the experimental protocol of the current studies, and that the unique membrane characteristics of tALH allows for generation of osmotic gradients (lumen less concentrated than adjacent surroundings) on purely passive mechanisms when perfused with isosmolal salt solutions in a bath with appropriate salt and urea concentrations. These findings are consistent with the passive counter-current model previously proposed from this laboratory.     

深低温保存血小板匀速和非匀速降温模式比较研究

目的评估3种降温模式对冷冻保存血小板质量的影响,优化深低温保存血小板降温技术。方法随机选取8人份血小板,每人份等分3份并随机配对分为A、B、C组,分别采用传统匀速(-1℃/min)降温模式、-80℃低温冰箱降温模式和非匀速降温模式进行冷冻降温处理。各组降温至终点后取出,均采用37℃循环式水浴箱复温,然后检测血小板计数(Plt)、血小板平均体积(MPV)、血小板分布宽度(PDW)、血浆乳酸脱氢酶(LDH)、乳酸(LA)、pH、CD62p阳性率、磷脂酰丝氨酸(PS)阳性率、CD62p再表达率、玻片法血小板聚集实验(SPAT)、激活血小板血浆凝固时间(APCT)。结果1)3组Plt、PDW、pH、LA、aPCT均差异无显著性统计学意义(P>0.05)。2)B组和C组各项指标差异无显著性统计学意义(P>0.05)。3)B组和C组MPV、CD62p再表达率、SPAT明显优于A组,差异有显著性统计学意义(P<0.01)。A组、B组和C组MPV分别为(5.81±0.90)fl,(5.61±0.91)fl,(5.68±0.81)fl;A组、B组和C组CD62p再表达率分别为(52.4±7.8)%,(55.0±8.6)%,(57.0±8.3)%;A组、B组和C组SPAT分别为(123±14)s,(111±13)s,(110±16)s。4)B、C组血浆LDH水平明显低于A组,差异有显著性统计学意义(P<0.05)。A组、B组和C组血浆LDH分别为(127±22)U/L,(120±20)U/L,(122±22)U/L。结论1)匀速降温不是血小板最理想的冷冻降温方式;2)能保证-10℃—-40℃温度段降温平均速率在(-1—-3)℃/min间的非匀速降温模式不仅具有可操作性强的明显优势,而且更加符合血小板低温生物学特性,有利于提高血小板保存质量。     

血小板凝胶制备方法的体外实验研究

目的优化血小板凝胶(platelet gel,PG)的制备方法。方法采用CCK-8试剂盒检测不同浓度外源性凝血酶、不同浓度血小板、血小板与激活剂不同比例制备的PG对ECV304细胞增殖的影响;通过细胞迁移试验检测不同浓度外源性凝血酶对ECV304细胞迁移的影响;采用ELISA试剂盒检测不同浓度外源性凝血酶和不同浓度血小板对VEGF释放量的影响。结果 PG促进ECV304细胞增殖和迁移;加入外源性凝血酶PG形成时间为40~60s,而不加外源性凝血酶PG形成时间600~1 200 s,但是不同浓度(0、100、1 000 U/ml)的凝血酶对ECV304细胞增殖和迁移影响甚微;PG促ECV304细胞增殖作用随血小板浓度的增加而增强,血小板浓度处于(1 500~2 500)×109/L时趋于稳定;富血小板血浆(PRP)与激活剂的比例为10∶1时促细胞增殖效果略优于5∶1;PG上清中VEGF含量随着PRP中血小板含量的增加而增加,不同浓度(0、100、1 000U/ml)凝血酶制备的PG上清中VEGF含量的差异,无统计学意义(P>0.05)。结论常规采集PRP的血小板浓度(1 000×109/L左右)已能保证细胞增殖效果、满足用于临床的PG需求;PG是否添加激活剂凝血酶应根据临床实际情况选择。     

In vitro evidence of an endothelial cell-dependent antiplatelet activity for isosorbide dinitrate, but not for its 2- and 5-mononitrate metabolites

In an experimental model in which cultured endothelial cells (EC) and platelets were incubated with autologous plasma, we investigated the pharmacological modulations by isosorbide nitrates (ISN) [isosorbide dinitrate (ISDN) + 2-isosorbide mononitrate (2-ISMN) + 5-ISMN] of the EC-induced inhibition of platelet aggregation; and the associated changes in prostanoid profile of these mixed EC-platelet suspensions. ISDN antiplatelet activities were found to be magnified profoundly by EC, being dependent upon both ISDN concentration and EC number, e.g., 5.10(-5) M ISDN in the presence of 2.10(4) cells, fully arrested ADP-induced aggregation, whereas the same ISDN concentration induced 30% inhibition in control platelet activities. In contrast, there were no significant changes in 2- and 5-ISMN antiaggregating properties, whether incubated in the presence or absence of EC. Thromboxane B2 accumulated noticeably after aggregation, whereas 6-keto-prostaglandin (PG) F1 alpha and PGE2 accumulated poorly in the medium. In the presence of EC, thromboxane B2 accumulation fell in parallel to the extent of aggregation, whereas 6-keto-PGF2 alpha and PGE2 accumulated in the medium. Aspirin-treated, washed ECs still inhibited platelet aggregation. ISDN was the only ISN capable of inducing PG-accumulation profile changes. These results demonstrate the existence of an endothelium-dependent ISDN antiplatelet activity. Furthermore, this effect is specific to ISDN not being shown by its mononitrate metabolites. These results suggest that PG accumulation changes may be a consequence rather than a cause of the inhibition of platelet activity by (ISDN-stimulated) EC.