Role of platelet-activating factor in leukocyte-independent plasma extravasation and mast cell activation during endotoxemia

BACKGROUND: Independently from leukocyte adherence, endothelial factors and mast cell activation seems to promote microvascular permeability. Platelet-activating factor (PAF) has been shown to play a significant role in endotoxin-induced leukocyte adherence. The aim of our study was to investigate if there is also a role for PAF in mediating leukocyte-independent microvascular permeability changes and activation of mast cells during endotoxemia. Therefore, during endotoxemia microvascular permeability and mast cell activation were determined after inhibition of L-selectin-mediated leukocyte adherence by fucoidin and after inhibition of PAF effects by the PAF receptor antagonist BN52021. MATERIALS AND METHODS: In male Wistar rats, red cell velocity (V(RBC)), venular wall shear rate, microvascular permeability, leukocyte adherence, and mast cell activation were determined in mesenteric postcapillary venules using intravital microscopy at baseline and 60 and 120 min after start of a continuous infusion of endotoxin (ETX; 2 mg/kg/h, Escherichia coli O26:B6) (ETX group). Animals in the FUCO/ETX group received fucoidin (25 mg/kg body wt) in addition to the procedure described above. Animals in the FUCO/ETX/PAF-ANT group received fucoidin and the PAF receptor antagonist BN52021 (5 mg/kg body wt) prior to the continuous endotoxin infusion. Control animals (control group) received only equivalent volumes of NaCl 0.9%. RESULTS: There were no microhemodynamic and macrohemodynamic differences between groups. In all endotoxin-challenged groups macromolecular leakage and mast cell activity increased significantly, starting at 60 min. Both macromolecular leakage and mast cell activity were significantly higher in the FUCO/ETX group than in the FUCO/ETX/PAF-ANT group and control group. Differences in macromolecular leakage between groups were significant at 120 min. Differences in mast cell activity between groups were significant at 60 and 120 min. CONCLUSIONS: The results of our study demonstrate a leukocyte-independent plasma extravasation that can be inhibited by the PAF receptor antagonist BN52021, indicating the involvement of PAF in the pathophysiology of leukocyte-independent microvascular damage during early endotoxemia. Mast cell activity seems to precede leukocyte-independent macromolecular leakage.     

Long-term lung preservation with the PAF antagonist BN 52021

Platelet activating factor (PAF, 1-alkyl-2(R)-acetyl-glycero-3- phosphorylcholine) is a phospholipid that is released by a variety of cells. The similarity between the pathophysiological effects of PAF and posttransplant pulmonary dysfunction led to an evaluation of a PAF antagonist as an adjunct to lung preservation. The ginkgolide B, BN 52021, was selected as the PAF antagonist to be studied because of the large data base available on this compound. BN 52021 was given to the donor and recipient (10 mg/kg i.v.) prior to harvest and transplantation and was included in 1 L of preservation solution (10 mg/kg) used for flushing the pulmonary artery and for storage. Left single-lung transplantation was performed following a 22-hr preservation period at 10 degrees C. Arterial oxygen tension (pO2), pulmonary vascular resistance (PVR), alveolar arterial oxygen difference (A-aDO2), and dynamic lung compliance (DLC) were recorded for 6 hours following ligation of the native pulmonary artery. At the end of 6 hr pO2 was 243.5 +/- 61.5 vs. 71.7 +/- 10.2 mmHg (P less than 0.02) for the controls. A-aDO2 was less in the BN 52021 groups: 431.8 +/- 58.3 vs. 606.0 +/- 9.8 mmHg in the control groups (P less than 0.001), and PVR was significantly less in the BN 52021 group: 346 +/- 70.8 vs. 663 +/- 64.3 dynes/sec/cm-5 (P less than 0.035). We conclude that PAF antagonists like BN 52021 may be useful adjuncts for lung preservation. The effects of BN 52021 are easily explained by PAF antagonist activity in ischemic and reperfusion-induced pulmonary dysfunction. However this study does not exclude that BN 52021 may have direct effects.     

Platelet-activating factor antagonists do not attenuate delayed posttraumatic cerebral edema in rats

Platelet-activating factor (PAF) receptor antagonists reportedly improve early postischemic neurological recovery and cerebral blood flow in selected experimental models. Their effects on posttraumatic cerebral edema have, however, not been examined. In a rat model of right hemispheric percussive cerebral trauma, we examined the effects of two PAF receptor antagonists on posttraumatic edema formation. Two groups of rats received either BN 52021 (n = 14) or WEB 2086 (n = 11), 10 mg/kg i.v. at 15 min posttrauma. Two other groups treated with the BN 52021 (n = 17) and WEB 2086 (n = 10) vehicles served as controls. Hemispheric percent brain water was determined at 24 h. Edema occurred in all groups. Neither PAF receptor antagonist significantly reduced right hemispheric percent brain water (81.08 +/- 0.25 and 81.04 +/- 0.15 in Bn 52021 and WEB 2086-treated rats, respectively, versus 81.31 +/- 0.23 and 81.14 +/- 0.17% brain water in BN 52021 vehicle and WEB 2086 vehicle-treated rats). Mortality was not statistically different between groups. These data do not support a major role for PAF in the development of posttraumatic cerebral edema.     

The effect of prednisolone, thromboxane, and platelet-activating factor receptor antagonists on lymphocyte and platelet migration in experimental cardiac transplantation

Three agents that significantly prolong cardiac allograft survival were tested in Lewis rats that were recipients of hearts from Lewis X Brown-Norway F1 hybrid donors. In the presence of azathioprine, the effects of daily administration of either the thromboxane antagonist (L 640,035), the platelet-activating factor (PAF) antagonist (BN 52021) or prednisolone were evaluated on the infiltration of cardiac allografts by syngeneic lymphocytes and platelets labeled with 111indium. As anticipated, platelet deposition was reduced by the thromboxane antagonist and unaffected by the PAF antagonist; the latter is likely due to the known absence of PAF receptors in rat platelets. In addition prednisolone had no effect. The increased accumulation of lymphocytes on days 4-5 was also unaffected by all three drugs. These experiments indicate that, in this model, graft survival is not necessarily related to lymphocyte and platelet infiltration of the graft. The data also provide evidence for the efficacy of the thromboxane receptor antagonist L 640,035 in preventing platelet deposition in vivo.     

血小板激活因子在急性重症胰腺炎发 病过程中作用的实验研究

作者为探讨血小板激活因子在狗急性重症胰腺炎发病过程中的作用，采用１７只比格（Ｂｅａ－ｇｌｅ）狗，随机分为三组：对照组（ｎ＝５）、胰腺炎组（ｎ＝６）、治疗组（ｎ＝６）。胰腺炎组及治疗组动物制成急性重症胰腺炎动物模型。治疗组动物在模型复制后５ｍｉｎ，３ｈ分别静脉注射血小板激活因子（ＰＡＦ）拮抗剂ＢＮ５２０２１（５ｍｇ／ｋｇ）。用温氏法测定血清淀粉酶活性，血小板聚集法测定血清及胰腺组织中ＰＡＦ的含量。结果显示：急性重症胰腺炎模型复制成功后３０ｍｉｎ，胰腺炎组血清淀粉酶活性即上升到基础值的２００±４４．７％，８ｈ高达４６６．７±１１１．６％。８ｈ时与对照组、治疗组差异均有显著性意义（Ｐ＜０．０５）。胰腺炎组血中ＰＡＦ含量在３０ｍｉｎ时即开始上升，８ｈ达最高１１．８１±０．７８ｎｇ／ｍｌ，在３０ｍｉｎ之后与对照组比较即差异有非常显著的意义（Ｐ＜０．０１），而１ｈ之后与治疗组差异有非常显著的意义（Ｐ＜０．０１）。胰腺组织中ＰＡＦ含量，胰腺炎组比治疗组及对照组明显增高（Ｐ＜０．０１）。作者认为ＰＡＦ在急性重症胰腺炎的发病过程中起重要作用，ＰＡＦ拮抗剂有希望成为治疗急性重症胰腺炎的有效药物。     

血小板活化因子及其受体对颈髓损伤后血脊髓屏障损害的分子机制研究

目的：探讨血小板活化因子（ＰＡＦ）及其受体对颈髓损伤后血脊髓屏障损害的分子机制。方法：采用蛛网膜下腔注射ＰＡＦ及静脉注射ＰＡＦ受体拮抗剂ＢＮ５２０２１，应用地高辛标记ｃＤＮＡ探针原位杂交技术检测颈髓损伤后颈髓血管内皮细胞细胞间粘附分子－１ｍＲＮＡ（ＩＣＡＭ－１ｍＲＮＡ）和内皮细胞白细胞粘附分子－１ｍＲＮＡ（ＥＬＡＭ－１ｍＲＮＡ）表达。观察ＰＡＦ及其受体拮抗剂对颈髓损伤后血脊髓屏障、ＩＣＡＭ－１ｍＲＮＡ、ＥＬＡＭ－１ｍＲＮＡ表达的影响。结果：伤后颈髓血管内皮细胞ＩＣＡＭ－１ｍＲＮＡ、ＥＬＡＭ－１ｍＲＮＡ表达、伊文思蓝含量、水含量呈不同程度的增加；ＰＡＦ可使伤后血管内皮细胞ＩＣＡＭ－１ｍＲＮＡ、ＥＬＡＭ－１ｍＲＮＡ表达、伊文思蓝含量、水含量增加更为显著，ＰＡＦ受体拮抗剂可抑制ＩＣＡＭ－１ｍＲＮＡ、ＥＬＡＭ－１ｍＲＮＡ表达，降低颈髓组织伊文思蓝含量及水含量。结论：ＰＡＦ通过增加伤后颈髓血管内皮细胞粘附分子的表达是导致血脊髓屏障损害的重要分子基础。ＰＡＦ受体对伤后血管内皮细胞细胞粘附分子的表达具有调控作用。     

Beneficial effects of recombinant platelet-activating factor acetylhydrolase and BN 52021 on bacterial translocation in cerulein-induced pancreatitis

BACKGROUND: Bacterial translocation (BT) has been suggested to be responsible for the high incidence of infections occurring after acute pancreatitis (AP). The aim of this study was to investigate the effects of the platelet-activating factor (PAF) inactivator, recombinant PAF-acetylhydrolase (rPAF-AH), and the PAF receptor antagonist, BN 52021, in AP. METHODS: Forty-eight male Wistar rats were divided into 4 groups: the sham group received saline intraperitoneally every hour for 6 h; the control group received cerulein 50 g/kg i.p. every hour for 6 h; the rPAF-AH group received AP plus rPAF-AH (5 mg/kg i.v. bolus), and the BN52021 group received AP plus BN 52021 (5 mg/kg i.v. bolus). The animals were sacrificed 12 h after the first cerulein injection. RESULTS: Supramaximal cerulein stimulation induced an increase in serum pancreatic enzymes, interleukin (IL)-6, pancreatic edema, and produced histologic evidence of AP. Compared with the control group, the addition of PAF receptor antagonists had a significant effect on serum pancreatic enzymes, pancreatic edema, and the histologic score of the pancreatitis. AP caused significant increases in BT in mesenteric lymph nodes (MLNs), pancreas, liver, spleen and blood. Compared with the control group, both rPAF-AH and BN 52021 decreased BT in the pancreas and blood. In addition, rPAF-AH decreased BT in the MLNs. We also found that PAF receptor antagonists suppressed the elevation in IL-6 levels. CONCLUSION: PAF antagonists attenuated the severity of experimental AP and reduced pancreatitis-induced BT to distant sites.     

血小板活化因子在烧伤合并内毒素血症早期肺损伤中的作 …

目的 探讨血小板活化因子（ＰＡＦ）肿瘤坏死因子（ＴＮＦ）等在烧伤合并内毒素血症早期肺损伤中的作用及意义。方法 采用２０％ＴＢＳＡⅢ度烧伤合并内毒素注射复制大鼠早期肺损伤模型,检测血浆ＰＡＦ、ＴＮＦ含量等,观察肺组织病理形态学变化并应用ＰＡＦ受体拮抗剂防治早期肺损伤。结果 ＰＡＦ是烧伤合并内毒素血症早期先于ＴＮＦ出现变化的炎症介质,血浆ＰＡＦ浓度与早期肺操作程度呈正相关,注射ＰＡＦ受体拮抗剂ＢＮ５０     

Impact of PAF antagonist BN 52021 (Ginkolide B) on post-ischemic graft function in clinical lung transplantation.

BACKGROUND: Platelet activating factor (PAF) is associated with ischemia/reperfusion injury (I/R) after lung transplantation. Following promising experimental results, this prospective trial investigated the potential effect of PAF antagonist BN 52021 (ginkolide B) on clinical Euro-Collins (EC)-based lung preservation. METHODS: We analyzed 8 double-lung transplant patients in each of 3 groups. In the low-dose group (LDG), donor lungs were perfused with EC containing 2 mg/kg BN 52021, whereas we used 10 mg/kg in the high-dose group (HDG) and placebo in the control group (CG). Before reperfusing the first lung, we administered intravenously 120 mg BN 52021 (LDG), 600 mg BN 52021 (HDG), or placebo (CG). Hemodynamics in terms of pulmonary arterial pressure, pulmonary vascular resistance and serial determinations of the alveolo-arterial oxygen difference (AaDO(2)) were recorded. We measured blood levels of PAF pre-operatively and post-operatively, after 10 minutes and after 3, 8, 24, 48, and 144 hours. RESULTS: Within 32 hours, we noted a tendency toward better AaDO(2) in the LDG and the HDG compared with the CG (p > 0.05). We observed a significant improvement of AaDO(2) after 3 hours (HDG, p = 0.033) and 8 hours (LDG, p = 0.024), with poorest values in the CG. The PAF concentrations were lowest in the HDG, with significant deterioration 10 minutes after reperfusion. In contrast, placebo led to higher PAF levels. We measured significantly lower PAF concentrations (HDG vs CG) at 10 minutes and at 6 days post-operatively. CONCLUSIONS: Use of high-dose PAF antagonist BN 52021 can easily be combined with clinical preservation methods and may help optimize pulmonary function with reduced PAF levels, in the early post-ischemic period.     

Protective effect of the PAF antagonist BN 52021 in an experimental renal warm ischemia model

Platelet activating factor is involved in warm ischemic damage. We studied the effect of the PAF receptor antagonist BN 52021 in an experimental model of 60 min of renal warm ischemia in which the left kidney was flushed with Euro-Collins solution and a right nephrectomy was performed. Eighty Wistar rats were divided into a sham-operated group, two control groups, and four study groups, according to the dosage and route of BN 52021 administration. BN 52021 was used in the flush solution at concentrations of 0.1 and 0.5 mg/ml, or intravenously prior to ischemia at 5 and 10 mg/kg body weight. Creatinine clearance per, 100g body weight, fractional sodium excretion, and conventional histology were studied. Rats that received BN 52021 intravenously showed a significantly higher creatinine clearance than controls. Intravenous BN 52021 produced a higher acceleration of renal function recovery at 10 mg/kg than at 5 mg/kg body weight. Conventional histology was better in animals that received BN 52021 at 10 mg/kg body weight than in controls. Addition of BN 52021 to Euro-Collins flushing solution showed no protective effect. We conclude that intravenous BN 52021 shows a renal protective effect against warm ischemia.     

Prevention of cyclosporin nephrotoxicity with a platelet-activating factor (PAF) antagonist

BACKGROUND.: Cyclosporin (CsA) is a potent immunosuppressive drug whose mainside-effect is nephrotoxicity. In the kidney, CsA induces vasoconstrictionwith a decrease in renal blood flow (RBF) and glomerular filtrationrate (GFR) and a significant increase in renal vascular resistance(RVR). CsA enhances platelet-activating factor (PAF) synthesisin mesangial cells in vitro. PAF, a secondary mediator of anaphylaxisand inflammation, exhibits vasoactive properties in the kidneysimilar to those of CsA. METHODS.: The in situ autoperfused rat kidney model was used to investigatewhether PAF plays a role in the haemodynamic injury inducedby CsA. RESULTS.: In this model, CsA (40 mg/kg and 20 mg/kg i.v.) induced a significantdecrease in RBF and in GFR and an increase in RVR. BN 52021,a potent and specific PAF antagonist (20 mg/kg i.v. bolus dose)induced a significant increase in GFR (137±32% of initialvalue, P<0.05). BN 52021 (20 and 10 mg/kg) also significantlyprevented the decline in RBF and GFR induced by CsA. CONCLUSIONS.: We have demonstrated that the PAF antagonist BN 52021 can minimizethe alteration of renal function induced by CsA.     

Platelet-activating factor antagonist, BN-52021 protects against cis-diamminedichloroplatinum nephrotoxicity in the rat

The protective effect of the platelet-activating factor (PAF) antagonist, BN 52021, was assessed on cis-diammine-dichloroplatinum (CDDP)-induced nephrotoxicity. Wistar male rats were treated with either a single dose of CDDP (10 mg/kg b.w. ip) alone or in association with 7 daily doses of BN 52021 (10 mg/kg b.w. ip). At the end of the experiment, the CDDP-treated rats lost 25% of body weight and serum creatinine and urea increased from 0.041 +/- 0.006 mmol/l and 0.165 +/- 0.007 g/l for the control group to 0.202 +/- 0.019 mmol/l and 1.51 +/- 0.131 g/l versus CDDP respectively. Body weight, serum creatinine, serum urea and creatinine clearances were similar to the control group in animals treated with CDDP and BN 52021. CDDP caused proximal tubular necrosis and dilatation of cortical collecting tubes, changes that were markedly less in the BN 52021-protected animals. The concomitant administration of BN 52021 with CDDP did not modify the plasma pharmacokinetic of CDDP. In addition, BN 52021 did not interfere with the antiproliferative and antitumoral actions of CDDP in cultured human tumor cells. BN 52021 therefore could prevent the nephrotoxicity of CDDP.     

Effect of platelet-activating factor antagonist on cyclosporine nephrotoxicity. Glomerular hemodynamics evaluation

In order to evaluate the effect of platelet-activating factor (PAF) antagonist BN 52021 (5 mg/kg i.v.) on cyclosporine (50 mg/kg i.v.) nephrotoxicity, euvolemic Munich-Wistar rats were submitted to micropuncture studies. BN 52021 alone did not change the total (1.08 +/- 0.07 vs. 1.04 +/- 0.06 ml/min) or single nephron (SN) (29.1 +/- 50 vs. 31.3 +/- 4.0 nl/min) and glomerular filtration rate. The CsA administration caused a decline on GFR (0.47 +/- 0.07 vs. 0.96 +/- 0.04 ml/min, P less than 0.05) and on SNGFR (14.0 +/- 3.5 vs. 27.9 +/- 3.4 ml/min, P less than 0.05). An increase in afferent (RA) and efferent (RE) arteriolar resistances, 180% and 360%, respectively, that caused a decrease on glomerular plasma flow rate (QA) from 100.99 +/- 17.09 to 44.37 +/- 13.37 nl/min (P less than 0.05) was observed. Moreover, the glomerular ultrafiltration coefficient (Kf) declined by 70% (0.096 +/- 0.003 to 0.031 +/- 0.10 ml/sec mmHg, P less than 0.05). The previous BN 52021 administration on rats treated with CsA blunted its effects on superficial nephrons. The SNGFR (22.3 +/- 3.0 vs. 28.0 +/- 25 nl/min), QA (72.2 +/- 5.9 vs. 91.7 +/- 12.1 nl/min) and KF (0.038 +/- 0.009 vs. 0.048 +/- 0.005 nl/s mmHg) remained unaltered. By contrast, the total renal function was not prevented by BN 52021 treatment: GFR 0.45 +/- 0.12 vs. 0.94 +/- 0.05 ml/min (P less than 0.05). Thus, this study suggests that PAF may participate in CsA nephrotoxicity. Furthermore, the protective effect of BN 52021 on superficial nephrons may indicate that BN 52021 is a drug that can minimize the impairment of renal function induced by CsA.     

Platelet-Activating Factor Antagonist,BN-52021 Protects Against Cis-Diamminedichl or Oplatinum Nephrotoxicity in the Rat

The protective effect of the platelet-activating factor (PAF) antagonist, BN 52021, was assessed on cis-diammine-dichloroplatinum (CDDP)-induced nephrotoxicity. Wistar male rats were treated with either a single dose of CDDP (10 mg/kg b.w. ip) alone or in association with 7 daily doses of BN 52021 (10 mg/kg b.w. ip). At the end of the experiment, the CDDP-treated rats lost 25% of body weight and serum creatinine and urea increased from 0.041±0.006 mmol/1 and 0.165±0.007 g/1 for the control group to 0.202±0.019 mmol/1 and 1.51±0.131 g/1 versus CDDP respectively. Body weight, serum creatinine, serum urea and creatinine clearances were similar to the control group in animals treated with CDDP and BN 52021. CDDP caused proximal tubular necrosis and dilatation of cortical collecting tubes, changes that were markedly less in the BN 52021-protected animals. The concomitant administration of BN 52021 with CDDP did not modify the plasma pharmacokinetic of CDDP. In addition, BN 52021 did not interfere with the antiproliferative and antitumoral actions of CDDP in cultured human tumor cells. BN 52021 therefore could prevent the nephrotoxicity of CDDP.     

Involvement of lipid mediators in the pathogenesis of experimental nephrosis in rats: its pharmacological modulation.

The administration of a single-injection of Adriamycin (ADR) to rats results in marked proteinuria and glomerular morphological changes that are similar to minimal change disease in humans. We have hypothesized that Adriamycin, by itself or through the release of some mediators from resident glomerular cells, could provoke a damage to epithelial glomerular cells. Sprague-Dawley rats received a single injection of Adriamycin, 7.5 mg/kg bw, allocated randomly in several groups and treated throughout 2 weeks of follow-up. All control nontreated animals developed important nephrotic syndrome and degenerative lesions of epithelial glomerular cells. Isolated glomeruli from animals injected with adriamycin 14 days before synthesized thromboxane (TxB2) and platelet activating factor (PAF) in amounts above the rates of control glomeruli. Animals treated with three structurally different PAF receptor antagonists did not present proteinuria or only to a very low extent (p less than 0.0005). In these rats no alterations in epithelial cells were noted. Furthermore, no significant changes in the TxB2 production were noted in rats treated with BN 52021, a PAF receptor antagonist. Leukotrienes also seem to participate since treatment with a 5-lipoxygenase inhibitor partially corrected proteinuria. Moreover, glomeruli from animals with nephrosis and treated with this compound presented only a discrete reduction in the PAF synthesis. On the whole, these data suggest a key role for PAF in the pathogenesis of adriamycin nephropathy. Other lipid meditors, released in cascade simultaneously or thereafter, could perpetuate the renal damage.     

Role of platelet activating factor in gentamicin and cisplatin nephrotoxicity.

The present study was undertaken to evaluate the effects of platelet activating factor (PAF) antagonists on nephrotoxicity induced by gentamicin (GENTA) and cisplatin (DDP) in rats. PAF infusion provoked a 56% decline in single nephron (SN) GFR due to a decrease in glomerular plasma flow (QA, 55%), glomerular transcapillary hydraulic pressure (delta P, 13%), and glomerular ultrafiltration coefficient (Kf, 37%). Four days after a single dose of DDP (6 mg/kg, i.p.) we observed non-oliguric acute renal failure (ARF) with reduced SNGFR (45%), QA (46%) and delta P (10%) and unchanged Kf. GENTA administration for 10 days (40 mg/kg, i.p. daily) induced a decline in SNGFR (40%), QA (41%) and Kf (41%). Chronic treatment with a GENTA + PAF antagonist (BN 52021) partially prevented the decline in SNGFR (22%) by an amelioration in QA (25%) and Kf (13%). However, simultaneous treatment with DDP and BN 52063 completely prevented the ARF induced by DDP, normalizing all parameters of renal function. Thus, PAF may be a potential mediator involved in the nephrotoxicity induced by GENTA and DDP.     

Involvement of Lipid Mediators in the Pathogenesis of Experimental Nephrosis in Rats: Its Pharmacological Modulation

The administration of a single-injection of Adriamycin (ADR) to rats results in marked proteinuria and glomerular morphological changes that are similar to minimal change disease in humans. We have hypothesized that Adriamycin, by itself or through the release of some mediators from resident glomerular cells, could provoke a damage to epithelial glomerular cells. Sprague-Dawley rats received a single injection of Adriamycin, 7.5 mg/kg bw, allocated randomly in several groups and treated throughout 2 weeks of follow-up. All control nontreated animals developed important nephrotic syndrome and degenerative lesions of epithelial glomerular cells. Isolated glomeruli from animals injected with adriamycin 14 days before synthesized tromboxane (TxB2) and platelet activating factor (PAF) in amounts above the rates of control glomeruli. Animals treated with three structurally different PAF receptor antagonists did not present proteinuria or only to a very low extent (p < 0.0005). In these rats no alterations in epithelial cells were noted. Furthermore, no significant changes in the TxB2 production were noted in rats treated with BN 52021, a PAF receptor antagonist. Leukotrienes also seem to participate since treatment with a 5-lipoxygenase inhibitor partially corrected proteinuria. Moreover, glomeruli from animals with nephrosis and treated with this compound presented only a discrete reduction in the PAF synthesis. On the whole, these data suggest a key role for PAF in the pathogenesis of adriamycin nephropathy. Other lipid meditors, released in cascade simultaneously or thereafter, could perpetuate the renal damage.     

Actions of cyclosporin A on cultured rat mesangial cells

The effects of cyclosporin A (CsA) on planar surface area of cultured rat mesangial cells (PCSA) and cross-sectional area of isolated rat glomeruli (GCSA) were tested. The same experiments were performed after preincubation with platelet activating factor (PAF) antagonists (BN 52021, alprazolam) or calcium channel blockers (verapamil). Areas of cells or glomeruli were analyzed by a computer-assisted method. CsA reduced PCSA in a time-dependent (significant effects began at 15 min, about 12% of reduction with 10(-6) M CsA) and dose-dependent (no effect at 10(-9) M CsA, maximal reduction of about 30% at 60 min of incubation with 10(-7) M CsA) fashion. BN 52021 (5.10(-5) M) and alprazolam (10(-5) M) completely inhibited the reduction of mesangial cell area induced by CsA. Verapamil (10(-5) M) only partially inhibited this action. Glomerular cross-sectional area decreased after 30 minutes of incubation with 10(-6) M CsA (1.45 +/- 0.02 vs. 1.55 +/- 0.02 m2.10(-8), P less than 0.001), an effect that was inhibited by BN 52021 or verapamil. In addition, 10(-6) M CsA increased PAF production by isolated rat glomeruli (425 +/- 80 pg/mg vs. 198 +/- 13 pg/mg in control glomeruli, P less than 0.01), an effect which was not inhibited by verapamil. These results suggest that CsA could reduce GFR by decreasing the glomerular ultrafiltration coefficient, perhaps as a consequence of the contraction of mesangial cells. PAF seems to play a pivotal role in the genesis of this action.     

The roles of platelet-activating factor and endothelin-1 in renal damage after total hepatic ischemia and reperfusion

BACKGROUND: This study was designed to verify the involvement of platelet-activating factor (PAF) in renal damage associated with hepatic ischemia and reperfusion (HIR) injury through the release of endothelin (ET)-1 and to determine the modulating effect of a specific PAF receptor antagonist on these insults in rats. METHODS: Male rats pretreated with either normal saline as a vehicle (NS group) or intravenous TCV-309, a PAF receptor antagonist (TCV group), were subjected to 120 min of total hepatic ischemia under an extracorporeal portosystemic shunt. Plasma aspartate transaminase, creatinine, blood urea nitrogen, and ET-1 levels and the relative renal wet weight were determined under nonischemic conditions and at 1, 3, and 6 hr of reperfusion after hepatic ischemia. Changes in mean arterial blood pressure and renal tissue blood flow measurements in the kidney were determined throughout the experiment. RESULTS: Increased plasma aspartate transaminase, creatinine, blood urea nitrogen, and ET-1 levels and the relative renal wet weight after HIR in the NS group were significantly suppressed by TCV-309 pretreatment. Mean arterial blood pressure and renal tissue blood flow after HIR in the TCV group were significantly improved when compared with those in the NS group. These effects resulted in attenuation of structural hepatic and renal damage with the improvement of 7-day survival (62%). CONCLUSIONS: The present study demonstrates that renal damage as well as critical liver injury is produced after reperfusion following 120 min of total hepatic ischemia. A PAF receptor antagonist may be therapeutically useful to protect against these types of damage via indirect modulation of plasma ET-1 levels.     

Tumor necrosis factor-induced mortality is reversed with cyclooxygenase inhibition.

OBJECTIVE: The authors hypothesized that TNF would induce eicosanoid synthesis, and a cyclooxygenase inhibitor would attenuate both eicosanoid synthesis and improve survival in an LD90 TNF-induced (150 ng/kg/i.v./5 min) mortality model. SUMMARY BACKGROUND DATA: Tumor necrosis factor is a cardinal mediator in sepsis; however, little is known about its effects on arachidonate metabolism. METHODS: Conscious male rats with carotid arterial and jugular venous catheters were randomized for mortality: group I, TNF alone (150 kg/i.v./15 min, n = 30); group II, ibuprofen (30 mg/kg/i.v. at t = -20 and +240 min), plus TNF, (n = 28); and for hemodynamics, eicosanoid synthesis, blood gases: group III, TNF alone, (n = 8); group IV, ibuprofen + TNF (n = 8); group V, monoclonal antibody to TNF plus TNF (n = 8). Mortality was determined at 4-72 hr. Other parameters determined over 4 hours (0, 5, 60, 120, 240 min). RESULTS: TNF stimulated synthesis of (a) TXB2 (71 +/- 30 pg/ml, mean +/- SE at base vs. 117 +/- 18 at 4 hr, p < 0.02); (b) PGE2 (70 +/- 6 pg/ml at base vs. 231 +/- 68 at 4 hr, p < 0.02); (c) 6PGF (52 +/- 6 pg/ml at base vs. 250 +/- 80 at 4 hr, p < 0.02). Ibuprofen significantly (p < 0.05) inhibited eicosanoid synthesis from TNF. TNF-induced mortality (87%, 26/30) was dramatically decreased with ibuprofen (11%, 3/28), at 4, 24, and 72 hr (p < 0.01). Monoclonal antibody to TNF prevented all abnormalities and had 100% survival. Hemodynamic events were similar in both groups, but metabolic acidosis was attenuated with ibuprofen. CONCLUSIONS: TNF stimulates arachidonic acid metabolism in vivo. A cyclooxygenase inhibitor attenuates eicosanoid synthesis and dramatically improves survival. TNF appears to have different effect on tissues that synthesize certain eicosanoids. Hypotension from TNF is not mediated via the eicosanoids. TNF-induced mortality, like endotoxemia/sepsis may be mediated, in part, via arachidonic acid metabolites. These new findings support the notion that cyclooxygenase inhibitors may be used as adjunctive therapy in clinical sepsis.