• The Korean Journal of Physiology and Pharmacology
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• 제4권3호
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• pp.219-226
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• 2000

In order to elucidate the role of platelet activating factor (PAF) in the acute lung injury induced by endotoxin (ETX), activities of phospholipase A2, lyso PAF acetyltransferase and oxidative stress by neutrophilic respiratory burst were probed in the present study. To induce acute lung injury, $100\;{\mu}g$ of E.coli ETX (type 0127; B8) was instilled directly into the tracheae of Sprague-Dawley rats. Five hours after the ETX instillation, induction of acute lung injury was confirmed by lung leak index and protein contents in the bronchoalveolar lavage (BAL) fluid. At the same time, lung phospholipase A2 (PLA2) activity and expression of group I and II secretory type PLA2 were examined. In these acutely injured rats, ketotifen fumarate, known as lyso PAF acetyltransferase inhibitor and mepacrine were administered to examine the role of PAF in the pathogenesis of the acute lung injury. To know the effect of the ETX in the synthesis of the PAF in the lungs, lyso PAF acetyltransferase activity and PAF content in the lungs were measured after treatments of ETX, ketotifen fumarate and mepacrine. In addition, the role of neutrophils causing the oxidative stress after ETX was examined by measuring lung myeloperoxidase (MPO) and enumerating neutrophils in the BAL fluid. To confirm the oxidative stress in the lungs, pulmonary contents of malondialdehyde (MDA) were measured. After instillation of the ETX in the lungs, lung leak index increased dramatically (p＜0.001), whereas mepacrine and ketotifen decreased the lung leak index significantly (p＜0.001). Lung PLA2 activity also increased (p＜0.001) after ETX treatment compared with control, which was reversed by mepacrine and ketotifen (p＜0.001). In the examination of expression of group I and II secretory PLA2, mRNA synthesis of the group II PLA2 was enhanced by ETX treatment, whereas ketotifen and WEB 2086, the PAF receptor antagonist, decreased the expression. The activity of the lysoPAF acetyltransferase increased (p＜0.001) after treatment of ETX, which implies the increased synthesis of PAF by the remodelling of lysoPAF in the lungs. Consequently, the contents of the PAF in the lungs were increased by ETX compared with control (p＜0.001), while mepacrine (p＜0.001) and ketotifen (p＜0.01) decreased the synthesis of the PAF in the lungs of ETX treated rats. The infiltration of the neutrophils was confirmed by measuring and enumerating lung MPO and the neutrophils in the BAL fluid respectively. Compared with control, ETX increased lung MPO and number of neutrophils in BAL significantly (p＜0.001) whereas mepacrine and ketotifen decrerased number of neutrophils (p＜0.001) and MPO (p＜0.05, p＜0.001, respectively). The lung MDA contents were also increased (p＜0.001) by ETX treatment, but treatment with mepacrine (p＜0.001) and ketotifen (p＜0.01) decreased the lung MDA contents. Collectively, we conclude that ETX increases PLA2 activity, and that the subsequently increased production of PAF was ensued by the remodelling of the lyso PAF resulting in tissue injury by means of oxidative stress in the lungs.

• Archives of Pharmacal Research
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• 제21권6호
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• pp.774-778
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• 1998

Brazilin [7,11b-dihydrobenz[b]indeno[1,2-d]pyran-3,6a,9,10(6H)-tetrol] inhibited thrombin-, collagen- and ADP-induced aggregation of washed rat platelets. T hrombin- and collagen-induced ATP release were also inhibited by brazilin in a concentration-dependent manner. Brazilin inhibited the formation of platelet thromboxane $A_2$ caused by thrombin, whereas it had no effect on the prostaglandin $D_2$ formation. Brazilin inhibited $^3H$-arachidonic acid liberation from membrane phospholipids of thrombin-stimulated platelets. Brazilin inhibited the rise of intracellular free calcium caused by thrombin. These results indicate that the inhibition of phospholipase ($PLA_2$) activity and [$[Ca^{2+}]_1$ elevation might be at least a part of antiplatelet mechanism of brazilin.

• 생명과학회지
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• 제16권1호
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• pp.17-21
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• 2006

The effects of Korean and Japanese radishes on inflammatory reaction that involves arachidonic acid cascades were investigated in human epithelial gastric cell. The activities of type I (porcine pancreas) and type II (Crotalus atrox) phospholipase $A_2(PLA_2$) were inhibited by radish. Cyclooxygenase-2 (COX-2) activity was significantly suppressed by radish (p<0.05, p<0.01 and p<0.005). The nitric oxide production was also inhibited by radish. The Korean radish was more effective in inhibition of $PLA_2$ and COX-2 activities and nitric oxide production than Japanease radish. These results indicate that radish has a protective effect on gastric epithelial cell inflammation by suppressing the activities of $PLA_2$ and COX-2 activities and nitric oxide production from gastric epithelial cell.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
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• pp.193.2-194
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• 2003

Effect of phenylpropanoids on Phospholipase A2 (PLA2) and phosphodiesterase (PDE) activities in the asthmatic lung tissue were studied in guinea pigs. Bronchial asthma were introduced by the challenge of aerosolized ovalbumin (OA) in the double-chambered plethysmograph at twenty one days after sensitization of OA in guinea pigs. Bronchoalveolar lavage fluids (BALF) were taken by brochalveolar lavage with HEPES buffer. (omitted)

• BMB Reports
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• 제41권8호
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• pp.555-559
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• 2008

Reactive oxygen species (ROS) are generated in mammalian cells via both enzymatic and non-enzymatic mechanisms. Although certain ROS production pathways are required for the performance of specific physiological functions, excessive ROS generation is harmful, and has been implicated in the pathogenesis of a number of diseases. Among the ROS-producing enzymes, NADPH oxidase is widely distributed among mammalian cells, and is a crucial source of ROS for physiological and pathological processes. Reactive oxygen species are also generated by arachidonic acid (AA) metabolites, which are released from membrane phospholipids via the activity of cytosolic phospholipase $A_2$ ($cPLA_2$). In this study, we describe recent studies concerning the generation of ROS by AA metabolites. In particular, we have focused on the manner in which AA metabolism via lipoxygenase (LOX) and LOX metabolites contributes to ROS generation. By elucidating the signaling mechanisms that link LOX and LOX metabolites to ROS, we hope to shed light on the variety of physiological and pathological mechanisms associated with LOX metabolism.

• 한국응용과학기술학회지
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• 제16권3호
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• pp.263-271
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• 1999

We checked the presence of phospholipase $A_2(PLA)_2$ which could split the ester bond at the position 2 in the glycerol backbone of glycerophospholipids, in the cells of hyperthermophiles of Pyrococcus horikoshii and Sulfolobus acidocaldarius. The results obtained are as follows; (1). Pyrococcus horikoshii cells were grown in obligate anaerobic conditions at $95^{\circ}C$ and they needed sulfur as energy source instead of oxygen, while Sulfolobus acidocaldarius species grew well in the aerobic medium (pH 2.5) containing yeast and sucrose at $75^{\circ}C$. (2). Pyrococcus horikoshii cells produced phospholipase $A_2$ in the cell culture media although this species did not show lipase activity at least in the pH range of 1.5 ${\sim}$ 3.5. Sulfolobus acidocaldarius cells produced lipase hydrolyzing triacylglycerols such as triolein, but did not split any kind of phospholipids used as substates. (3). The compound of 1-decanoyl-2-(p-nitrophenylglutaryl) phosphatidylcholine was not suitable for a substrate in this experiment, though frequently used as a subtrate for checking presence of phospholipase $A_2$, for its decomposi-tion in this experiment. The L-${\alpha}$-phosphatidylcholine-${\beta}$-[N-7-nitrobenz-2-oxa-1, 3-diazol]aminohexanoyl-${\gamma}$-hexadecanoyl labelled with a fluorescent material, did not show any migration of acyl chains in the molecule during the reaction with phospholipase $A_2$ under a hot condition. (4). Phospholipase $A_2$ in the cells of Pyrococcus horikoshii, showed the optimum activity at $pH6.7{\sim}7.2$ and $95{\sim}105^{\circ}C$, respectively, and was activated by addition of calcium chloride solution. Andthe phospholipase $A_2$ specifically hydrolyzed glycero-phospholipids such as phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl serine and phosphatidyl inositol, but could not split phospholipid containing ether bonds in the molecule such as DL -${\alpha}$-phosphatidylcholine-${\beta}$-palmitoyl-${\gamma}$-O-hexadecyl, DL-${\alpha}$-phosphati- dylcholine-${\beta}$- oleoyl-${\gamma}$-O-hexadecyl, DL-phosphatidylcholine-dihexadecyl.

• The Korean Journal of Physiology and Pharmacology
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• 제3권1호
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• pp.93-100
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• 1999

The present study was designed to assess the roles of $PLA_2$ activation and arachidonic acid (AA) metabolites in hypoxia-induced renal cell injury. Hypoxia increased LDH release in a dose-dependent manner in rabbit renal cortical slices, and this increase was significant after 20-min hypoxia. The hypoxia-induced LDH release was prevented by amino acids, glycine and alanine, and extracellular acidosis (pH 6.0). Buffering intracellular $Ca^{2+}$ by a chelator, but not omission of $Ca^{2+}$ in the medium produced a significant reduction in hypoxia-induced LDH release. The effect of hypoxia was blocked by $PLA_2$ inhibitors, mepacrine, butacaine, and dibucaine. A similar effect was observed by a 85-kD $cPLA_2$ inhibitor $AACOCF_3.$ AA increased hypoxia-induced LDH release, and albumin, a fatty acid absorbent, prevented the LDH release, suggesting that free fatty acids are involved in hypoxia-induced cell injury. These results suggest that $PLA_2$ activation and its metabolic products play important roles in pathogenesis of hypoxia-induced cell injury in rabbit renal cortical slices.

• Journal of Ginseng Research
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• 제39권3호
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• pp.189-198
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• 2015

Background: Antiallergic effect of 20(S)-protopanaxatriol (PPT), an intestinal metabolite of ginseng saponins, was investigated in guinea pig lung mast cells and mouse bone marrow-derived mast cells activated by a specific antigen/antibody reaction. Methods: Increasing concentrations of PPT were pretreated 5 min prior to antigen stimulation, and various inflammatory mediator releases and their relevant cellular signaling events were measured in those cells. Results: PPT dose-dependently reduced the release of histamine and leukotrienes in both types of mast cells. Especially, in activated bone marrow-derived mast cells, PPT inhibited the expression of Syk protein, cytokine mRNA, cyclooxygenase-1/2, and phospholipase $A_2$ ($PLA_2$), as well as the activities of various protein kinase C isoforms, mitogen-activated protein kinases, $PLA_2$, and transcription factors (nuclear factor-${\kappa}B$ and activator protein-1). Conclusion: PPT reduces the release of inflammatory mediators via inhibiting multiple cellular signaling pathways comprising the $Ca^{2+}$ influx, protein kinase C, and $PLA_2$, which are propagated by Syk activation upon allergic stimulation of mast cells.

• Tuberculosis and Respiratory Diseases
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• 제54권5호
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• pp.532-541
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• 2003

연구배경 : 장의 재관류로 발생하는 급성폐손상에서 group II $PLA_2$의 억제제로 알려진 doxycyclin의 치료효과와 그 작용기전을 알아보기 위하여 본 연구를 시행하였다. 특히 장의 재관류에 의한 급성폐손상이 호중구에 의한 산화성 스트레스에 의하며 이 과정에서 group II $PLA_2$가 관여한다는 사실에 근거하여 doxycyclin의 산화성 스트레스억제를 확인하는 것이 본 연구의 목적이었다. 방법 : 체중 300g 내외의 Sprague-Dawley 흰쥐에서 상장간막동맥을 60분간 clamp한 뒤 120분간의 재관류를 시키면 급성폐손상이 유도된다. 이때 호중구에 의한 산화성스트레스가 유발되고 여기에 $PLA_2$가 관여하는 것을 관찰하기위해 lung leak, lung MPO 활성도, CeCl3 cytochemical electron microscopy, cytochrome-c reduction assay 및 lung $PLA_2$ 활성도를 측정하였다. 또한 doxycyclin의 효과를 확인하기 위하여 doxycyclin hyclate(10mg/kg)를 복강내 주사한 뒤 위에서 언급한 모든 parameter를 측정, 비교하였다. 결과 : 장의 재관류로 유도된 급성폐손상에서 doxycyclin은 폐손상을 감소시켰는데 이것은 doxycyclin에 의한 lung MPO, 산소기생성, lung $PLA_2$ 활동도의 감소에 의한 것으로 생각되었다. 결론 : 장의 재관류로 유도된 급성폐손상은 호중구에서 생성되는 산소기, 특히 $PLA_2$의 활성화에 의해 생성된 산소기에 의한 것으로 생각되며 이때 doxycyclin은 $PLA_2$를 억제하여 산화성 스트레스를 감소시킴으로서 폐손상의 감소를 가져오는 것으로 생각된다.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 1996년도 정기총회 및 학술발표회
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• pp.17-17
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• 1996

Annexin I is a member of the annexin family of calcium dependent phospholipid binding proteins and has anti-inflammatory activity by inhibiting phospholipase A$_2$ (PLA$_2$). Recent X-ray crystallographic study of annexin I identified six Ca$\^$2+/ binding sites, which was different types (type II, III) from the well-known EF-hand motif (type I). (omitted)