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  • 1
    ISSN: 1432-1912
    Keywords: Thromboxane A2 (TXA2) ; Prostacyclin (PGI2) ; Human platelets ; Bovine coronary artery ; Non-steroidal antiinflammatory drugs ; Prostaglandin-cyclooxygenase ; Bioassay ; RCS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The action of the non-steroidal antiinflammatory drugs indomethacin, tiaprofenic acid, diclofenac and meclofenamate on vascular and plateletcyclooxygenases was studied by measuring the arachidonic acid-induced thromboxane A2 (TXA2)-formation of washed human platelets and prostacyclin (PGI2)-formation of bovine coronary artery rings. TXA2 was bioassayed as RCS on rabbit aorta strips, PGI2 in terms of its antiaggregatory activity on ADP-induced aggregation of human platelet-rich plasma. All of the substances studied produced concentration-dependent inhibition of PGI2- and RCS-release. The IC50 [μM] in inhibition of RCS-formation was 0.019 for indomethacin, 0.070 for tiaprofenic acid but 44.9 for meclofenamate and 63.2 for diclofenac. The IC50 [μM] in inhibition of PGI2-release was 0.42 for diclofenac, 0.63 for indomethacin and 0.99 for tiaprofenic acid. The data suggest (1) high sensitivity of human platelet-cyclooxygenase against indomethacin and tiaprofenic acid, (2) different sequence of the substances studied in inhibiting arachidonic acid-induced TXA2- and PGI2-formation. The possible therapeutic value of selective inhibition of platelets and vascular cyclooxygenases in discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Basic research in cardiology 76 (1981), S. 239-249 
    ISSN: 1435-1803
    Keywords: heart ; myocardial ischemia ; prostacyclin (PGI2) ; thromboxanes ; coronary vessels ; cyclic AMP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Prostaglandine können als eine Gruppe chemischer Substanzen angesehen werden, die lokal entstehen und die koronare Perfusion an die Stoffwechselerfordernisse des Herzens anpassen. Vorliegende Arbeit gibt eine Zusammenfassung des heutigen Wissensstandes auf diesem Gebiet unter besonderer Berücksichtigung von Prostacyclin (PGI2). Neben Biosynthese und Metabolismus sowie ihrer Beeinflussung durch Pharmaka werden kardiale und koronare Wirkungen von PGI2 beschrieben und mögliche Wirkungsmechanismen der Substanz unter physiologischen und pathophysiologischen (myokardiale Ischämie) Bedingungen diskutiert. Im Mittelpunkt stehen Wechselwirkungen zwischen PGI2, Adenosin und Katecholaminen und ihre möglichen Konsequenzen für die Regulation des koronaren Tonus. Hierzu wird ein Modell vorgestellt, bei dem die direkt-vasokonstriktorischen und stoffwechselsteigernden Katecholaminwirkungen durch Bildung von PGI2 im Gefäßbereich und Adenosin im Herzmuskelstoffwechsel funktionell antagonisiert werden.
    Notes: Summary Prostaglandins may represent one group of local chemical factors that control coronary perfusion and adapt it to the metabolic demands of the heart. Present study summarizes the current knowledge in this field with particular reference to prostacyclin (PGI2). The major biosynthetic pathways and their modification by drugs are briefly outlined. The sources and fates of cardiac prostaglandins are described and possible mechanisms of action discussed in both physiological and pathophysiological (myocardial ischemia) situations. Attention is focussed on the interplay between catecholamines, adenosine and PGI2. A model is presented, based on the hypothesis that adenosine from myocardial metabolism and PGI2 from vascular sites are acting in concert to antagonize sympathetic metabolic and vasoconstrictory influences and to maintain an adequate blood supply to the heart.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1435-1803
    Keywords: prostacyclin ; thromboxane ; platelets ; coronary vessels ; arachidonic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A new experimentalin-vitro model is described, which was used for studying prostacyclin (PGI2)-thromboxane A2 (TXA2)-interactions. Langendorff hearts of guinea pigs are perfused at constant volume with Krebs-Henseleit buffer and washed human platelets (4x108/min). PGI2 and TXA2 release are measured by bioassay. The cardiac and coronary function and the myocardial oxygen consumption are continuously monitored. The platelet count in the cardiac effluent can be measured and the cAMP content has been estimated. This model might be a useful tool for studying the roles of PGI2 and TXA2 in platelet activation and coronary perfusion in terms of endogenously synthesized substances.
    Type of Medium: Electronic Resource
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