| prostacyclin | <biochemistry> Unstable prostaglandin released by mast cells and endothelium, a potent inhibitor of platelet aggregation, also causes vasodilation and increased vascular permeability. Release enhanced by bradykinin. (13 Nov 1997) |
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| prostacyclin isomerase | <enzyme> No information given on mechanism 3/83 Registry number: EC 5.- Synonym: pgi isomerase (26 Jun 1999) |
| prostacyclin synthetase | <enzyme> Converts endoperoxides to prostacyclin Registry number: EC 5.3.99.4 Synonym: prostacyclin synthase, pgi2 synthetase, pgi2 synthase, prostaglandin-i synthase (26 Jun 1999) |
| prostaglandin | <protein> (prostate gland + in because they were originally discovered in semen) any of a group of components derived from unsaturated 20 carbon fatty acids, primarily arachidonic acid, via the cyclooxygenase pathway that are extremely potent mediators of a diverse group of physiologic processes. The abbreviation for prostaglandin is PG, specific compounds are designated by adding one of the letters A through I to indicate the type of substituents found on the hydrocarbon skeleton and a subscript (1, 2 or 3) to indicate the number of double bonds in the hydrocarbon skeleton for example, PGE2. The predominant naturally occurring prostaglandins all have two double bonds and are synthesised from arachidonic acid (5, 8, 11, 14 eicosatetraenoic acid) by the pathway shown in the illustration. The 1 series and 3 series are produced by the same pathway with fatty acids having one fewer double bond (8, 11, 14 eicosatrienoic acid or one more double bond (5, 8, 11, 14, 17 eicosapentaenoic acid) than arachidonic acid. The subscript a or á indicates the configuration at C 9 (a denotes a substituent below the plane of the ring, á, above the plane). The naturally occurring PGF's have the a configuration, for example, PGF2a. All of the prostaglandins act by binding to specific cell surface receptors causing an increase in the level of the intracellular second messenger cyclic AMP (and in some cases cyclic GMP also). The effect produced by the cyclic AMP increase depends on the specific cell type. In some cases there is also a positive feedback effect. Increased cyclic AMP increases prostaglandin synthesis leading to further increases in cyclic AMP. Group of compounds derived from arachidonic acid by the action of cyclooxygenase that produces cyclic endoperoxides (PGG2 and PGH2) that can give rise to prostacyclin or thromboxanes as well as prostaglandins. Were originally purified from prostate (hence the name), but are now known to be ubiquitous in tissues. PGs have a variety of important roles in regulating cellular activities, especially in the inflammatory response where they may act as vasodilators in the vascular system, cause vasoconstriction or vasodilation together with bronchodilation in the lung and act as hyperalgesics. Prostaglandins are rapidly degraded in the lungs and will not therefore persist in the circulation. Prostaglandin E2 PGE2) acts on adenylate cyclase to enhance the production of cyclic AMP. (18 Nov 1997) |
| prostaglandin antagonists | Compounds that inhibit the action of prostaglandins. (12 Dec 1998) |
| prostaglandin d2 | <chemical> 9,15-dihydroxy-11-oxoprosta-5,13-dien-1-oic acid. The principal cyclooxygenase metabolite of arachidonic acid. It is released upon activation of mast cells and is also synthesised by alveolar macrophages. Among its many biological actions, the most important are its bronchoconstrictor, platelet-activating-factor-inhibitory, and cytotoxic effects. Chemical name: Prosta-5,13-dien-1-oic acid, 9,15-dihydroxy-11-oxo-, (5Z,9alpha,13E,15S)- (12 Dec 1998) |
| prostaglandin E1 | <chemical> A potent vasodilator agent that increases peripheral blood flow. It inhibits platelet aggregation and has many other biological effects such as bronchodilation, mediation of inflammation, etc. Pharmacological action: fibrinolytic agent, platelet aggregation inhibitors, vasodilator agents. Chemical name: Prost-13-en-1-oic acid, 11,15-dihydroxy-9-oxo-, (11alpha,13E,15S)- (12 Dec 1998) |
| prostaglandin E1 monooxygenase | <enzyme> Requires NADPH; liver microsome enzyme is cytochrome p-450 dependent; catalyses omega hydroxylation Registry number: EC 1.14.- Synonym: pge1 monooxygenase (26 Jun 1999) |
| prostaglandin E2 | <chemical> 7-(3-hydroxy-2-(3-hydroxy-1-octenyl)-5-oxocyclopentyl)-5-heptenoic acid. The most common and most biologically active of the mammalian prostaglandins. It exhibits most biological activities characteristic of prostaglandins and has been used extensively as an oxytocic agent. The compound also displays a protective effect on the intestinal mucosa. Pharmacological action: oxytocics. Chemical name: Prosta-5,13-dien-1-oic acid, 11,15-dihydroxy-9-oxo-, (5Z,11alpha,13E,15S)- (12 Dec 1998) |
| prostaglandin endoperoxide synthase | <enzyme> An enzyme complex that catalyses the formation of prostaglandins from the appropriate unsaturated fatty acid, molecular oxygen, and a reduced acceptor. See: cyclooxygenase Chemical name: (5Z,8Z,11Z,14Z)-Icosa-5,8,11,14-tetraenoate,hydrogen-donor:oxygen oxidoreductase Registry number: EC 1.14.99.1 (12 Dec 1998) |
| prostaglandin endoperoxide thromboxane isomerase | <enzyme> Converts prostaglandin h2 to thromboxane b2 and 12l-hydroxy-5,8,10-heptadecatrienoic acid Registry number: EC 5.3.99.- Synonym: endoperoxide-tx isomerase, pg endoperoxide thromboxane isomerase (26 Jun 1999) |
| prostaglandin endoperoxides | Precursors in the biosynthesis of prostaglandins and thromboxanes from arachidonic acid. They are physiologically active compounds, having effect on vascular and airway smooth muscles, platelet aggregation, etc. (12 Dec 1998) |
| prostaglandin endoperoxides, synthetic | Synthetic compounds that are analogs of the naturally occurring prostaglandin endoperoxides and that mimic their pharmacologic and physiologic activities. They are usually more stable than the naturally occurring compounds. (12 Dec 1998) |
| prostaglandin F2a | <chemical> 7-(3,5-dihydroxy-2-(3-hydroxy-1-octenyl)cyclopentyl)-5-heptenoic acid. A natural prostaglandin f analog that has oxytocic, luteolytic, and abortifacient activities. Due to its vasocontractile properties, the compound has a variety of other biological actions. Pharmacological action: abortifacient agents, non-steroidal, oxytocics. Chemical name: Prosta-5,13-dien-1-oic acid, 9,11,15-trihydroxy-, (5Z,9alpha,11alpha,13E,15S)- (12 Dec 1998) |
| prostaglandin F2a tromethamine | An oxytocic agent. Synonym: prostaglandin F2a tromethamine. (05 Mar 2000) |