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Hormones thromboxanes

Animal cells can modify arachidonic acid and other polyunsaturated fatty acids, in processes often involving cyclization and oxygenation, to produce so-called local hormones that (1) exert their effects at very low concentrations and (2) usually act near their sites of synthesis. These substances include the prostaglandins (PG) (Figure 25.27) as well as thromboxanes (Tx), leukotrienes, and other hydroxyeicosanoic acids. Thromboxanes, discovered in blood platelets (thrombocytes), are cyclic ethers (TxBg is actually a hemiacetal see Figure 25.27) with a hydroxyl group at C-15. [Pg.829]

Most GPCRs interact with and activate more than one G-protein subfamily, e.g., with Gs plus Gq/n (histamine H2, parathyroid hormone and calcitonin recqrtors), Gs plus G (luteinising hormone receptor, 32-adrenoceptor) or Gq/11 plus G12/13 (thromboxane A2, angiotensin ATb endothelin ETA receptors). Some receptors show even broader G-protein coupling, e.g., to Gi, Gq/n plus Gi n ( protease-activated receptors, lysophosphatidate and sphingosine-1-phosphate receptors) or even to all four G-protein subfamilies (thyrotropin receptor). This multiple coupling results in multiple signaling via different pathways and in a concerted reaction of the cell to the stimulus. [Pg.1238]

Amino acid receptors Monoamine receptors Lipid receptors Purine receptors Neuropeptide receptors Peptide hormone receptors Chemokine receptors Glycoprotein receptors Protease receptors Metabotropic glutamate and GABAb receptors Adrenoceptors, dopamine and 5-HT receptors, muscarinic and histamine receptors Prostaglandin, thromboxane and PAF receptors Adenosine and ATP (P2Y) receptors Neuropeptide Y, opiate, cholecystokinin VIP, etc. Angiotensin, bradykinin, glucagon, calcitonin, parathyroid, etc. Interleukin-8 TSH, LH/FSH, chorionic gonadotropin, etc. Thrombin... [Pg.69]

The fats also have a plastic function as they are included in cell membranes and other cell structures. The central and peripheral nervous systems are rich in lipids. PNFA are included in cell membranes, with their most significant function being the synthesis of cell hormones — prostaglandins. The properties of cell membranes as well as their interaction with external factors depend on the relation of PNFA concentration in cell components. In humans, prostaglandins are created not only in tissues but also in thrombocytes (thromboxanes) and in leucocytes (leukotrienes). The biological action of thrombocytes is extremely variant and depends on PNFA type which are the basis for fatty acid creation. [Pg.408]

Prostanoids, which consist of prostaglandins (PCs) and thromboxanes (TXs), are biologically synthesized in the body from arachidonic acid by cyclooxygenase, PG hydroperoxydase, and a family of prostaglandin synthases (Fig. 1). They exert a variety of actions as hormones produced locally in various tissues and cells to maintain homeostasis. [Pg.624]

T FIGURE 10-18 Arachidonic acid and some eicosanoid derivatives. (a) In response to hormonal signals, phospholipase A2 cleaves arachidonic acid-containing membrane phospholipids to release arachidonic acid (arachidonate at pH 7), the precursor to various eicosanoids. (b) These compounds include prostaglandins such as PCE, in which C-8 and C-12 of arachidonate are joined to form the characteristic five-membered ring. In thromboxane A2/ the C-8 and... [Pg.358]

Prostaglandins, thromboxanes, and leukotrienes (the eicosanoids), derived from arachidonate, are extremely potent hormones. [Pg.363]

Eicosanoids The eicosanoid hormones (prostaglandins, thromboxanes, and leukotrienes) are derived from the 20-carbon polyunsaturated fatty acid arachidonate. [Pg.888]

Unlike the hormones described above, they are not synthesized in advance and stored they are produced, when needed, from arachidonate enzymatically released from membrane phospholipids by phospholipase A2 (see Fig. 10-18). The enzymes of the pathway leading to prostaglandins and thromboxanes (see Fig. 21-15) are very widely distributed in mammalian tissues most cells... [Pg.888]

Oliveira RLS, Aldrighi JM, Gebara OE, Rocha TRF, D Amico E, Rosano GMC, Ramires JAF. Postmenopausal hormone replacement therapy increases plasmatic thromboxane beta2. Int J Cardiol. 2005 99 449-54. [Pg.271]

Prostaglandins Prostaglandins and the other eicosanoids (prostacyclins, thromboxanes and leukotrienes) are derived from arachidonate. These compounds all act as local hormones. Aspirin reduces inflammation by inhibiting prostaglandin synthase, the enzyme that catalyzes the first step in prostaglandin synthesis. [Pg.311]

Prostaglandins Prostaglandins, and the structurally related molecules prostacyclins, thromboxanes and leukotrienes, are called eicosanoids because they contain 20 carbon atoms (Greek eikosi = 20). These hormones are relatively short-lived and hence act locally near to their site of synthesis in the body. They are derived from the common precursor arachidonate (Fig. 2). This polyunsaturated fatty... [Pg.313]

The benzodioxole ring system is distributed widely in nature and is found in numerous natural products such as safrole and piperonal, as well as a multitude of alkaloids. 1,2-Dioxolanes are intermediates in the arachidonic acid cascade, which is the biochemical pathway from essential fatty acids to prostaglandins and similar hormones. The endoperoxide PGH2 (121) is believed to be formed on initial oxidation of arachidonic acid (120). PGH2 has a half-life of 4-5 minutes and is transformed enzymatically into prostaglandins, prostacyclin and the thromboxanes. These compounds are mediators for the control of platelet aggregation, blood vessel dilation and smooth muscle contraction. [Pg.781]


See other pages where Hormones thromboxanes is mentioned: [Pg.1001]    [Pg.112]    [Pg.190]    [Pg.192]    [Pg.83]    [Pg.127]    [Pg.17]    [Pg.580]    [Pg.198]    [Pg.330]    [Pg.248]    [Pg.244]    [Pg.248]    [Pg.392]    [Pg.623]    [Pg.820]    [Pg.520]    [Pg.9]    [Pg.800]    [Pg.211]    [Pg.214]    [Pg.1210]    [Pg.4]    [Pg.452]    [Pg.204]    [Pg.200]    [Pg.352]    [Pg.377]    [Pg.200]    [Pg.15]    [Pg.72]    [Pg.190]    [Pg.165]   
See also in sourсe #XX -- [ Pg.644 , Pg.645 , Pg.646 ]




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