Blood platelets metabolism

Ca + mobilization by metabolites of arachadonic acid. One possible mechanism by which this amplification process could proceed is through Ca + activation of enzymes involved in arachadonic acid (AA) metabolism. In this regard, it is known that blood platelets metabolize endogenous AA to the potent... 

Serotonin is stored in synaptic vesicles and blood platelets in the form of an ATP complex in the ratio of 2 1. Very little is known about its release, but exocytosis is the assumed mechanism. The released neurotransmitter is deactivated primarily by reuptake, but a significant amount is metabolized by MAO to the corresponding indoleacetic acid. 

Srivastava, . C. and N. Malhotra. 1991. Acetyl eugenol, a component of oil of cloves (Syzygium aromaticum L.) inhibits aggregation and alters arachidonic acid metabolism in human blood platelets. Prostaglandins Leukot. Essent. Fatty Acid 42 73-81. 

Skin sweat, piio motor Male ejaculation Blood platelet aggregation Metabolic effect hyperkalaemla 1 Metabolic effects hypokalaemia (p ) hepatic glycogenolysis (p ) lipolysis (P. P )... 

Srivastava KC, Tyagi OD. Effects of a garlic-derived principle (ajoene) on aggregation and arachidonic acid metabolism in human blood platelets. Prostagland Leukotr Essent Fatty Acids 1993 49 587-595. 

Tryptophan appears to be converted to a larger number of metabolites than any of the other amino acids. The degradation of tryptophan in animals occurs mainly in two pathways, I and II (Figure 4.1). The first major pathway (I), initiated by the action of tryptophan dioxygenase, involves oxidation of tryptophan to N - fc > r my I ky n urenine and the formation of a series of intermediates and byproducts, most of which appear in varying amounts in the urine, the sum of which accounts for the total metabolism of tryptophan, approximately. The second pathway (II) involves hydroxylation of tryptophan to 5-hydroxytryptophan and decarboxylation of this compound to 5-hydroxytryptamine (serotonin), a potent vasoconstrictor found particularly in the brain, intestinal tissues, blood platelets, and mast cells. A small percentage (3%) of dietary tryptophan is metabolized via the pathway (III) to indoleacetic acid. Other minor pathways also exist in animal tissues. 

BIOLOGICAL ACTIONS Gastrointestinal smooth muscle Reproductive smooth muscle Respiratory smooth muscle Cardiovascular system Blood platelet aggregation Metabolic effects... 

Srivastava, K.C., A. Bordia, and S.K. Verma. 1995. Curcumin, a major component of food spice turmeric (Curcuma longa), inhibits aggregation and alters eicosanoid metabolism in human blood platelets. Prostaglandins Leukotrienes Essent. Fatty Acids 52(4) 223-227. 

Loesche, W., W.A. Groenewegen, S. Krause, P. Spangenberg, and S. Heptinstall. 1988. Effects of an extract of feverfew (Tanacetum parthenium) on arachidonic acid metabolism in human blood platelets. Biomed. Biochim. Acta 47(10-11) S241-S243. 

In blood platelets approximately 60% of the ADP + ATP is contained in granules together with serotonin (5-hydroxytryptamine). These adenine nucleotides are relatively inert metabolically, as incubation of platelets with radioactive precursors does not lead to their labeling, whereas non-particulate nucleotides readily become highly labeled (see references 28, 29). 

Thrombosis is an often encountered consequence of atherosclerotic alterations of the vessel wall, and there can be no doubt that in its genesis, blood platelets play a predominant role (cf.55)< Platelets in turn are of considerable interest as the model of a metabolically active, contractile cell, capable of reacting to a variety of external stimuli. In the course of their activation, they display a series of morphological and biochemical alterations, in the course of which they aggregate and acquire procoagulant properties. It is of particular interest that lipids and fatty acids are known to interact with platelets and with the blood clotting system, and this again justifies the inclusion of a chapter on thrombosis in this series of articles on diet and atherosclerosis. ... 

Metabolism of linoleic and arachidonic acids in human blood platelets. 

Coffee is one of the most consumed beverages and caffeine is used commonly as a drug in human medicine. In a calorimetric study the influence of caffeine on cell metabolism was tested [20]. Heat production rate was measured in platelets from healthy subjects after administration of 100 or 200 mg of caffeine, corresponding to 1 or 2 cups of coffee. Increased values were recorded and return to normal levels was noted 1 h later. It is presumed that the effect of caffeine on platelet metabolism is due to increased concentrations of catecholamines. It is in fact known from previous investigations that caffeine stimulates production of adrenaline and noradrenaline. Another effect of caffeine observed in the calorimetric study was a temporary, but significant, increase of blood pressure. It is possible that the described effect on cell metabolism is not limited to platelets, as indicated by previous studies showing increased basal metabolism after administration of caffeine. It cannot... 

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