Arachadonic acid

Muscarinic receptor Brain binding Dopaminergic receptor binding Intracellular Ca concentration, apoptosis Cytosolic phospholipase A2 expression arachadonic acid release... 

During ischaemia, the activity of cellular antioxidant systems may be reduced (Ferrari et al. 1985 GaUnanes etal. 1992). In addition, a number of cellular pathways that produce free radicals are primed during ischaemia such as the xanthine/xanthine oxidase system (McCord, 1987), catecholamine auto-oxidation (Jackson et al., 1986) and the arachadonic acid pathway (Halliwell and Gutteridge, 1989). Thus, during early reperfusion there is a burst of free radical production (see Fig. 4.1) that may overwhelm the antioxidant systems of the cells. 

It is an unfortunate consequence of the use of Christian name abbreviation (A. Spirin), that Alex always evokes for me a well known analgesic, antipyretic and antiinflammatory agent, which John Vane showed in 1971 to be an inhibitor of the synthesis of prostaglandins from arachadonic acid. 

Deoxycholic acid Arachadonic acid rich phospholipids Low density lipoproteins Transferring ... 

Inhibition of cyclooxygenase 1, reducing the breakdown of arachadonic acid to thromboxane A2 and platelet granule release... 

Horse platelets contain a large nonmetabohe pool of serotonin and adenine nucleotides within dense bodies (White et al. 1976). Calcium ionophore (A23187) and high doses of thrmnbin (0.4 unitsAnl), but not collagen, ADP, or arachadonic acid, induced secretion of ATP and/or C-serotonin (Weiss et al. 1990, Boudreaux et al. 1988). 

In general, ruminant platelets are less responsive to agonists compared to platelets of other species (Bondy and Gentry 1989). Bovine platelets are more sensitive to stimulation by PAF than by ADP or thrombin. ADP-induced aggregation does not induce dense granule secretion. Epinephrine, arachadonic acid, and serotonin do not aggregate bovine platelets... 

Cat platelets readily aggregate in response to ADP, collagen, thrombin, serotonin, and arachadonic acid, and frequently exhibit a biphasic response (Meyers 1986). A biphasic response to ADP is consistently seen. Cat platelets generate relatively large amounts of thromboxane Bj when exposed to arachidonic acid and consistently aggregate irreversibly (Meyers et al. 1981). Arachidonic acid-induced aggregation appears to be independent of dense granule secretion. 

A study by W. Breu and M. Hagenlocher, published in the German journal Arzneim-Forsch Drug Research in 1992, used a supercritical carbon dioxide extract of saw palmetto. The researchers were exploring the mechanism of action of this herb for benign prostatic hyperplasia. Most research has studied and confirmed the ability of Serenoa to inhibit 5-alpha-reductase and reduce the formation of DHT. The researchers in this experiment found another mechanism of action for saw palmetto inhibition of the biosynthesis of inflammatory arachadonic acid metabolites, specifically the cyclooxygenase and 5-lipoxgenase pathways. 

Horimoto N, Nabekura J, Ogawa T. Arachadonic acid activation of potassium channels in rat visual cortex neurons. Neuroscience 1997 77 661-671. 

Keros S, McBain CJ. Arachadonic acid inhibits transient potassium currents and broadens action potentials during electrographic seizures in hippocampal pyramidal and inhibitory intemeurons. J Neurosci 1997 17 3476-3487. 

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... 

Some receptors are named after the natural agent, e.g. histamine and 5HT, but others after natural products, the interactions with which were the only means of characterisation before the structures of the true transmitters were known, e.g. opioid after opium (morphine) - the natural ligands here are peptides (enkephalins and endorphins) cannabinoid after cannabis - the natural ligands are amides of arachadonic acid. 

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