Heparin mast cell produced

Although the most common and characteristic type of connective tissue cell is the fibroblast many other types of cell are present in loose connective tissue. These mostly have a protective role. They include fat cells, macrophages, plasma cells, mast cells and leucocytes. The macrophages and some of the leucocytes are phagocytic and are able to engulf cellular debris, bacteria and inert foreign matter the plasma cells are derived from B-lymphocytes and produce immunoglobuUns while the mast cells produce heparin and histamine and also, in some species, serotonin (5-hydroxytryptamine). 

Heparin is biosynthesized in mast cells as a PG with approximately 10 GAG side chains (5). When mast cells degranulate, PG heparin is enzymatically degraded to GAG heparin (Fig. 1). Exogenous heparin is used primarily as an anticoagulant/antithrombotic agent. Heparin is produced from mast-cell-rich tissues, such as lung and intestinal mucosa, in metric ton quantities yearly for use as a pharmaceutical agent. 

Heparin (heparin sodium) is a mixture of highly electronegative acidic mucopolysaccharides that contain numerous N- and O-sulfate linkages. It is produced by and can be released from mast cells and is abundant in liver, lungs, and intestines. 

Heparin, but not heparan sulfate, is a good anticoagulant, probably because of higher charge density. Heparan sulfate is found in virtually all tissues, but heparin appears to be produced only by mast cells. Their different distributions may reflect differences in activity of the deacetylase. 

Heparin is synthesized in connective-tissue type mast cells, as part of the serglycin proteoglycan. HS is produced by most mammalian (and many other) cells and is bound to a variety of core proteins, in particular syndecans, gly-picans, perlecan, and agrin. Following translation in the rough endoplasmic... 

GAGs are classified into several major types based on the nature of the repeating disaccharide unit heparan sulfate, chondroitin sulfate, dermatan sulfate, keratan sulfate, and hyaluronan. A hypersulfated form of heparan sulfate called heparin, produced mostly by mast cells, plays a key role In allergic reactions. It is also used medically as an anticlotting drug because of its ability to activate a natural clotting inhibitor called antlthrombln III. 

Snellman, Sylven and Julen isolated the heparin polypeptide and showed that this material is a potent antithrombin on thrombin with purified fibrinogen, suggesting that heparin in the mast cells is in the active anticoagulant form. Electrophoresis shows that this native heparin forms a complex compound with thrombin and also with a lipoprotein molecule. They conclude the whole heparin complex is produced in the intergranular cytoplasm of the tissue mast cells. 

Heparin is predominandy produced by mast cells as part of a proteoglycan (PG), where the GAG chains are covalently attached (O-linked) to a serglycin core protein. After synthesis, the heparin chains are cleaved, and the so obtained disperse mixture of polysaccharides is stored in the cytoplasmic granules of the cells. HS—as well as CS and DS—is also found as O-glycosidic part of PGs, but they can be attached to a variety of different core proteins (e.g., syndecans and glypicans). Almost all mammahan cells biosynthesize such PGs, which can be found as part of cell membranes or as components of the extracellular matrix (Rabenstein, 2002 Silbert Sugumaran, 2002). 

A model [22] of how heparin acts specifically in many biological systems in modifying activities of complex ions may be provided by the metachromatic effect on dyes referred to earlier. The dye. Azure A, shows maximum light absorption at 610 nm. This is decreased when heparin is added, and a new absorption band at 505 mu develops. Heparins and heparinoids are able to produce this color change at very low concentrations and under conditions unfavorable to other metachromatic inducing substances. However, little attention has been paid to the numerous experimental observations reported on metachromasia with heparin and heparinoids, of practical importance to those using this color reaction in studies on heparin and mast cells. In... 

The mastocytes (mast cells) are highly differentiated elements of the reticular connective tissue which are able to produce and store histamine, heparin, and perhaps also hyaluronic acid. 

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