Some receptor places

Some receptor places, for example for Acetylcholinum and catecholamins, are characterised by means of labelled antagonists. Rather low affinity receptors to cholinergic or low concentration specific b-adrenergic places on cells-targets is framed by difficulties for the characteristic of these receptors by researches with application order cheap ultram of labelled agonists. The opinion on a cellular membrane as about a scene of action hormones was generated on the basis of observations Sutherland according to which interaction of catecholamins with a plasmatic membrane of erythrocytes of a pigeon leads to activation of adenylatecyclase [4]. After that it has been shown, that many hormones contact receptors of a plasmatic membrane and influence the activity localised in it, such, as adenylatecyclase or mechanisms of ionic transport ( 4-2). That fact testifies To superficial localisation of receptors hormones also, that short-term influence of a hormone causes long reaction of cells-targets which it is possible to charge to the bound hormone, and also ability of specific antiserums quickly to terminate hormones in vitro. It is known also, that enzymes or other agents influencing membranous fibers and lipids, modify or liquidate ability hormones to stimulate adenylatecyclase.
The most weighty proofs of localisation of receptors hormones on a plasmatic membrane have been received in researches and direct experiences on linkage of labelled biologically active hormones with preparations of membranes or intact cells. These approaches have allowed to find out precisely localisation and parametres of linkage of cellular receptor sites, and also their functional communication with cell-target reactions. Ability hormones to co-operate with cells-targets (or on the contrary) should depend on presence of specific binding sites on a plasmatic membrane (receptors) which take molecules carrying the information from an extracellular liquid. So, "awareness" of cells of a fascicular zone of a cortex of adrenals in the relation regulating influences is defined by concentration and a profile of secretion , arriving to epinephral glands. Extremely low concentration (nearby 10~10 M) in blood at excess of other fibers demand hormones, that receptors of cells-targets possessed as high specificity (allowing to learn a hormone), and high affinity to a hormone (allowing to bind it at low concentration). Well studied class of receptors for "traditional" hormones (such as peptides of a pituitary body and hormones of a gastroenteric tract) has replenished with similar sites for local and molecules (such as Acetylcholinum, catecholamins and Prostaglandinums), and later and for the group consisting approximately from 20 neuropeptids (as before known, and recently found out) which regulate, apparently, function of peripheric and central nervous system. This huge number hormones is characterised by a high charge and a relative hydrophylic nature, absence of appreciable linkage with fibers of plasma and ability to be bound to specific distinguishing sites on open area of receptor molecules. The cells-targets vpxl for you built in a plasmatic membrane. Consider, that other specialised area internal, with a membrane, parts of receptors hormones co-operates with an intramembranous part molecules or enzymes, such as adenylatecyclase, whose catalytic domain is accessible with internal, cytoplasmatic, surfaces of a cellular membrane. Though now it is known, that many hormones after linkage with superficial receptors nevertheless get into a cell, initial interaction with an external surface of a plasmatic membrane is a necessary condition of stimulation of reactions of cells-targets as intracellular introduction hormones does not cause characteristic reactions of such cells. Behind linkage of a hormone with a superficial receptor there comes activation of one or more membranous the systems, defining changes in mechanisms of transport and distribution of ions, and also activation of cytoplasmatic processes which regulate cell-target function. Many of these stages of activation include, apparently, membranous or cytoplasmatic fibers that leads to change of the enzymatic functions responsible for transport a metabolism of molecules, playing the important role in cellular activity. The main membranous enzyme regulated by hormones, adenylatecyclase, formation , necessary for processes , arising is at cell-target stimulation. To other membranous enzymes which activity is influenced by a hormone-receptor interaction, the enzymes participating in a circuit , the methyltransferases which are taking part in a methylation , and also , responsible for membranous concern. Last process is a source of formation of precursors (such, as arachidonic acid) of Prostaglandinums, , and other active metabolites. Hormonal influences on Na +, To +-dependent , the protein kinase bound to a membrane and a catechol-about-methyltransferase were observed also. Thus, at level of a plasmatic membrane hormones induce set of the processes participating in integrated reactions of cells-targets on activation of receptors homologous .