METABOLISM AND INACTIVATION

METABOLISM AND INACTIVATION Catecholamins are metabolized and inactivated in one of three anatomic structures: 1 - in a neurone cosecreting these bonds after they will get back to a cytoplasma during the process known under the name of return capture; 2 - in cells (targets) after rendering of the biological action and 3 - in a liver after excision from blood. The first process proceeds mainly in neurones of a brain buy cipro antibiotic and in peripheric nervous system. This return capture serves as the fast and economic mechanism; cancellation of the catecholamins acting in a role local . The Most part of amine absorbed thus gets again into secretory granules and is repeatedly used by a neurone in a cycle of secretory processes. The part, the amine, not getting to granules, is blasted in a neurone cytoplasma. It is necessary to notice, that process of capture by transport through a membrane of a neurone and a chromaffin granule differs from amine accumulation in granules. The substances interfering one process, can practically not influence another;. So, Reserpinum interfering accumulation of Noradrenalinum, influences capture only in the minimum degree, and cocaine and antidepressants (Imipraminum, Imizinum), blocking capture, do not render visible influence on accumulation. For the catecholamins allocated in a blood flow with a cerebral layer of adrenals, 2nd and 3rd ways of a metabolism serve mainly.
The metabolism of catecholamins is defined by action of two enzymes - monoaminoxidases and a catechol-about-methyltransferase. These enzymes are present at a liver, kidneys, a blood plasma and a cytoplasma of neurones. The main metabolites of Noradrenalinum and adrenaline are acid and metoksi-oksifenilglikol, both excreted with urine. Products of a biological metabolism of Dofaminum, found out in urine, are acid and . Though additional minor O-metilirovannye adrenaline and Noradrenalinum metabolites - and , formed under action a catechol-about-methyltransferase, make only small fraction of urinary metabolites, they reflect quantity of biologically active amines allocated in blood, than products better and more immediately. The catecholamins absorbed by cells, such as neurones and hepatocytes, are metabolized almost completely. At urine there is only very much a small amount of not changed amines. STEROID buy cheap rimonabant HORMONES OF ADRENALS The cortex of adrenals is the main source glucocorticoid and of steroid hormones and to a lesser degree sexual steroid hormones. The cortical substance is parted on three zones which can be distinguished by a morphological kind of cells and steroid bonds produced by them. The most external layer of a cortex - a glomerular zone - is a place of synthesis of mineralocorticoids from which at the person and a rat Aldosteronum and Corticosteronum have the greatest functional value accordingly. Cells of an average zone - fascicular - produce glucocorticoids a hydrocortisone and Cortisonum. The inside layer - a mesh zone - also takes part in synthesis of glucocorticoids and, besides, as consider, makes a small amount of steroid sexual hormones of androgens and estrogens. As the main sources of steroid sexual hormones sexual glands, however, serve, and to production of sexual hormones a cortex of adrenals attach functional significance only in unusual conditions when on ways of biosynthesis to epinephral glands there are defects of enzymes. The functional sectioning of biosynthetic activity of a cortex of adrenals on anatomic areas is based on results of histological and histochemical researches of this tissue after "excision" of its specific stimulators. The hypophysectomy and absence caused by it lead to an atrophy of fascicular and mesh zones whereas in a glomerular zone there are very much little changes. At the same time the chronic load sodium causes a selective atrophy of a glomerular zone. On the contrary, at long stimulation or restriction of consumption of sodium there is accordingly a hypertrophy of a fascicular and mesh or glomerular zone. As it will be shown further, some specific enzymes necessary for formation a mineral - and glucocorticoids, are found out only in specific zones of a cortical layer of adrenals. BIOSYNTHESIS STAGES Biosynthesis of steroid hormones passes difficult sequence of stages supervised by enzymes ( 3-17 [37, 38]. The nearest chemical precursor of adrenal steroids is cholesterol which not only is absorbed by cells of a cortex of adrenals from blood, but also is formed in these cells. Cholesterol synthesis begins about Acetyl-soa and passes through a number of intermediate products. The exact parity absorbed of blood and the cholesterol formed in cells is not known, but, apparently, both processes play an essential role in maintenance of biosynthesis of steroid hormones with necessary substrate.