Norepinephrine defined

The adrenergic dragp are important in the care and treatment of patients in shock. Shock is defined as a life-threatening condition of inadequate perfusion. In shock, there is an inadequate supply of arterial blood flow and oxygen delivery to the cells and tissues. The body initiates compensatory mechanisms to counteract the symptoms of shock (eg, the release of epinephrine and norepinephrine), hi some situations, the body is able to compensate and blood pressure is maintained. However, if shock is untreated and compensatory mechanisms of the body fail, irreversible shock occurs and... 

Paczkowski FA, Sharpe lA, Dutertre S, Lewis RJ. (2007) X-Conotoxin and tricyclic antidepressant interactions at the norepinephrine iransporter define a new transporter model. J Biol Chem 282 17837-17844. 

Recent investigations into intracellular events have begun to define the postsynaptic events through which TCAs appear to exert their effects (Morinobu et ah, 1995). One of the observations made was down-regulation of transcription factors for early gene products such as c-Fos. C-Fos is normally produced in response to periods of stress. In research with rats, TCAs as well as other antidepressants have been shown to decrease the expression of c-Fos in areas of frontal cortex after chronic but not acute treatment. Other psychotropic medications (e.g., cocaine and haloperidol) with similar acute effects on norepinephrine/serotonin neurotransmission have not shown this same chronic effect. It has been speculated that the decreased production of c-Fos is the end product of a cascade of events stimulated by increased norepinephrine levels (Morinobu et ah, 1995). 

TCAs derive their name from their chemical structure aU tricyclics have a three-ring nucleus. Currently, most clinicians are moving away from using TCAs as first-line drugs relative to the newer antidepressants, they tend to have more side effects, to require gradual titration to achieve an adequate antidepressant dose, and to be lethal in overdose. Some data suggest that TCAs may be more effective than SSRIs in the treatment of major depression with melancholic features (Danish University Antidepressant Group 1990 Perry 1996) however, many skilled clinicians and researchers continue to prefer the newer antidepressants, even for patients with melancholia, for the aforementioned reasons. Newer medications that affect both norepinephrine and serotonin (e.g., venlafaxine and mirtazapine) also may have superior efficacy in severely iU depressed patients or when remission is defined as the outcome (Thase et al. 2001). 

Terms in bold are defined i neuroendocrine system 882 radioimmunoassay (RIA) 884 Scatchard analysis 884 endocrine glands 886 paracrine 886 autocrine 886 insulin 887 epinephrine 888 norepinephrine 888 catecholamines 888 eicosanoid... 

Soon after the demonstration of separate o-and Breceptors, it was found that there were at least two subtypes of Breceptors, designated Bi and 32. Betai and B2 Receptors are operationally defined by their affinities for epinephrine and norepinephrine Bi receptors have approximately equal affinity for epinephrine and norepinephrine, whereas 2 receptors have a higher affinity for epinephrine than for norepinephrine. Subsequently, B3 receptors were identified as a novel and distinct third B adrenoceptor subtype. Some of the properties of each of these receptor types are listed in Table 9-1. 

When narrowly defined, the biogenic amines comprise only epinephrine, norepinephrine, and dopamine. However, in a broader and more practical sense, serotonin, histamine, and acetylcholine are also included. 

The exact mechanism of this peripheral adrenergic neuron blocking agent is not well defined. Reserpine administration results in depleted stores of norepinephrine, dopamine, and serotonin in multiple organs. The decreased peripheral resistance and cardiac output that results is manifested as a decrease in blood pressure. A central nervous system (CNS) effect may also play a role in decreasing blood... 

The very large G protein-coupled receptor family has provided many examples of the definition of residue roles in drug interactions. Thus, for the beta-adrenoceptor, critical interacting residues have been determined to be aspartate-113 on helix III, serine-204 and -207 on helix V and phenylalanine-290 on helix VI. Such studies have defined a homologous binding pocket on this receptor family that is shared by the cationic neurotransmitters, acetylcholine, histamine, norepinephrine etc., and related small ligands. 

The synthesis and demonstration that R(—)N-(2-cholorethyl)-10,ll-dihydroxynor-aporphine (N-chloroethylnorapomorphine, NCA, 4c) may cause persistent DA receptor blockade, suggested that this inhibition of DA receptor function may involve covalent bonding of a receptor binding site (Neumeyer et al. 1981d). NCA blocked DA-sensitive adenylate cyclase activity (D-2) in a non-competitive and apparently irreversible manner. This effect was prevented by coincubation with DA or APO but not with norepinephrine. Analogs of NCA with low affinity for DA receptor sites defined by binding of 1 nM APO (Arana et al. 1981) also had... 

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