Histamine and

B. UvnAS, ed.. Histamine and Histamine Antagonists, Springer-Vedag, Berlin, 1991. 

Melatonin [73-31-4] C 2H N202 (31) has marked effects on circadian rhythm (11). Novel ligands for melatonin receptors such as (32) (12), C2yH2gN202, have affinities in the range of 10 Af, and have potential use as therapeutic agents in the treatment of the sleep disorders associated with jet lag. Such agents may also be usehil in the treatment of seasonal affective disorder (SAD), the depression associated with the winter months. Histamine (see Histamine and histamine antagonists), adenosine (see Nucleic acids), and neuropeptides such as corticotropin-like intermediate lobe peptide (CLIP) and vasoactive intestinal polypeptide (VIP) have also been reported to have sedative—hypnotic activities (7). 

Histamine AND histamine antagonists). It is formed from histidine by the enzyme L-histidine decarboxylase. In the periphery, histamine is stored ia mast cells, basophils, cells of the gastric mucosa, and epidermal cells. In the CNS, histamine is released from nerve cells and acts as a neurotransmitter. The actions of histamine ate terrninated by methylation and subsequent oxidation via the enzymes histamine-/V-methyltransferase and monoamine oxidase. 

Activation of histamine receptors with histamine and selective agonists such as dimaprit (205) and impromidine (206) results ia gastric acid... 

The process of reabsorption depends on the HpophiHc—hydrophiHc balance of the molecule. Charged and ioni2ed molecules are reabsorbed slowly or not at all. Reabsorption of acidic and basic metaboHtes is pH-dependent, an important property in detoxification processes in dmg poisoning. Both passive and active carrier-mediated mechanisms contribute to tubular dmg reabsorption. The process of active tubular secretion handles a number of organic anions and cations, including uric acid, histamine, and choline. Dmg metaboHtes such as glucuronides and organic acids such as penicillin are handled by this process. 

Tricyclic Antidepressants. Imipramine [50-49-7] (32), which was the first tricycHc antidepressant to be developed, is one of many useful psychoactive compounds derived from systematic molecular modifications of the antihistamine prometha2ine [60-87-7] (see Histamine and histamine antagonists). The sulfur atom of prometha2ine was replaced with an ethylene bridge and the dimethylamino group attached to an / -propyl group, rather than to an isopropyl one, of the side chain. The actual synthesis of (32) is typical of the compounds in this class (37). 

FIGURE 4.5 The structures of some ammo acids that are not normally found in proteins but that perform other important biological functions. Epinephrine, histamine, and serotonin, although not amino acids, are derived from and closely related to amino acids. 

In this histamine H2-receptor model, both histamine and its antagonists bind to [18]aneN6 3 H + forming 1 1 complexes at neutral pH, and the histamine antagonists are more strongly bound to the receptor model (see Fig. 9). Although this picture... 

Data points are subjected to nonlinear curve fitting. For these data, Equation 12.5 is used to fit the curve with basal = 0. The fitting parameters for histamine and E-2-P are given in Table 12.4b. The curves are shown in Figure 12.5a. 

Equiactive concentrations of histamine and E-2P are calculated (see method in Section 12.2.1). For this calculation, responses produced by E-2-P are used since they covered a convenient range to characterize both dose-response curves. The equiactive concentrations are shown in Table 12.4c. 

Allergy. Figure 2 Histamine H-1 receptor antagonists inhibit response of target cells to histamine and relieve hay fever-like symptoms. 

Heart Histamine (and also other mediators) induce arrhythmias which can be fatal. 

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