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Histamine Release: The secretion of histamine from mast cell and basophil granules by exocytosis. This can be initiated by a number of factors, all of which involve binding of IgE, cross-linked by antigen, to the mast cell or basophil's Fc receptors. Once released, histamine binds to a number of different target cell receptors and exerts a wide variety of effects.Histamine: An amine derived by enzymatic decarboxylation of HISTIDINE. It is a powerful stimulant of gastric secretion, a constrictor of bronchial smooth muscle, a vasodilator, and also a centrally acting neurotransmitter.Histamine Antagonists: Drugs that bind to but do not activate histamine receptors, thereby blocking the actions of histamine or histamine agonists. Classical antihistaminics block the histamine H1 receptors only.Basophils: Granular leukocytes characterized by a relatively pale-staining, lobate nucleus and cytoplasm containing coarse dark-staining granules of variable size and stainable by basic dyes.Receptors, Histamine H1: A class of histamine receptors discriminated by their pharmacology and mode of action. Most histamine H1 receptors operate through the inositol phosphate/diacylglycerol second messenger system. Among the many responses mediated by these receptors are smooth muscle contraction, increased vascular permeability, hormone release, and cerebral glyconeogenesis. (From Biochem Soc Trans 1992 Feb;20(1):122-5)Receptors, Histamine H2: A class of histamine receptors discriminated by their pharmacology and mode of action. Histamine H2 receptors act via G-proteins to stimulate ADENYLYL CYCLASES. Among the many responses mediated by these receptors are gastric acid secretion, smooth muscle relaxation, inotropic and chronotropic effects on heart muscle, and inhibition of lymphocyte function. (From Biochem Soc Trans 1992 Feb;20(1):122-5)p-Methoxy-N-methylphenethylamine: A potent mast cell degranulator. It is involved in histamine release.Receptors, Histamine: Cell-surface proteins that bind histamine and trigger intracellular changes influencing the behavior of cells. Histamine receptors are widespread in the central nervous system and in peripheral tissues. Three types have been recognized and designated H1, H2, and H3. They differ in pharmacology, distribution, and mode of action.Mast Cells: Granulated cells that are found in almost all tissues, most abundantly in the skin and the gastrointestinal tract. Like the BASOPHILS, mast cells contain large amounts of HISTAMINE and HEPARIN. Unlike basophils, mast cells normally remain in the tissues and do not circulate in the blood. Mast cells, derived from the bone marrow stem cells, are regulated by the STEM CELL FACTOR.Histamine H1 Antagonists: Drugs that selectively bind to but do not activate histamine H1 receptors, thereby blocking the actions of endogenous histamine. Included here are the classical antihistaminics that antagonize or prevent the action of histamine mainly in immediate hypersensitivity. They act in the bronchi, capillaries, and some other smooth muscles, and are used to prevent or allay motion sickness, seasonal rhinitis, and allergic dermatitis and to induce somnolence. The effects of blocking central nervous system H1 receptors are not as well understood.Histamine Agonists: Drugs that bind to and activate histamine receptors. Although they have been suggested for a variety of clinical applications histamine agonists have so far been more widely used in research than therapeutically.Receptors, Histamine H3: A class of histamine receptors discriminated by their pharmacology and mode of action. Histamine H3 receptors were first recognized as inhibitory autoreceptors on histamine-containing nerve terminals and have since been shown to regulate the release of several neurotransmitters in the central and peripheral nervous systems. (From Biochem Soc Trans 1992 Feb;20(1):122-5)Immunoglobulin E: An immunoglobulin associated with MAST CELLS. Overexpression has been associated with allergic hypersensitivity (HYPERSENSITIVITY, IMMEDIATE).Histamine H2 Antagonists: Drugs that selectively bind to but do not activate histamine H2 receptors, thereby blocking the actions of histamine. Their clinically most important action is the inhibition of acid secretion in the treatment of gastrointestinal ulcers. Smooth muscle may also be affected. Some drugs in this class have strong effects in the central nervous system, but these actions are not well understood.Anaphylaxis: An acute hypersensitivity reaction due to exposure to a previously encountered ANTIGEN. The reaction may include rapidly progressing URTICARIA, respiratory distress, vascular collapse, systemic SHOCK, and death.Pyrilamine: A histamine H1 antagonist. It has mild hypnotic properties and some local anesthetic action and is used for allergies (including skin eruptions) both parenterally and locally. It is a common ingredient of cold remedies.Cromolyn Sodium: A chromone complex that acts by inhibiting the release of chemical mediators from sensitized mast cells. It is used in the prophylactic treatment of both allergic and exercise-induced asthma, but does not affect an established asthmatic attack.Histamine N-Methyltransferase: An enzyme that catalyzes the transfer of a methyl group from S-adenosylmethionine to histamine, forming N-methylhistamine, the major metabolite of histamine in man. EC 2.1.1.8.Dimaprit: A histamine H2 receptor agonist that is often used to study the activity of histamine and its receptors.Methylhistamines: Histamine substituted in any position with one or more methyl groups. Many of these are agonists for the H1, H2, or both histamine receptors.Anti-Allergic Agents: Agents that are used to treat allergic reactions. Most of these drugs act by preventing the release of inflammatory mediators or inhibiting the actions of released mediators on their target cells. (From AMA Drug Evaluations Annual, 1994, p475)Histidine Decarboxylase: An enzyme that catalyzes the decarboxylation of histidine to histamine and carbon dioxide. It requires pyridoxal phosphate in animal tissues, but not in microorganisms. EC 4.1.1.22.Passive Cutaneous Anaphylaxis: An evanescent cutaneous reaction occurring when antibody is injected into a local area on the skin and antigen is subsequently injected intravenously along with a dye. The dye makes the rapidly occurring capillary dilatation and increased vascular permeability readily visible by leakage into the reaction site. PCA is a sensitive reaction for detecting very small quantities of antibodies and is also a method for studying the mechanisms of immediate hypersensitivity.Histamine H3 Antagonists: Drugs that selectively bind to but do not activate HISTAMINE H3 RECEPTORS. They have been used to correct SLEEP WAKE DISORDERS and MEMORY DISORDERS.Peritoneal Cavity: The space enclosed by the peritoneum. It is divided into two portions, the greater sac and the lesser sac or omental bursa, which lies behind the STOMACH. The two sacs are connected by the foramen of Winslow, or epiploic foramen.Chlorpheniramine: A histamine H1 antagonist used in allergic reactions, hay fever, rhinitis, urticaria, and asthma. It has also been used in veterinary applications. One of the most widely used of the classical antihistaminics, it generally causes less drowsiness and sedation than PROMETHAZINE.Cimetidine: A histamine congener, it competitively inhibits HISTAMINE binding to HISTAMINE H2 RECEPTORS. Cimetidine has a range of pharmacological actions. It inhibits GASTRIC ACID secretion, as well as PEPSIN and GASTRIN output.Calcimycin: An ionophorous, polyether antibiotic from Streptomyces chartreusensis. It binds and transports CALCIUM and other divalent cations across membranes and uncouples oxidative phosphorylation while inhibiting ATPase of rat liver mitochondria. The substance is used mostly as a biochemical tool to study the role of divalent cations in various biological systems.Antibodies, Anti-Idiotypic: Antibodies which react with the individual structural determinants (idiotopes) on the variable region of other antibodies.Basophil Degranulation Test: An in vitro test used in the diagnosis of allergies including drug hypersensitivity. The allergen is added to the patient's white blood cells and the subsequent histamine release is measured.Cell Degranulation: The process of losing secretory granules (SECRETORY VESICLES). This occurs, for example, in mast cells, basophils, neutrophils, eosinophils, and platelets when secretory products are released from the granules by EXOCYTOSIS.Tartrazine: An anionic, hydrophilic azo dye with an orange-yellow color used in fabrics, foods and cosmetics, and as a biological stain.Histamine Agents: Drugs used for their actions on histaminergic systems. Included are drugs that act at histamine receptors, affect the life cycle of histamine, or affect the state of histaminergic cells.Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Guinea Pigs: A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.Diphenhydramine: A histamine H1 antagonist used as an antiemetic, antitussive, for dermatoses and pruritus, for hypersensitivity reactions, as a hypnotic, an antiparkinson, and as an ingredient in common cold preparations. It has some undesired antimuscarinic and sedative effects.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.SRS-A: A group of LEUKOTRIENES; (LTC4; LTD4; and LTE4) that is the major mediator of BRONCHOCONSTRICTION; HYPERSENSITIVITY; and other allergic reactions. Earlier studies described a "slow-reacting substance of ANAPHYLAXIS" released from lung by cobra venom or after anaphylactic shock. The relationship between SRS-A leukotrienes was established by UV which showed the presence of the conjugated triene. (From Merck Index, 11th ed)Ketotifen: A cycloheptathiophene blocker of histamine H1 receptors and release of inflammatory mediators. It has been proposed for the treatment of asthma, rhinitis, skin allergies, and anaphylaxis.Receptors, IgE: Specific molecular sites on the surface of B- and T-lymphocytes which combine with IgEs. Two subclasses exist: low affinity receptors (Fc epsilon RII) and high affinity receptors (Fc epsilon RI).Urticaria: A vascular reaction of the skin characterized by erythema and wheal formation due to localized increase of vascular permeability. The causative mechanism may be allergy, infection, or stress.ortho-Aminobenzoates: Benzoic acids, salts, or esters that contain an amino group attached to carbon number 2 or 6 of the benzene ring structure.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Hypersensitivity, Immediate: Hypersensitivity reactions which occur within minutes of exposure to challenging antigen due to the release of histamine which follows the antigen-antibody reaction and causes smooth muscle contraction and increased vascular permeability.Tryptases: A family of neutral serine proteases with TRYPSIN-like activity. Tryptases are primarily found in the SECRETORY GRANULES of MAST CELLS and are released during mast cell degranulation.Metiamide: A histamine H2 receptor antagonist that is used as an anti-ulcer agent.Ascaris: A genus of nematodes of the superfamily ASCARIDOIDEA whose species usually inhabit the intestine.Hypersensitivity: Altered reactivity to an antigen, which can result in pathologic reactions upon subsequent exposure to that particular antigen.Allergens: Antigen-type substances that produce immediate hypersensitivity (HYPERSENSITIVITY, IMMEDIATE).Rats, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.Gastric Acid: Hydrochloric acid present in GASTRIC JUICE.Enterochromaffin-like Cells: Neuroendocrine cells in the glands of the GASTRIC MUCOSA. They produce HISTAMINE and peptides such as CHROMOGRANINS. ECL cells respond to GASTRIN by releasing histamine which acts as a paracrine stimulator of the release of HYDROCHLORIC ACID from the GASTRIC PARIETAL CELLS.Pruritus: An intense itching sensation that produces the urge to rub or scratch the skin to obtain relief.Food Hypersensitivity: Gastrointestinal disturbances, skin eruptions, or shock due to allergic reactions to allergens in food.Terfenadine: A selective histamine H1-receptor antagonist devoid of central nervous system depressant activity. The drug was used for ALLERGY but withdrawn due to causing LONG QT SYNDROME.Gastric Fistula: Abnormal passage communicating with the STOMACH.Desensitization, Immunologic: Immunosuppression by the administration of increasing doses of antigen. Though the exact mechanism is not clear, the therapy results in an increase in serum levels of allergen-specific IMMUNOGLOBULIN G, suppression of specific IgE, and an increase in suppressor T-cell activity.Rhinitis, Allergic, Seasonal: Allergic rhinitis that occurs at the same time every year. It is characterized by acute CONJUNCTIVITIS with lacrimation and ITCHING, and regarded as an allergic condition triggered by specific ALLERGENS.Anaphylatoxins: Serum peptides derived from certain cleaved COMPLEMENT PROTEINS during COMPLEMENT ACTIVATION. They induce smooth MUSCLE CONTRACTION; mast cell HISTAMINE RELEASE; PLATELET AGGREGATION; and act as mediators of the local inflammatory process. The order of anaphylatoxin activity from the strongest to the weakest is C5a, C3a, C4a, and C5a des-arginine.Skin Tests: Epicutaneous or intradermal application of a sensitizer for demonstration of either delayed or immediate hypersensitivity. Used in diagnosis of hypersensitivity or as a test for cellular immunity.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Betahistine: A histamine analog and H1 receptor agonist that serves as a vasodilator. It is used in MENIERE DISEASE and in vascular headaches but may exacerbate bronchial asthma and peptic ulcers.Rats, Wistar: A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.Benzoylarginine Nitroanilide: A chromogenic substrate that permits direct measurement of peptide hydrolase activity, e.g., papain and trypsin, by colorimetry. The substrate liberates p-nitroaniline as a chromogenic product.Ascitic Fluid: The serous fluid of ASCITES, the accumulation of fluids in the PERITONEAL CAVITY.Oxymorphone: An opioid analgesic with actions and uses similar to those of MORPHINE, apart from an absence of cough suppressant activity. It is used in the treatment of moderate to severe pain, including pain in obstetrics. It may also be used as an adjunct to anesthesia. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1092)Leukocytes: White blood cells. These include granular leukocytes (BASOPHILS; EOSINOPHILS; and NEUTROPHILS) as well as non-granular leukocytes (LYMPHOCYTES and MONOCYTES).Lung: Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.Sneezing: The sudden, forceful, involuntary expulsion of air from the NOSE and MOUTH caused by irritation to the MUCOUS MEMBRANES of the upper RESPIRATORY TRACT.Theophylline: A methyl xanthine derivative from tea with diuretic, smooth muscle relaxant, bronchial dilation, cardiac and central nervous system stimulant activities. Theophylline inhibits the 3',5'-CYCLIC NUCLEOTIDE PHOSPHODIESTERASE that degrades CYCLIC AMP thus potentiates the actions of agents that act through ADENYLYL CYCLASES and cyclic AMP.Antigens: Substances that are recognized by the immune system and induce an immune reaction.Cetirizine: A potent second-generation histamine H1 antagonist that is effective in the treatment of allergic rhinitis, chronic urticaria, and pollen-induced asthma. Unlike many traditional antihistamines, it does not cause drowsiness or anticholinergic side effects.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Lasalocid: Cationic ionophore antibiotic obtained from Streptomyces lasaliensis that, among other effects, dissociates the calcium fluxes in muscle fibers. It is used as a coccidiostat, especially in poultry.Stimulation, Chemical: The increase in a measurable parameter of a PHYSIOLOGICAL PROCESS, including cellular, microbial, and plant; immunological, cardiovascular, respiratory, reproductive, urinary, digestive, neural, musculoskeletal, ocular, and skin physiological processes; or METABOLIC PROCESS, including enzymatic and other pharmacological processes, by a drug or other chemical.Skin: The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.Gastric Mucosa: Lining of the STOMACH, consisting of an inner EPITHELIUM, a middle LAMINA PROPRIA, and an outer MUSCULARIS MUCOSAE. The surface cells produce MUCUS that protects the stomach from attack by digestive acid and enzymes. When the epithelium invaginates into the LAMINA PROPRIA at various region of the stomach (CARDIA; GASTRIC FUNDUS; and PYLORUS), different tubular gastric glands are formed. These glands consist of cells that secrete mucus, enzymes, HYDROCHLORIC ACID, or hormones.Antigens, Plant: Substances found in PLANTS that have antigenic activity.Prostaglandins D: Physiologically active prostaglandins found in many tissues and organs. They show pressor activity, are mediators of inflammation, and have potential antithrombotic effects.Leukemia, Basophilic, Acute: A rare acute myeloid leukemia in which the primary differentiation is to BASOPHILS. It is characterized by an extreme increase of immature basophilic granulated cells in the bone marrow and blood. Mature basophils are usually sparse.Pollen: The fertilizing element of plants that contains the male GAMETOPHYTES.Digitoxigenin: 3 beta,14-Dihydroxy-5 beta-card-20(22)enolide. A cardenolide which is the aglycon of digitoxin. Synonyms: Cerberigenin; Echujetin; Evonogenin; Thevetigenin.Substance P: An eleven-amino acid neurotransmitter that appears in both the central and peripheral nervous systems. It is involved in transmission of PAIN, causes rapid contractions of the gastrointestinal smooth muscle, and modulates inflammatory and immune responses.Ionophores: Chemical agents that increase the permeability of biological or artificial lipid membranes to specific ions. Most ionophores are relatively small organic molecules that act as mobile carriers within membranes or coalesce to form ion permeable channels across membranes. Many are antibiotics, and many act as uncoupling agents by short-circuiting the proton gradient across mitochondrial membranes.Kinetics: The rate dynamics in chemical or physical systems.Pentagastrin: A synthetic pentapeptide that has effects like gastrin when given parenterally. It stimulates the secretion of gastric acid, pepsin, and intrinsic factor, and has been used as a diagnostic aid.Capillary Permeability: The property of blood capillary ENDOTHELIUM that allows for the selective exchange of substances between the blood and surrounding tissues and through membranous barriers such as the BLOOD-AIR BARRIER; BLOOD-AQUEOUS BARRIER; BLOOD-BRAIN BARRIER; BLOOD-NERVE BARRIER; BLOOD-RETINAL BARRIER; and BLOOD-TESTIS BARRIER. Small lipid-soluble molecules such as carbon dioxide and oxygen move freely by diffusion. Water and water-soluble molecules cannot pass through the endothelial walls and are dependent on microscopic pores. These pores show narrow areas (TIGHT JUNCTIONS) which may limit large molecule movement.Thiourea: A photographic fixative used also in the manufacture of resins. According to the Fourth Annual Report on Carcinogens (NTP 85-002, 1985), this substance may reasonably be anticipated to be a carcinogen (Merck Index, 9th ed). Many of its derivatives are ANTITHYROID AGENTS and/or FREE RADICAL SCAVENGERS.Cyclic AMP: An adenine nucleotide containing one phosphate group which is esterified to both the 3'- and 5'-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and ACTH.N-Formylmethionine Leucyl-Phenylalanine: A formylated tripeptide originally isolated from bacterial filtrates that is positively chemotactic to polymorphonuclear leucocytes, and causes them to release lysosomal enzymes and become metabolically activated.Bronchial Spasm: Spasmodic contraction of the smooth muscle of the bronchi.Neurotransmitter Agents: Substances used for their pharmacological actions on any aspect of neurotransmitter systems. Neurotransmitter agents include agonists, antagonists, degradation inhibitors, uptake inhibitors, depleters, precursors, and modulators of receptor function.Erythema: Redness of the skin produced by congestion of the capillaries. This condition may result from a variety of causes.Impromidine: A highly potent and specific histamine H2 receptor agonist. It has been used diagnostically as a gastric secretion indicator.Concanavalin A: A MANNOSE/GLUCOSE binding lectin isolated from the jack bean (Canavalia ensiformis). It is a potent mitogen used to stimulate cell proliferation in lymphocytes, primarily T-lymphocyte, cultures.Piperidines: A family of hexahydropyridines.Chymases: A family of neutral serine proteases with CHYMOTRYPSIN-like activity. Chymases are primarily found in the SECRETORY GRANULES of MAST CELLS and are released during mast cell degranulation.Gastrins: A family of gastrointestinal peptide hormones that excite the secretion of GASTRIC JUICE. They may also occur in the central nervous system where they are presumed to be neurotransmitters.Serotonin: A biochemical messenger and regulator, synthesized from the essential amino acid L-TRYPTOPHAN. In humans it is found primarily in the central nervous system, gastrointestinal tract, and blood platelets. Serotonin mediates several important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. Multiple receptor families (RECEPTORS, SEROTONIN) explain the broad physiological actions and distribution of this biochemical mediator.Thiamylal: A barbiturate that is administered intravenously for the production of complete anesthesia of short duration, for the induction of general anesthesia, or for inducing a hypnotic state. (From Martindale, The Extra Pharmacopoeia, 30th ed, p919)Complement C5: C5 plays a central role in both the classical and the alternative pathway of COMPLEMENT ACTIVATION. C5 is cleaved by C5 CONVERTASE into COMPLEMENT C5A and COMPLEMENT C5B. The smaller fragment C5a is an ANAPHYLATOXIN and mediator of inflammatory process. The major fragment C5b binds to the membrane initiating the spontaneous assembly of the late complement components, C5-C9, into the MEMBRANE ATTACK COMPLEX.Leukotrienes: A family of biologically active compounds derived from arachidonic acid by oxidative metabolism through the 5-lipoxygenase pathway. They participate in host defense reactions and pathophysiological conditions such as immediate hypersensitivity and inflammation. They have potent actions on many essential organs and systems, including the cardiovascular, pulmonary, and central nervous system as well as the gastrointestinal tract and the immune system.Prostaglandin D2: The principal cyclooxygenase metabolite of arachidonic acid. It is released upon activation of mast cells and is also synthesized by alveolar macrophages. Among its many biological actions, the most important are its bronchoconstrictor, platelet-activating-factor-inhibitory, and cytotoxic effects.Secretory Rate: The amount of a substance secreted by cells or by a specific organ or organism over a given period of time; usually applies to those substances which are formed by glandular tissues and are released by them into biological fluids, e.g., secretory rate of corticosteroids by the adrenal cortex, secretory rate of gastric acid by the gastric mucosa.Stomach: An organ of digestion situated in the left upper quadrant of the abdomen between the termination of the ESOPHAGUS and the beginning of the DUODENUM.Bronchi: The larger air passages of the lungs arising from the terminal bifurcation of the TRACHEA. They include the largest two primary bronchi which branch out into secondary bronchi, and tertiary bronchi which extend into BRONCHIOLES and PULMONARY ALVEOLI.Drug Hypersensitivity: Immunologically mediated adverse reactions to medicinal substances used legally or illegally.Phosphatidyl-N-Methylethanolamine N-Methyltransferase: An enzyme that catalyzes the METHYLATION of phosphatidyl-N-methylethanolamine to produce phosphatidyl-N-dimethylethanolamine. This enzyme can also methylate phosphatidyl-N-dimethylethanolamine to produce phosphatidyl-N-trimethylethanolamine (PHOSPHATIDYLCHOLINE).Microdialysis: A technique for measuring extracellular concentrations of substances in tissues, usually in vivo, by means of a small probe equipped with a semipermeable membrane. Substances may also be introduced into the extracellular space through the membrane.Trachea: The cartilaginous and membranous tube descending from the larynx and branching into the right and left main bronchi.Nasal Provocation Tests: Application of allergens to the nasal mucosa. Interpretation includes observation of nasal symptoms, rhinoscopy, and rhinomanometry. Nasal provocation tests are used in the diagnosis of nasal hypersensitivity, including RHINITIS, ALLERGIC, SEASONAL.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Humulus: A plant genus in the CANNABACEAE family. Best known for the buds of Humulus lupulus L. used in BEER.Muscle, Smooth: Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)Dimethindene: A histamine H1 antagonist. It is used in hypersensitivity reactions, in rhinitis, for pruritus, and in some common cold remedies.Parietal Cells, Gastric: Rounded or pyramidal cells of the GASTRIC GLANDS. They secrete HYDROCHLORIC ACID and produce gastric intrinsic factor, a glycoprotein that binds VITAMIN B12.Astemizole: Antihistamine drug now withdrawn from the market in many countries because of rare but potentially fatal side effects.Burimamide: An antagonist of histamine that appears to block both H2 and H3 histamine receptors. It has been used in the treatment of ulcers.Papaverine: An alkaloid found in opium but not closely related to the other opium alkaloids in its structure or pharmacological actions. It is a direct-acting smooth muscle relaxant used in the treatment of impotence and as a vasodilator, especially for cerebral vasodilation. The mechanism of its pharmacological actions is not clear, but it apparently can inhibit phosphodiesterases and it may have direct actions on calcium channels.Tosylphenylalanyl Chloromethyl Ketone: An inhibitor of Serine Endopeptidases. Acts as alkylating agent and is known to interfere with the translation process.Tubocurarine: A neuromuscular blocker and active ingredient in CURARE; plant based alkaloid of Menispermaceae.Datura stramonium: A plant species of the genus DATURA, family SOLANACEAE, that contains TROPANES and other SOLANACEOUS ALKALOIDS.Hypothalamic Area, Lateral: Area in the hypothalamus bounded medially by the mammillothalamic tract and the anterior column of the FORNIX (BRAIN). The medial edge of the INTERNAL CAPSULE and the subthalamic region form its lateral boundary. It contains the lateral hypothalamic nucleus, tuberomammillary nucleus, lateral tuberal nuclei, and fibers of the MEDIAL FOREBRAIN BUNDLE.Interleukin-3: A multilineage cell growth factor secreted by LYMPHOCYTES; EPITHELIAL CELLS; and ASTROCYTES which stimulates clonal proliferation and differentiation of various types of blood and tissue cells.Leukotriene C4: The conjugation product of LEUKOTRIENE A4 and glutathione. It is the major arachidonic acid metabolite in macrophages and human mast cells as well as in antigen-sensitized lung tissue. It stimulates mucus secretion in the lung, and produces contractions of nonvascular and some VASCULAR SMOOTH MUSCLE. (From Dictionary of Prostaglandins and Related Compounds, 1990)Peritoneum: A membrane of squamous EPITHELIAL CELLS, the mesothelial cells, covered by apical MICROVILLI that allow rapid absorption of fluid and particles in the PERITONEAL CAVITY. The peritoneum is divided into parietal and visceral components. The parietal peritoneum covers the inside of the ABDOMINAL WALL. The visceral peritoneum covers the intraperitoneal organs. The double-layered peritoneum forms the MESENTERY that suspends these organs from the abdominal wall.Ephedra: A plant genus of the family Ephedraceae, order Ephedrales, class Gnetopsida, division Gnetophyta.Depression, Chemical: The decrease in a measurable parameter of a PHYSIOLOGICAL PROCESS, including cellular, microbial, and plant; immunological, cardiovascular, respiratory, reproductive, urinary, digestive, neural, musculoskeletal, ocular, and skin physiological processes; or METABOLIC PROCESS, including enzymatic and other pharmacological processes, by a drug or other chemical.Forssman Antigen: A glycolipid, cross-species antigen that induces production of antisheep hemolysin. It is present on the tissue cells of many species but absent in humans. It is found in many infectious agents.Hydromorphone: An opioid analgesic made from MORPHINE and used mainly as an analgesic. It has a shorter duration of action than morphine.Muscle Contraction: A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.Isoproterenol: Isopropyl analog of EPINEPHRINE; beta-sympathomimetic that acts on the heart, bronchi, skeletal muscle, alimentary tract, etc. It is used mainly as bronchodilator and heart stimulant.Dose-Response Relationship, Immunologic: A specific immune response elicited by a specific dose of an immunologically active substance or cell in an organism, tissue, or cell.o-Phthalaldehyde: A reagent that forms fluorescent conjugation products with primary amines. It is used for the detection of many biogenic amines, peptides, and proteins in nanogram quantities in body fluids.Adenosine Triphosphate: An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.Tosyllysine Chloromethyl Ketone: An inhibitor of SERINE ENDOPEPTIDASES. Acts as an alkylating agent and is known to interfere with the translation process.Histamine H1 Antagonists, Non-Sedating: A class of non-sedating drugs that bind to but do not activate histamine receptors (DRUG INVERSE AGONISM), thereby blocking the actions of histamine or histamine agonists. These antihistamines represent a heterogenous group of compounds with differing chemical structures, adverse effects, distribution, and metabolism. Compared to the early (first generation) antihistamines, these non-sedating antihistamines have greater receptor specificity, lower penetration of BLOOD-BRAIN BARRIER, and are less likely to cause drowsiness or psychomotor impairment.Polyethyleneimine: Strongly cationic polymer that binds to certain proteins; used as a marker in immunology, to precipitate and purify enzymes and lipids. Synonyms: aziridine polymer; Epamine; Epomine; ethylenimine polymer; Montrek; PEI; Polymin(e).Dinitrophenols: Organic compounds that contain two nitro groups attached to a phenol.Dextrans: A group of glucose polymers made by certain bacteria. Dextrans are used therapeutically as plasma volume expanders and anticoagulants. They are also commonly used in biological experimentation and in industry for a wide variety of purposes.Delayed-Action Preparations: Dosage forms of a drug that act over a period of time by controlled-release processes or technology.Cytoplasmic Granules: Condensed areas of cellular material that may be bounded by a membrane.Asthma: A form of bronchial disorder with three distinct components: airway hyper-responsiveness (RESPIRATORY HYPERSENSITIVITY), airway INFLAMMATION, and intermittent AIRWAY OBSTRUCTION. It is characterized by spasmodic contraction of airway smooth muscle, WHEEZING, and dyspnea (DYSPNEA, PAROXYSMAL).