Adrenergic Agonists: Drugs that bind to and activate adrenergic receptors.Adrenergic alpha-Agonists: Drugs that selectively bind to and activate alpha adrenergic receptors.Adrenergic alpha-2 Receptor Agonists: Compounds that bind to and activate ADRENERGIC ALPHA-2 RECEPTORS.Clonidine: An imidazoline sympatholytic agent that stimulates ALPHA-2 ADRENERGIC RECEPTORS and central IMIDAZOLINE RECEPTORS. It is commonly used in the management of HYPERTENSION.Medetomidine: An agonist of RECEPTORS, ADRENERGIC ALPHA-2 that is used in veterinary medicine for its analgesic and sedative properties. It is the racemate of DEXMEDETOMIDINE.Adrenergic beta-Agonists: Drugs that selectively bind to and activate beta-adrenergic receptors.Adrenergic alpha-1 Receptor Agonists: Compounds that bind to and activate ADRENERGIC ALPHA-1 RECEPTORS.Phenylephrine: An alpha-1 adrenergic agonist used as a mydriatic, nasal decongestant, and cardiotonic agent.Clenbuterol: A substituted phenylaminoethanol that has beta-2 adrenomimetic properties at very low doses. It is used as a bronchodilator in asthma.Terbutaline: A selective beta-2 adrenergic agonist used as a bronchodilator and tocolytic.Receptors, Adrenergic, alpha: One of the two major pharmacological subdivisions of adrenergic receptors that were originally defined by the relative potencies of various adrenergic compounds. The alpha receptors were initially described as excitatory receptors that post-junctionally stimulate SMOOTH MUSCLE contraction. However, further analysis has revealed a more complex picture involving several alpha receptor subtypes and their involvement in feedback regulation.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.Metaproterenol: A beta-2 adrenergic agonist used in the treatment of ASTHMA and BRONCHIAL SPASM.Methoxamine: An alpha-1 adrenergic agonist that causes prolonged peripheral VASOCONSTRICTION.Adrenergic alpha-Antagonists: Drugs that bind to but do not activate alpha-adrenergic receptors thereby blocking the actions of endogenous or exogenous adrenergic agonists. Adrenergic alpha-antagonists are used in the treatment of hypertension, vasospasm, peripheral vascular disease, shock, and pheochromocytoma.Receptors, Adrenergic: Cell-surface proteins that bind epinephrine and/or norepinephrine with high affinity and trigger intracellular changes. The two major classes of adrenergic receptors, alpha and beta, were originally discriminated based on their cellular actions but now are distinguished by their relative affinity for characteristic synthetic ligands. Adrenergic receptors may also be classified according to the subtypes of G-proteins with which they bind; this scheme does not respect the alpha-beta distinction.Receptors, Adrenergic, alpha-2: A subclass of alpha-adrenergic receptors found on both presynaptic and postsynaptic membranes where they signal through Gi-Go G-PROTEINS. While postsynaptic alpha-2 receptors play a traditional role in mediating the effects of ADRENERGIC AGONISTS, the subset of alpha-2 receptors found on presynaptic membranes signal the feedback inhibition of NEUROTRANSMITTER release.Fenoterol: An adrenergic beta-2 agonist that is used as a bronchodilator and tocolytic.DioxolesEpinephrine: The active sympathomimetic hormone from the ADRENAL MEDULLA. It stimulates both the alpha- and beta- adrenergic systems, causes systemic VASOCONSTRICTION and gastrointestinal relaxation, stimulates the HEART, and dilates BRONCHI and cerebral vessels. It is used in ASTHMA and CARDIAC FAILURE and to delay absorption of local ANESTHETICS.Yohimbine: A plant alkaloid with alpha-2-adrenergic blocking activity. Yohimbine has been used as a mydriatic and in the treatment of ERECTILE DYSFUNCTION.Norepinephrine: Precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers and of the diffuse projection system in the brain arising from the locus ceruleus. It is also found in plants and is used pharmacologically as a sympathomimetic.Adrenergic beta-2 Receptor Agonists: Compounds bind to and activate ADRENERGIC BETA-2 RECEPTORS.Dexmedetomidine: A imidazole derivative that is an agonist of ADRENERGIC ALPHA-2 RECEPTORS. It is closely-related to MEDETOMIDINE, which is the racemic form of this compound.Receptors, Adrenergic, beta: One of two major pharmacologically defined classes of adrenergic receptors. The beta adrenergic receptors play an important role in regulating CARDIAC MUSCLE contraction, SMOOTH MUSCLE relaxation, and GLYCOGENOLYSIS.Procaterol: A long-acting beta-2-adrenergic receptor agonist.Nordefrin: A norepinephrine derivative used as a vasoconstrictor agent.Prazosin: A selective adrenergic alpha-1 antagonist used in the treatment of HEART FAILURE; HYPERTENSION; PHEOCHROMOCYTOMA; RAYNAUD DISEASE; PROSTATIC HYPERTROPHY; and URINARY RETENTION.Receptors, Adrenergic, beta-3: A subclass of beta-adrenergic receptors (RECEPTORS, ADRENERGIC, BETA). The beta-3 adrenergic receptors are the predominant beta-adrenergic receptor type expressed in white and brown ADIPOCYTES and are involved in modulating ENERGY METABOLISM and THERMOGENESIS.Receptors, Adrenergic, alpha-1: A subclass of alpha-adrenergic receptors that mediate contraction of SMOOTH MUSCLE in a variety of tissues such as ARTERIOLES; VEINS; and the UTERUS. They are usually found on postsynaptic membranes and signal through GQ-G11 G-PROTEINS.Adrenergic beta-3 Receptor Agonists: Compounds that bind to and activate ADRENERGIC BETA-3 RECEPTORS.Dopamine Agonists: Drugs that bind to and activate dopamine receptors.QuinoxalinesPropranolol: A widely used non-cardioselective beta-adrenergic antagonist. Propranolol has been used for MYOCARDIAL INFARCTION; ARRHYTHMIA; ANGINA PECTORIS; HYPERTENSION; HYPERTHYROIDISM; MIGRAINE; PHEOCHROMOCYTOMA; and ANXIETY but adverse effects instigate replacement by newer drugs.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Receptors, Adrenergic, beta-2: A subclass of beta-adrenergic receptors (RECEPTORS, ADRENERGIC, BETA). The adrenergic beta-2 receptors are more sensitive to EPINEPHRINE than to NOREPINEPHRINE and have a high affinity for the agonist TERBUTALINE. They are widespread, with clinically important roles in SKELETAL MUSCLE; LIVER; and vascular, bronchial, gastrointestinal, and genitourinary SMOOTH MUSCLE.Ethanolamines: AMINO ALCOHOLS containing the ETHANOLAMINE; (-NH2CH2CHOH) group and its derivatives.Sympathomimetics: Drugs that mimic the effects of stimulating postganglionic adrenergic sympathetic nerves. Included here are drugs that directly stimulate adrenergic receptors and drugs that act indirectly by provoking the release of adrenergic transmitters.Imidazoles: Compounds containing 1,3-diazole, a five membered aromatic ring containing two nitrogen atoms separated by one of the carbons. Chemically reduced ones include IMIDAZOLINES and IMIDAZOLIDINES. Distinguish from 1,2-diazole (PYRAZOLES).Guanfacine: A centrally acting antihypertensive agent with specificity towards ADRENERGIC ALPHA-2 RECEPTORS.Albuterol: A short-acting beta-2 adrenergic agonist that is primarily used as a bronchodilator agent to treat ASTHMA. Albuterol is prepared as a racemic mixture of R(-) and S(+) stereoisomers. The stereospecific preparation of R(-) isomer of albuterol is referred to as levalbuterol.Phenoxypropanolamines: Compounds based on a propanolamine attached via an OXYGEN atom to a phenoxy ring. The side chain is one carbon longer than PHENYLETHYLAMINES.Idazoxan: A benzodioxane-linked imidazole that has alpha-2 adrenoceptor antagonist activity.Xylazine: An adrenergic alpha-2 agonist used as a sedative, analgesic and centrally acting muscle relaxant in VETERINARY MEDICINE.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.Dioxanes: 1,4-Diethylene dioxides. Industrial solvents. According to the Fourth Annual Report on Carcinogens (NTP 85-002, 1985), dioxane itself may "reasonably be anticipated to be a carcinogen." (Merck Index, 11th ed)Adipose Tissue, Brown: A thermogenic form of adipose tissue composed of BROWN ADIPOCYTES. It is found in newborns of many species including humans, and in hibernating mammals. Brown fat is richly vascularized, innervated, and densely packed with MITOCHONDRIA which can generate heat directly from the stored lipids.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.Adrenergic beta-Antagonists: Drugs that bind to but do not activate beta-adrenergic receptors thereby blocking the actions of beta-adrenergic agonists. Adrenergic beta-antagonists are used for treatment of hypertension, cardiac arrhythmias, angina pectoris, glaucoma, migraine headaches, and anxiety.Autonomic Agents: Agents affecting the function of, or mimicking the actions of, the autonomic nervous system and thereby having an effect on such processes as respiration, circulation, digestion, body temperature regulation, certain endocrine gland secretions, etc.Midodrine: An ethanolamine derivative that is an adrenergic alpha-1 agonist. It is used as a vasoconstrictor agent in the treatment of HYPOTENSION.Cholinergic Agonists: Drugs that bind to and activate cholinergic receptors.Cyclic CMP: A cyclic nucleotide formed from CYTIDINE TRIPHOSPHATE by the action of cytidylate cyclase. It is a potential cyclic nucleotide intracellular mediator of signal transductions.Hypnotics and Sedatives: Drugs used to induce drowsiness or sleep or to reduce psychological excitement or anxiety.Propanolamines: AMINO ALCOHOLS containing the propanolamine (NH2CH2CHOHCH2) group and its derivatives.Injections, Spinal: Introduction of therapeutic agents into the spinal region using a needle and syringe.Sympatholytics: Drugs that inhibit the actions of the sympathetic nervous system by any mechanism. The most common of these are the ADRENERGIC ANTAGONISTS and drugs that deplete norepinephrine or reduce the release of transmitters from adrenergic postganglionic terminals (see ADRENERGIC AGENTS). Drugs that act in the central nervous system to reduce sympathetic activity (e.g., centrally acting alpha-2 adrenergic agonists, see ADRENERGIC ALPHA-AGONISTS) are included here.GABA Agonists: Endogenous compounds and drugs that bind to and activate GAMMA-AMINOBUTYRIC ACID receptors (RECEPTORS, GABA).Phentolamine: A nonselective alpha-adrenergic antagonist. It is used in the treatment of hypertension and hypertensive emergencies, pheochromocytoma, vasospasm of RAYNAUD DISEASE and frostbite, clonidine withdrawal syndrome, impotence, and peripheral vascular disease.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.Dihydroalprenolol: Hydrogenated alprenolol derivative where the extra hydrogens are often tritiated. This radiolabeled form of ALPRENOLOL, a beta-adrenergic blocker, is used to label the beta-adrenergic receptor for isolation and study.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.Purinergic P1 Receptor Agonists: Compounds that bind to and stimulate PURINERGIC P1 RECEPTORS.PhenoxyacetatesCarbachol: A slowly hydrolyzed CHOLINERGIC AGONIST that acts at both MUSCARINIC RECEPTORS and NICOTINIC RECEPTORS.Fluocinolone Acetonide: A glucocorticoid derivative used topically in the treatment of various skin disorders. It is usually employed as a cream, gel, lotion, or ointment. It has also been used topically in the treatment of inflammatory eye, ear, and nose disorders. (From Martindale, The Extra Pharmacopoeia, 30th ed, p732)Alprenolol: One of the ADRENERGIC BETA-ANTAGONISTS used as an antihypertensive, anti-anginal, and anti-arrhythmic agent.Lacrimal Apparatus: The tear-forming and tear-conducting system which includes the lacrimal glands, eyelid margins, conjunctival sac, and the tear drainage system.Adrenergic Agents: Drugs that act on adrenergic receptors or affect the life cycle of adrenergic transmitters. Included here are adrenergic agonists and antagonists and agents that affect the synthesis, storage, uptake, metabolism, or release of adrenergic transmitters.Muscarinic Agonists: Drugs that bind to and activate muscarinic cholinergic receptors (RECEPTORS, MUSCARINIC). Muscarinic agonists are most commonly used when it is desirable to increase smooth muscle tone, especially in the GI tract, urinary bladder and the eye. They may also be used to reduce heart rate.Pertussis Toxin: One of the virulence factors produced by BORDETELLA PERTUSSIS. It is a multimeric protein composed of five subunits S1 - S5. S1 contains mono ADPribose transferase activity.Adrenergic Antagonists: Drugs that bind to but do not activate ADRENERGIC RECEPTORS. Adrenergic antagonists block the actions of the endogenous adrenergic transmitters EPINEPHRINE and NOREPINEPHRINE.Catecholamines: A general class of ortho-dihydroxyphenylalkylamines derived from tyrosine.Nicotinic Agonists: Drugs that bind to and activate nicotinic cholinergic receptors (RECEPTORS, NICOTINIC). Nicotinic agonists act at postganglionic nicotinic receptors, at neuroeffector junctions in the peripheral nervous system, and at nicotinic receptors in the central nervous system. Agents that function as neuromuscular depolarizing blocking agents are included here because they activate nicotinic receptors, although they are used clinically to block nicotinic transmission.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.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.Drug Interactions: The action of a drug that may affect the activity, metabolism, or toxicity of another drug.Parasympathomimetics: Drugs that mimic the effects of parasympathetic nervous system activity. Included here are drugs that directly stimulate muscarinic receptors and drugs that potentiate cholinergic activity, usually by slowing the breakdown of acetylcholine (CHOLINESTERASE INHIBITORS). Drugs that stimulate both sympathetic and parasympathetic postganglionic neurons (GANGLIONIC STIMULANTS) are not included here.Colforsin: Potent activator of the adenylate cyclase system and the biosynthesis of cyclic AMP. From the plant COLEUS FORSKOHLII. Has antihypertensive, positive inotropic, platelet aggregation inhibitory, and smooth muscle relaxant activities; also lowers intraocular pressure and promotes release of hormones from the pituitary gland.Serotonin 5-HT2 Receptor Agonists: Endogenous compounds and drugs that specifically stimulate SEROTONIN 5-HT2 RECEPTORS. Included under this heading are agonists for one or more of the specific 5-HT2 receptor subtypes.Vasopressins: Antidiuretic hormones released by the NEUROHYPOPHYSIS of all vertebrates (structure varies with species) to regulate water balance and OSMOLARITY. In general, vasopressin is a nonapeptide consisting of a six-amino-acid ring with a cysteine 1 to cysteine 6 disulfide bridge or an octapeptide containing a CYSTINE. All mammals have arginine vasopressin except the pig with a lysine at position 8. Vasopressin, a vasoconstrictor, acts on the KIDNEY COLLECTING DUCTS to increase water reabsorption, increase blood volume and blood pressure.Virulence Factors, Bordetella: A set of BACTERIAL ADHESINS and TOXINS, BIOLOGICAL produced by BORDETELLA organisms that determine the pathogenesis of BORDETELLA INFECTIONS, such as WHOOPING COUGH. They include filamentous hemagglutinin; FIMBRIAE PROTEINS; pertactin; PERTUSSIS TOXIN; ADENYLATE CYCLASE TOXIN; dermonecrotic toxin; tracheal cytotoxin; Bordetella LIPOPOLYSACCHARIDES; and tracheal colonization factor.Serotonin 5-HT1 Receptor Agonists: Endogenous compounds and drugs that specifically stimulate SEROTONIN 5-HT1 RECEPTORS. Included under this heading are agonists for one or more of the specific 5-HT1 receptor subtypes.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)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.Ciliary Body: A ring of tissue extending from the scleral spur to the ora serrata of the RETINA. It consists of the uveal portion and the epithelial portion. The ciliary muscle is in the uveal portion and the ciliary processes are in the epithelial portion.Adenylate Cyclase: An enzyme of the lyase class that catalyzes the formation of CYCLIC AMP and pyrophosphate from ATP. EC P2 Receptor Agonists: Compounds that bind to and stimulate PURINERGIC P2 RECEPTORS.Adenylate Cyclase Toxin: One of the virulence factors produced by virulent BORDETELLA organisms. It is a bifunctional protein with both ADENYLYL CYCLASES and hemolysin components.Locus Coeruleus: Bluish-colored region in the superior angle of the FOURTH VENTRICLE floor, corresponding to melanin-like pigmented nerve cells which lie lateral to the PERIAQUEDUCTAL GRAY.Phenoxybenzamine: An alpha-adrenergic antagonist with long duration of action. It has been used to treat hypertension and as a peripheral vasodilator.Lipolysis: The metabolic process of breaking down LIPIDS to release FREE FATTY ACIDS, the major oxidative fuel for the body. Lipolysis may involve dietary lipids in the DIGESTIVE TRACT, circulating lipids in the BLOOD, and stored lipids in the ADIPOSE TISSUE or the LIVER. A number of enzymes are involved in such lipid hydrolysis, such as LIPASE and LIPOPROTEIN LIPASE from various tissues.GABA-A Receptor Agonists: Endogenous compounds and drugs that bind to and activate GABA-A RECEPTORS.Body Fluids: Liquid components of living organisms.Analgesics, Non-Narcotic: A subclass of analgesic agents that typically do not bind to OPIOID RECEPTORS and are not addictive. Many non-narcotic analgesics are offered as NONPRESCRIPTION DRUGS.Adrenergic alpha-1 Receptor Antagonists: Drugs that bind to and block the activation of ADRENERGIC ALPHA-1 RECEPTORS.Bucladesine: A cyclic nucleotide derivative that mimics the action of endogenous CYCLIC AMP and is capable of permeating the cell membrane. It has vasodilator properties and is used as a cardiac stimulant. (From Merck Index, 11th ed)Triamcinolone: A glucocorticoid given, as the free alcohol or in esterified form, orally, intramuscularly, by local injection, by inhalation, or applied topically in the management of various disorders in which corticosteroids are indicated. (From Martindale, The Extra Pharmacopoeia, 30th ed, p739)Acetylcholine: A neurotransmitter found at neuromuscular junctions, autonomic ganglia, parasympathetic effector junctions, a subset of sympathetic effector junctions, and at many sites in the central nervous system.Bronchodilator Agents: Agents that cause an increase in the expansion of a bronchus or bronchial tubes.Naloxone: A specific opiate antagonist that has no agonist activity. It is a competitive antagonist at mu, delta, and kappa opioid receptors.Azepines: Seven membered heterocyclic rings containing a NITROGEN atom.Adenosine A1 Receptor Agonists: Compounds that bind to and stimulate ADENOSINE A1 RECEPTORS.Signal Transduction: The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.RNA, Messenger: RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Myocardium: The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.Blood Pressure: PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.GTP-Binding Proteins: Regulatory proteins that act as molecular switches. They control a wide range of biological processes including: receptor signaling, intracellular signal transduction pathways, and protein synthesis. Their activity is regulated by factors that control their ability to bind to and hydrolyze GTP to GDP. EC 3.6.1.-.Mitochondrial Proteins: Proteins encoded by the mitochondrial genome or proteins encoded by the nuclear genome that are imported to and resident in the MITOCHONDRIA.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.Vasoconstriction: The physiological narrowing of BLOOD VESSELS by contraction of the VASCULAR SMOOTH MUSCLE.Kinetics: The rate dynamics in chemical or physical systems.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.Heart Rate: The number of times the HEART VENTRICLES contract per unit of time, usually per minute.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.Analgesics: Compounds capable of relieving pain without the loss of CONSCIOUSNESS.Excitatory Amino Acid Agonists: Drugs that bind to and activate excitatory amino acid receptors.Ion Channels: Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.Hemodynamics: The movement and the forces involved in the movement of the blood through the CARDIOVASCULAR SYSTEM.Glucagon: A 29-amino acid pancreatic peptide derived from proglucagon which is also the precursor of intestinal GLUCAGON-LIKE PEPTIDES. Glucagon is secreted by PANCREATIC ALPHA CELLS and plays an important role in regulation of BLOOD GLUCOSE concentration, ketone metabolism, and several other biochemical and physiological processes. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p1511)Cannabinoid Receptor Agonists: Compounds that interact with and stimulate the activity of CANNABINOID RECEPTORS.Enzyme Inhibitors: Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.Protein Kinase C: An serine-threonine protein kinase that requires the presence of physiological concentrations of CALCIUM and membrane PHOSPHOLIPIDS. The additional presence of DIACYLGLYCEROLS markedly increases its sensitivity to both calcium and phospholipids. The sensitivity of the enzyme can also be increased by PHORBOL ESTERS and it is believed that protein kinase C is the receptor protein of tumor-promoting phorbol esters.Heart: The hollow, muscular organ that maintains the circulation of the blood.Receptors, Opioid, mu: A class of opioid receptors recognized by its pharmacological profile. Mu opioid receptors bind, in decreasing order of affinity, endorphins, dynorphins, met-enkephalin, and leu-enkephalin. They have also been shown to be molecular receptors for morphine.Sheep: Any of the ruminant mammals with curved horns in the genus Ovis, family Bovidae. They possess lachrymal grooves and interdigital glands, which are absent in GOATS.Vasoactive Intestinal Peptide: A highly basic, 28 amino acid neuropeptide released from intestinal mucosa. It has a wide range of biological actions affecting the cardiovascular, gastrointestinal, and respiratory systems and is neuroprotective. It binds special receptors (RECEPTORS, VASOACTIVE INTESTINAL PEPTIDE).Sympathetic Nervous System: The thoracolumbar division of the autonomic nervous system. Sympathetic preganglionic fibers originate in neurons of the intermediolateral column of the spinal cord and project to the paravertebral and prevertebral ganglia, which in turn project to target organs. The sympathetic nervous system mediates the body's response to stressful situations, i.e., the fight or flight reactions. It often acts reciprocally to the parasympathetic system.Administration, Inhalation: The administration of drugs by the respiratory route. It includes insufflation into the respiratory tract.Insulin: A 51-amino acid pancreatic hormone that plays a major role in the regulation of glucose metabolism, directly by suppressing endogenous glucose production (GLYCOGENOLYSIS; GLUCONEOGENESIS) and indirectly by suppressing GLUCAGON secretion and LIPOLYSIS. Native insulin is a globular protein comprised of a zinc-coordinated hexamer. Each insulin monomer containing two chains, A (21 residues) and B (30 residues), linked by two disulfide bonds. Insulin is used as a drug to control insulin-dependent diabetes mellitus (DIABETES MELLITUS, TYPE 1).Adenosine A3 Receptor Agonists: Drugs that selectively bind to and activate ADENOSINE A3 RECEPTORS.Vasoconstrictor Agents: Drugs used to cause constriction of the blood vessels.Animals, Newborn: Refers to animals in the period of time just after birth.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Pulmonary Edema: Excessive accumulation of extravascular fluid in the lung, an indication of a serious underlying disease or disorder. Pulmonary edema prevents efficient PULMONARY GAS EXCHANGE in the PULMONARY ALVEOLI, and can be life-threatening.Receptors, Opioid, kappa: A class of opioid receptors recognized by its pharmacological profile. Kappa opioid receptors bind dynorphins with a higher affinity than endorphins which are themselves preferred to enkephalins.Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Mice, Inbred C57BLAdministration, Topical: The application of drug preparations to the surfaces of the body, especially the skin (ADMINISTRATION, CUTANEOUS) or mucous membranes. This method of treatment is used to avoid systemic side effects when high doses are required at a localized area or as an alternative systemic administration route, to avoid hepatic processing for example.Pulmonary Alveoli: Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place.Analysis of Variance: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.Spinal Cord: A cylindrical column of tissue that lies within the vertebral canal. It is composed of WHITE MATTER and GRAY MATTER.Radioligand Assay: Quantitative determination of receptor (binding) proteins in body fluids or tissue using radioactively labeled binding reagents (e.g., antibodies, intracellular receptors, plasma binders).Drug Synergism: The action of a drug in promoting or enhancing the effectiveness of another drug.Enzyme Activation: Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.Nitric Oxide: A free radical gas produced endogenously by a variety of mammalian cells, synthesized from ARGININE by NITRIC OXIDE SYNTHASE. Nitric oxide is one of the ENDOTHELIUM-DEPENDENT RELAXING FACTORS released by the vascular endothelium and mediates VASODILATION. It also inhibits platelet aggregation, induces disaggregation of aggregated platelets, and inhibits platelet adhesion to the vascular endothelium. Nitric oxide activates cytosolic GUANYLATE CYCLASE and thus elevates intracellular levels of CYCLIC GMP.Reflex: An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.Adipose Tissue: Specialized connective tissue composed of fat cells (ADIPOCYTES). It is the site of stored FATS, usually in the form of TRIGLYCERIDES. In mammals, there are two types of adipose tissue, the WHITE FAT and the BROWN FAT. Their relative distributions vary in different species with most adipose tissue being white.GABA-B Receptor Agonists: Endogenous compounds and drugs that bind to and activate GABA-B RECEPTORS.Cyclic AMP-Dependent Protein Kinases: A group of enzymes that are dependent on CYCLIC AMP and catalyze the phosphorylation of SERINE or THREONINE residues on proteins. Included under this category are two cyclic-AMP-dependent protein kinase subtypes, each of which is defined by its subunit composition.Receptors, Opioid, delta: A class of opioid receptors recognized by its pharmacological profile. Delta opioid receptors bind endorphins and enkephalins with approximately equal affinity and have less affinity for dynorphins.Body Temperature Regulation: The processes of heating and cooling that an organism uses to control its temperature.Serotonin 5-HT4 Receptor Agonists: Endogenous compounds and drugs that specifically stimulate SEROTONIN 5-HT4 RECEPTORS.Ligands: A molecule that binds to another molecule, used especially to refer to a small molecule that binds specifically to a larger molecule, e.g., an antigen binding to an antibody, a hormone or neurotransmitter binding to a receptor, or a substrate or allosteric effector binding to an enzyme. Ligands are also molecules that donate or accept a pair of electrons to form a coordinate covalent bond with the central metal atom of a coordination complex. (From Dorland, 27th ed)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.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).Membrane Potentials: The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).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.Amiloride: A pyrazine compound inhibiting SODIUM reabsorption through SODIUM CHANNELS in renal EPITHELIAL CELLS. This inhibition creates a negative potential in the luminal membranes of principal cells, located in the distal convoluted tubule and collecting duct. Negative potential reduces secretion of potassium and hydrogen ions. Amiloride is used in conjunction with DIURETICS to spare POTASSIUM loss. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p705)Carrier Proteins: Transport proteins that carry specific substances in the blood or across cell membranes.Chlorides: Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.Receptors, Dopamine D2: A subfamily of G-PROTEIN-COUPLED RECEPTORS that bind the neurotransmitter DOPAMINE and modulate its effects. D2-class receptor genes contain INTRONS, and the receptors inhibit ADENYLYL CYCLASES.Mesenteric Arteries: Arteries which arise from the abdominal aorta and distribute to most of the intestines.Regional Blood Flow: The flow of BLOOD through or around an organ or region of the body.Phosphorylation: The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Double-Blind Method: A method of studying a drug or procedure in which both the subjects and investigators are kept unaware of who is actually getting which specific treatment.Enkephalin, Ala(2)-MePhe(4)-Gly(5)-: An enkephalin analog that selectively binds to the MU OPIOID RECEPTOR. It is used as a model for drug permeability experiments.Glucose: A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement.Purinergic Agonists: Compounds that bind to and activate PURINERGIC RECEPTORS.Halothane: A nonflammable, halogenated, hydrocarbon anesthetic that provides relatively rapid induction with little or no excitement. Analgesia may not be adequate. NITROUS OXIDE is often given concomitantly. Because halothane may not produce sufficient muscle relaxation, supplemental neuromuscular blocking agents may be required. (From AMA Drug Evaluations Annual, 1994, p178)Body Weight: The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms.Adenosine: A nucleoside that is composed of ADENINE and D-RIBOSE. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter.Perfusion: Treatment process involving the injection of fluid into an organ or tissue.Muscle, Smooth, Vascular: The nonstriated involuntary muscle tissue of blood vessels.Mice, Knockout: Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.Pain: An unpleasant sensation induced by noxious stimuli which are detected by NERVE ENDINGS of NOCICEPTIVE NEURONS.Gene Expression Regulation: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.Receptors, Opioid: Cell membrane proteins that bind opioids and trigger intracellular changes which influence the behavior of cells. The endogenous ligands for opioid receptors in mammals include three families of peptides, the enkephalins, endorphins, and dynorphins. The receptor classes include mu, delta, and kappa receptors. Sigma receptors bind several psychoactive substances, including certain opioids, but their endogenous ligands are not known.Adrenergic beta-1 Receptor Agonists: Compounds that bind to and activate ADRENERGIC BETA-1 RECEPTORS.Piperidines: A family of hexahydropyridines.Serotonin Antagonists: Drugs that bind to but do not activate serotonin receptors, thereby blocking the actions of serotonin or SEROTONIN RECEPTOR AGONISTS.Glucocorticoids: A group of CORTICOSTEROIDS that affect carbohydrate metabolism (GLUCONEOGENESIS, liver glycogen deposition, elevation of BLOOD SUGAR), inhibit ADRENOCORTICOTROPIC HORMONE secretion, and possess pronounced anti-inflammatory activity. They also play a role in fat and protein metabolism, maintenance of arterial blood pressure, alteration of the connective tissue response to injury, reduction in the number of circulating lymphocytes, and functioning of the central nervous system.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.Calcium Channel Agonists: Agents that increase calcium influx into calcium channels of excitable tissues. This causes vasoconstriction in VASCULAR SMOOTH MUSCLE and/or CARDIAC MUSCLE cells as well as stimulation of insulin release from pancreatic islets. Therefore, tissue-selective calcium agonists have the potential to combat cardiac failure and endocrinological disorders. They have been used primarily in experimental studies in cell and tissue culture.Adipocytes: Cells in the body that store FATS, usually in the form of TRIGLYCERIDES. WHITE ADIPOCYTES are the predominant type and found mostly in the abdominal cavity and subcutaneous tissue. BROWN ADIPOCYTES are thermogenic cells that can be found in newborns of some species and hibernating mammals.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine: A selective D1 dopamine receptor agonist used primarily as a research tool.Phenethylamines: A group of compounds that are derivatives of beta- aminoethylbenzene which is structurally and pharmacologically related to amphetamine. (From Merck Index, 11th ed)CHO Cells: CELL LINE derived from the ovary of the Chinese hamster, Cricetulus griseus (CRICETULUS). The species is a favorite for cytogenetic studies because of its small chromosome number. The cell line has provided model systems for the study of genetic alterations in cultured mammalian cells.Vasodilator Agents: Drugs used to cause dilation of the blood vessels.Binding, Competitive: The interaction of two or more substrates or ligands with the same binding site. The displacement of one by the other is used in quantitative and selective affinity measurements.Cannabinoids: Compounds having the cannabinoid structure. They were originally extracted from Cannabis sativa L. The most pharmacologically active constituents are TETRAHYDROCANNABINOL; CANNABINOL; and CANNABIDIOL.Receptors, Purinergic P1: A class of cell surface receptors that prefer ADENOSINE to other endogenous PURINES. Purinergic P1 receptors are widespread in the body including the cardiovascular, respiratory, immune, and nervous systems. There are at least two pharmacologically distinguishable types (A1 and A2, or Ri and Ra).Cyclic GMP: Guanosine cyclic 3',5'-(hydrogen phosphate). A guanine nucleotide containing one phosphate group which is esterified to the sugar moiety in both the 3'- and 5'-positions. It is a cellular regulatory agent and has been described as a second messenger. Its levels increase in response to a variety of hormones, including acetylcholine, insulin, and oxytocin and it has been found to activate specific protein kinases. (From Merck Index, 11th ed)Quinpirole: A dopamine D2/D3 receptor agonist.Cricetinae: A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.Biological Transport: The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.Tetrahydronaphthalenes: Partially saturated 1,2,3,4-tetrahydronaphthalene compounds.