Cromakalim: A potassium-channel opening vasodilator that has been investigated in the management of hypertension. It has also been tried in patients with asthma. (Martindale, The Extra Pharmacopoeia, 30th ed, p352)Benzopyrans: Compounds with a core of fused benzo-pyran rings.Pyrroles: Azoles of one NITROGEN and two double bonds that have aromatic chemical properties.Potassium Radioisotopes: Unstable isotopes of potassium that decay or disintegrate emitting radiation. K atoms with atomic weights 37, 38, 40, and 42-45 are radioactive potassium isotopes.Glyburide: An antidiabetic sulfonylurea derivative with actions similar to those of chlorpropamide.Pinacidil: A guanidine that opens POTASSIUM CHANNELS producing direct peripheral vasodilatation of the ARTERIOLES. It reduces BLOOD PRESSURE and peripheral resistance and produces fluid retention. (Martindale The Extra Pharmacopoeia, 31st ed)Minoxidil: A potent direct-acting peripheral vasodilator (VASODILATOR AGENTS) that reduces peripheral resistance and produces a fall in BLOOD PRESSURE. (From Martindale, The Extra Pharmacopoeia, 30th ed, p371)Rubidium Radioisotopes: Unstable isotopes of rubidium that decay or disintegrate emitting radiation. Rb atoms with atomic weights 79-84, and 86-95 are radioactive rubidium isotopes.Nicorandil: A derivative of the NIACINAMIDE that is structurally combined with an organic nitrate. It is a potassium-channel opener that causes vasodilatation of arterioles and large coronary arteries. Its nitrate-like properties produce venous vasodilation through stimulation of guanylate cyclase.Potassium Channels: Cell membrane glycoproteins that are selectively permeable to potassium ions. At least eight major groups of K channels exist and they are made up of dozens of different subunits.Parasympatholytics: Agents that inhibit the actions of the parasympathetic nervous system. The major group of drugs used therapeutically for this purpose is the MUSCARINIC ANTAGONISTS.Diazoxide: A benzothiadiazine derivative that is a peripheral vasodilator used for hypertensive emergencies. It lacks diuretic effect, apparently because it lacks a sulfonamide group.Vasodilator Agents: Drugs used to cause dilation of the blood vessels.Guanidines: A family of iminourea derivatives. The parent compound has been isolated from mushrooms, corn germ, rice hulls, mussels, earthworms, and turnip juice. Derivatives may have antiviral and antifungal properties.Picolines: A group of compounds that are monomethyl derivatives of pyridines. (From Dorland, 28th ed)Muscle Relaxation: That phase of a muscle twitch during which a muscle returns to a resting position.Nifedipine: A potent vasodilator agent with calcium antagonistic action. It is a useful anti-anginal agent that also lowers blood pressure.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.Niacinamide: An important compound functioning as a component of the coenzyme NAD. Its primary significance is in the prevention and/or cure of blacktongue and PELLAGRA. Most animals cannot manufacture this compound in amounts sufficient to prevent nutritional deficiency and it therefore must be supplemented through dietary intake.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.KATP Channels: Heteromultimers of Kir6 channels (the pore portion) and sulfonylurea receptor (the regulatory portion) which affect function of the HEART; PANCREATIC BETA CELLS; and KIDNEY COLLECTING DUCTS. KATP channel blockers include GLIBENCLAMIDE and mitiglinide whereas openers include CROMAKALIM and minoxidil sulfate.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.Aorta, Thoracic: The portion of the descending aorta proceeding from the arch of the aorta and extending to the DIAPHRAGM, eventually connecting to the ABDOMINAL AORTA.Charybdotoxin: A 37-amino acid residue peptide isolated from the scorpion Leiurus quinquestriatus hebraeus. It is a neurotoxin that inhibits calcium activated potassium channels.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)Trachea: The cartilaginous and membranous tube descending from the larynx and branching into the right and left main bronchi.Decanoic Acids: 10-carbon saturated monocarboxylic acids.Hydroxy Acids: Organic compounds containing both the hydroxyl and carboxyl radicals.Muscle, Smooth, Vascular: The nonstriated involuntary muscle tissue of blood vessels.PyransPotassium: An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.Rubidium: An element that is an alkali metal. It has an atomic symbol Rb, atomic number 37, and atomic weight 85.47. It is used as a chemical reagent and in the manufacture of photoelectric cells.Microelectrodes: Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)Nitroprusside: A powerful vasodilator used in emergencies to lower blood pressure or to improve cardiac function. It is also an indicator for free sulfhydryl groups in proteins.Vasodilation: The physiological widening of BLOOD VESSELS by relaxing the underlying VASCULAR SMOOTH MUSCLE.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).Parasympathetic Nervous System: The craniosacral division of the autonomic nervous system. The cell bodies of the parasympathetic preganglionic fibers are in brain stem nuclei and in the sacral spinal cord. They synapse in cranial autonomic ganglia or in terminal ganglia near target organs. The parasympathetic nervous system generally acts to conserve resources and restore homeostasis, often with effects reciprocal to the sympathetic nervous system.Ureter: One of a pair of thick-walled tubes that transports urine from the KIDNEY PELVIS to the URINARY BLADDER.Sulfonylurea CompoundsNitroglycerin: A volatile vasodilator which relieves ANGINA PECTORIS by stimulating GUANYLATE CYCLASE and lowering cytosolic calcium. It is also sometimes used for TOCOLYSIS and explosives.Potassium Channel Blockers: A class of drugs that act by inhibition of potassium efflux through cell membranes. Blockade of potassium channels prolongs the duration of ACTION POTENTIALS. They are used as ANTI-ARRHYTHMIA AGENTS and VASODILATOR AGENTS.Tetraethylammonium CompoundsBromates: Negative ions or salts derived from bromic acid, HBrO3.Encyclopedias as Topic: Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)Terminology as Topic: The terms, expressions, designations, or symbols used in a particular science, discipline, or specialized subject area.Safety: Freedom from exposure to danger and protection from the occurrence or risk of injury or loss. It suggests optimal precautions in the workplace, on the street, in the home, etc., and includes personal safety as well as the safety of property.Accidents, Occupational: Unforeseen occurrences, especially injuries in the course of work-related activities.Databases, Chemical: Databases devoted to knowledge about specific chemicals.Pharmacopoeias as Topic: Authoritative treatises on drugs and preparations, their description, formulation, analytic composition, physical constants, main chemical properties used in identification, standards for strength, purity, and dosage, chemical tests for determining identity and purity, etc. They are usually published under governmental jurisdiction (e.g., USP, the United States Pharmacopoeia; BP, British Pharmacopoeia; P. Helv., the Swiss Pharmacopoeia). They differ from FORMULARIES in that they are far more complete: formularies tend to be mere listings of formulas and prescriptions.Cyclic S-OxidesAdministration, 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.Prostaglandins F, Synthetic: Analogs or derivatives of prostaglandins F that do not occur naturally in the body. They do not include the product of the chemical synthesis of hormonal PGF.Cloprostenol: A synthetic prostaglandin F2alpha analog. The compound has luteolytic effects and is used for the synchronization of estrus in cattle.BenzophenonesIntraocular Pressure: The pressure of the fluids in the eye.