Barium Sulfate: A compound used as an x-ray contrast medium that occurs in nature as the mineral barite. It is also used in various manufacturing applications and mixed into heavy concrete to serve as a radiation shield.Barium: An element of the alkaline earth group of metals. It has an atomic symbol Ba, atomic number 56, and atomic weight 138. All of its acid-soluble salts are poisonous.Barium Compounds: Inorganic compounds that contain barium as an integral part of the molecule.Enema: A solution or compound that is introduced into the RECTUM with the purpose of cleansing the COLON or for diagnostic procedures.Strontium: An element of the alkaline earth family of metals. It has the atomic symbol Sr, atomic number 38, and atomic weight 87.62.Diverticulum, Colon: A pouch or sac opening from the COLON.Sigmoidoscopy: Endoscopic examination, therapy or surgery of the sigmoid flexure.Macrocystis: A genus of BROWN ALGAE in the family Lessoniaceae, and one of the major forms of KELP. The species Macrocystis pyrifera, also known as giant kelp, is the largest of the marine algae.Colonic Diseases: Pathological processes in the COLON region of the large intestine (INTESTINE, LARGE).Colonoscopy: Endoscopic examination, therapy or surgery of the luminal surface of the colon.Deglutition Disorders: Difficulty in SWALLOWING which may result from neuromuscular disorder or mechanical obstruction. Dysphagia is classified into two distinct types: oropharyngeal dysphagia due to malfunction of the PHARYNX and UPPER ESOPHAGEAL SPHINCTER; and esophageal dysphagia due to malfunction of the ESOPHAGUS.Contrast Media: Substances used to allow enhanced visualization of tissues.Esophageal Achalasia: A motility disorder of the ESOPHAGUS in which the LOWER ESOPHAGEAL SPHINCTER (near the CARDIA) fails to relax resulting in functional obstruction of the esophagus, and DYSPHAGIA. Achalasia is characterized by a grossly contorted and dilated esophagus (megaesophagus).Barium Radioisotopes: Unstable isotopes of barium that decay or disintegrate emitting radiation. Ba atoms with atomic weights 126-129, 131, 133, and 139-143 are radioactive barium isotopes.Potassium: 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.Fluoroscopy: Production of an image when x-rays strike a fluorescent screen.Hernia, Hiatal: STOMACH herniation located at or near the diaphragmatic opening for the ESOPHAGUS, the esophageal hiatus.Deglutition: The act of taking solids and liquids into the GASTROINTESTINAL TRACT through the mouth and throat.Laminaria: A genus of BROWN ALGAE in the family Laminariaceae. Dried pencil-like pieces may be inserted in the cervix where they swell as they absorb moisture, serving as osmotic dilators.Manometry: Measurement of the pressure or tension of liquids or gases with a manometer.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).Esophagus: The muscular membranous segment between the PHARYNX and the STOMACH in the UPPER GASTROINTESTINAL TRACT.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.Cholecystography: Radiography of the gallbladder after ingestion of a contrast medium.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.Colonography, Computed Tomographic: A non-invasive imaging method that uses computed tomographic data combined with specialized imaging software to examine the colon.Esophageal Diseases: Pathological processes in the ESOPHAGUS.Gastrointestinal Hemorrhage: Bleeding in any segment of the GASTROINTESTINAL TRACT from ESOPHAGUS to RECTUM.Diverticulum, Esophageal: Saccular protrusion beyond the wall of the ESOPHAGUS.Electron Probe Microanalysis: Identification and measurement of ELEMENTS and their location based on the fact that X-RAYS emitted by an element excited by an electron beam have a wavelength characteristic of that element and an intensity related to its concentration. It is performed with an electron microscope fitted with an x-ray spectrometer, in scanning or transmission mode.Intestinal Obstruction: Any impairment, arrest, or reversal of the normal flow of INTESTINAL CONTENTS toward the ANAL CANAL.Diatrizoate Meglumine: A versatile contrast medium used for DIAGNOSTIC X-RAY RADIOLOGY.Occult Blood: Chemical, spectroscopic, or microscopic detection of extremely small amounts of blood.Bisacodyl: A diphenylmethane stimulant laxative used for the treatment of CONSTIPATION and for bowel evacuation. (From Martindale, The Extra Pharmacopoeia, 30th ed, p871)Intussusception: A form of intestinal obstruction caused by the PROLAPSE of a part of the intestine into the adjoining intestinal lumen. There are four types: colic, involving segments of the LARGE INTESTINE; enteric, involving only the SMALL INTESTINE; ileocecal, in which the ILEOCECAL VALVE prolapses into the CECUM, drawing the ILEUM along with it; and ileocolic, in which the ileum prolapses through the ileocecal valve into the COLON.Cesium: A member of the alkali metals. It has an atomic symbol Cs, atomic number 50, and atomic weight 132.91. Cesium has many industrial applications, including the construction of atomic clocks based on its atomic vibrational frequency.Water Wells: Constructions built to access underground water.Cecal Diseases: Pathological developments in the CECUM.Respiratory Aspiration: Inhaling liquid or solids, such as stomach contents, into the RESPIRATORY TRACT. When this causes severe lung damage, it is called ASPIRATION PNEUMONIA.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.Duodenal Diseases: Pathological conditions in the DUODENUM region of the small intestine (INTESTINE, SMALL).Calcium Channels: Voltage-dependent cell membrane glycoproteins selectively permeable to calcium ions. They are categorized as L-, T-, N-, P-, Q-, and R-types based on the activation and inactivation kinetics, ion specificity, and sensitivity to drugs and toxins. The L- and T-types are present throughout the cardiovascular and central nervous systems and the N-, P-, Q-, & R-types are located in neuronal tissue.Colon, Sigmoid: A segment of the COLON between the RECTUM and the descending colon.Diverticulosis, Colonic: A pathological condition characterized by the presence of a number of COLONIC DIVERTICULA in the COLON. Its pathogenesis is multifactorial, including colon aging, motor dysfunction, increases in intraluminal pressure, and lack of dietary fibers.Rectum: The distal segment of the LARGE INTESTINE, between the SIGMOID COLON and the ANAL CANAL.Microradiography: Production of a radiographic image of a small or very thin object on fine-grained photographic film under conditions which permit subsequent microscopic examination or enlargement of the radiograph at linear magnifications of up to several hundred and with a resolution approaching the resolving power of the photographic emulsion (about 1000 lines per millimeter).Megacolon: Dilatation of the COLON, often to alarming dimensions. There are various types of megacolon including congenital megacolon in HIRSCHSPRUNG DISEASE, idiopathic megacolon in CONSTIPATION, and TOXIC MEGACOLON.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.Zeolites: Zeolites. A group of crystalline, hydrated alkali-aluminum silicates. They occur naturally in sedimentary and volcanic rocks, altered basalts, ores, and clay deposits. Some 40 known zeolite minerals and a great number of synthetic zeolites are available commercially. (From Merck Index, 11th ed)Chlorides: Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.Ileal Diseases: Pathological development in the ILEUM including the ILEOCECAL VALVE.Explosive Agents: Substances that are energetically unstable and can produce a sudden expansion of the material, called an explosion, which is accompanied by heat, pressure and noise. Other things which have been described as explosive that are not included here are explosive action of laser heating, human performance, sudden epidemiological outbreaks, or fast cell growth.Gastrointestinal Transit: Passage of food (sometimes in the form of a test meal) through the gastrointestinal tract as measured in minutes or hours. The rate of passage through the intestine is an indicator of small bowel function.Metal Ceramic Alloys: The fusion of ceramics (porcelain) to an alloy of two or more metals for use in restorative and prosthodontic dentistry. Examples of metal alloys employed include cobalt-chromium, gold-palladium, gold-platinum-palladium, and nickel-based alloys.4-Aminopyridine: One of the POTASSIUM CHANNEL BLOCKERS, with secondary effect on calcium currents, which is used mainly as a research tool and to characterize channel subtypes.Cations, Divalent: Positively charged atoms, radicals or groups of atoms with a valence of plus 2, which travel to the cathode or negative pole during electrolysis.Gallopamil: Coronary vasodilator that is an analog of iproveratril (VERAPAMIL) with one more methoxy group on the benzene ring.Melena: The black, tarry, foul-smelling FECES that contain degraded blood.Esophageal Sphincter, Lower: The physiologic or functional barrier to GASTROESOPHAGEAL REFLUX at the esophagogastric junction. Sphincteric muscles remain tonically contracted during the resting state and form the high-pressure zone separating the lumen of the ESOPHAGUS from that of the STOMACH. (Haubrich et al, Bockus Gastroenterology, 5th ed., pp399, 415)Tetraethylammonium: A potassium-selective ion channel blocker. (From J Gen Phys 1994;104(1):173-90)Colonic Polyps: Discrete tissue masses that protrude into the lumen of the COLON. These POLYPS are connected to the wall of the colon either by a stalk, pedunculus, or by a broad base.Radiography, Abdominal: Radiographic visualization of the body between the thorax and the pelvis, i.e., within the peritoneal cavity.Radiography: Examination of any part of the body for diagnostic purposes by means of X-RAYS or GAMMA RAYS, recording the image on a sensitized surface (such as photographic film).Intestinal Polyps: Discrete abnormal tissue masses that protrude into the lumen of the INTESTINE. A polyp is attached to the intestinal wall either by a stalk, pedunculus, or by a broad base.Stomach Volvulus: Twisting of the STOMACH that may result in gastric ISCHEMIA and GASTRIC OUTLET OBSTRUCTION. It is often associated with DIAPHRAGMATIC HERNIA.Electrophysiology: The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.Diverticulum: A pouch or sac developed from a tubular or saccular organ, such as the GASTROINTESTINAL TRACT.Electric Conductivity: The ability of a substrate to allow the passage of ELECTRONS.Tetraethylammonium CompoundsPatch-Clamp Techniques: An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used.Diverticulitis, Colonic: Inflammation of the COLONIC DIVERTICULA, generally with abscess formation and subsequent perforation.Cathartics: Agents that are used to stimulate evacuation of the bowels.Intestinal Fistula: An abnormal anatomical passage between the INTESTINE, and another segment of the intestine or other organs. External intestinal fistula is connected to the SKIN (enterocutaneous fistula). Internal intestinal fistula can be connected to a number of organs, such as STOMACH (gastrocolic fistula), the BILIARY TRACT (cholecystoduodenal fistula), or the URINARY BLADDER of the URINARY TRACT (colovesical fistula). Risk factors include inflammatory processes, cancer, radiation treatment, and surgical misadventures (MEDICAL ERRORS).Duodenal Obstruction: Hindrance of the passage of luminal contents in the DUODENUM. Duodenal obstruction can be partial or complete, and caused by intrinsic or extrinsic factors. Simple obstruction is associated with diminished or stopped flow of luminal contents. Strangulating obstruction is associated with impaired blood flow to the duodenum in addition to obstructed flow of luminal contents.Pneumonia, Aspiration: A type of lung inflammation resulting from the aspiration of food, liquid, or gastric contents into the upper RESPIRATORY TRACT.Calcium Channel Blockers: A class of drugs that act by selective inhibition of calcium influx through cellular membranes.Rana catesbeiana: A species of the family Ranidae (true frogs). The only anuran properly referred to by the common name "bullfrog", it is the largest native anuran in North America.Esophagoscopy: Endoscopic examination, therapy or surgery of the esophagus.Ileocecal Valve: The valve, at the junction of the CECUM with the COLON, that guards the opening where the ILEUM enters the LARGE INTESTINE.Pliability: The quality or state of being able to be bent or creased repeatedly. (From Webster, 3d ed)Fundoplication: Mobilization of the lower end of the esophagus and plication of the fundus of the stomach around it (fundic wrapping) in the treatment of GASTROESOPHAGEAL REFLUX that may be associated with various disorders, such as hiatal hernia. (From Dorland, 28th ed)Cadmium: An element with atomic symbol Cd, atomic number 48, and atomic weight 114. It is a metal and ingestion will lead to CADMIUM POISONING.Endoscopy: Procedures of applying ENDOSCOPES for disease diagnosis and treatment. Endoscopy involves passing an optical instrument through a small incision in the skin i.e., percutaneous; or through a natural orifice and along natural body pathways such as the digestive tract; and/or through an incision in the wall of a tubular structure or organ, i.e. transluminal, to examine or perform surgery on the interior parts of the body.