An organ chamber, organ bath, or isolated tissue bath is a chamber in which isolated organs or tissues can be administered with drugs, or stimulated electrically, in order to measure their function. The tissue in the organ bath is typically oxygenated with carbogen and kept in a solution such as Tyrode's solution or lactated Ringer's solution.[ citation needed ] Historically, they have also been called gut baths. [1]
It is used in pharmacology research, particularly when studying the contraction of smooth muscle in tissues such as ileum, [2] colon, [3] vas deferens, [4] trachea, [5] bladder, [6] corpus cavernosum, [7] and blood vessels such as aortic rings. The contraction of smooth muscle tissues can be readily measured with a myograph; this type of physiological response is more readily quantifiable than that of other tissues. Organ baths were originally developed to study the effects of agonists and antagonists on excitable tissues, such as nervous tissue and muscle though they have been adapted to study tissues such as epithelium. [8] Typical tissues and receptors studied with organ bath preparations include nicotinic, muscarinic, and histamine receptors in the ileum or beta adrenoceptors in the bladder. [8] Tissues are typically taken from rodents, such as guinea pigs, mice, and rats.
For studying the effects of drugs on receptors in drug discovery and combinatorial chemistry, novel techniques such as high throughput screening, ultrahigh throughput screening and high content screening, pharmacogenomics, proteomics, and array technology have largely superseded the use of organ baths. [9] These techniques can allow more receptor specificity than organ bath preparations, as a single tissue sample can express many different receptor types.[ citation needed ]
The use of organ bath preparations for the measurement of physiological tissue responses to drug concentrations allows the generation of dose response curves. This in turn allows the quantification of a drug's pharmacological profile in the tissue in question, such as the calculation of the drug's EC50, IC50, and Hill coefficient.[ citation needed ]
Examples of important contributions made using this technique include:
Pharmacology is a branch of medicine, biology and pharmaceutical sciences concerned with drug or medication action, where a drug may be defined as any artificial, natural, or endogenous molecule which exerts a biochemical or physiological effect on the cell, tissue, organ, or organism. More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal or abnormal biochemical function. If substances have medicinal properties, they are considered pharmaceuticals.
Acetylcholine (ACh) is an organic chemical that functions in the brain and body of many types of animals as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Parts in the body that use or are affected by acetylcholine are referred to as cholinergic. Substances that increase or decrease the overall activity of the cholinergic system are called cholinergics and anticholinergics, respectively.
The adrenergic receptors or adrenoceptors are a class of G protein-coupled receptors that are targets of many catecholamines like norepinephrine (noradrenaline) and epinephrine (adrenaline) produced by the body, but also many medications like beta blockers, beta-2 (β2) agonists and alpha-2 (α2) agonists, which are used to treat high blood pressure and asthma, for example.
The vas deferens, or ductus deferens, is part of the male reproductive system of many vertebrates. The ducts transport sperm from the epididymis to the ejaculatory ducts in anticipation of ejaculation. The vas deferens is a partially coiled tube which exits the abdominal cavity through the inguinal canal.
A neuroeffector junction is a site where a motor neuron releases a neurotransmitter to affect a target—non-neuronal—cell. This junction functions like a synapse. However, unlike most neurons, somatic efferent motor neurons innervate skeletal muscle, and are always excitatory. Visceral efferent neurons innervate smooth muscle, cardiac muscle, and glands, and have the ability to be either excitatory or inhibitory in function. Neuroeffector junctions are known as neuromuscular junctions when the target cell is a muscle fiber.
Muscarinic acetylcholine receptors, or mAChRs, are acetylcholine receptors that form G protein-coupled receptor complexes in the cell membranes of certain neurons and other cells. They play several roles, including acting as the main end-receptor stimulated by acetylcholine released from postganglionic fibers in the parasympathetic nervous system.
Agmatine, also known as (4-aminobutyl)guanidine, is an aminoguanidine that was discovered in 1910 by Albrecht Kossel. Agmatine is a chemical substance which is naturally created from the amino acid arginine. Agmatine has been shown to exert modulatory action at multiple molecular targets, notably: neurotransmitter systems, ion channels, nitric oxide (NO) synthesis and polyamine metabolism and this provides bases for further research into potential applications.
Orphenadrine is an anticholinergic drug of the ethanolamine antihistamine class; it is closely related to diphenhydramine. It is used to treat muscle pain and to help with motor control in Parkinson's disease, but has largely been superseded by newer drugs. This substance is considered a dirty drug due to its multiple mechanism of action in different pathways. It was discovered and developed in the 1940s.
H2 receptors are positively coupled to adenylate cyclase via Gs. It is a potent stimulant of cAMP production, which leads to activation of protein kinase A. PKA functions to phosphorylate certain proteins, affecting their activity. The drug betazole is an example of a histamine H2 receptor agonist.
Hans Walter Kosterlitz FRS was a German-born British biochemist.
Norepinephrine (NE), also called noradrenaline (NA) or noradrenalin, is an organic chemical in the catecholamine family that functions in the brain and body as both a hormone and neurotransmitter. The name "noradrenaline," derived from Latin roots meaning "at/alongside the kidneys," is more commonly used in the United Kingdom; in the United States, "norepinephrine," derived from Greek roots having that same meaning, is usually preferred. "Norepinephrine" is also the international nonproprietary name given to the drug. Regardless of which name is used for the substance itself, parts of the body that produce or are affected by it are referred to as noradrenergic.
A muscarinic receptor antagonist (MRA) is a type of anticholinergic agent that blocks the activity of the muscarinic acetylcholine receptor. The muscarinic receptor is a protein involved in the transmission of signals through certain parts of the nervous system, and muscarinic receptor antagonists work to prevent this transmission from occurring. Notably, muscarinic antagonists reduce the activation of the parasympathetic nervous system. The normal function of the parasympathetic system is often summarised as "rest-and-digest", and includes slowing of the heart, an increased rate of digestion, narrowing of the airways, promotion of urination, and sexual arousal. Muscarinic antagonists counter this parasympathetic "rest-and-digest" response, and also work elsewhere in both the central and peripheral nervous systems.
NESS-0327 is a drug used in scientific research which acts as an extremely potent and selective antagonist of the cannabinoid receptor CB1. It is much more potent an antagonist, and more selective for the CB1 receptor over CB2, than the more commonly used ligand rimonabant, with a Ki at CB1 of 350fM (i.e. 0.00035nM) and a selectivity of over 60,000x for CB1 over CB2. Independently, two other groups have described only modest nanomolar CB1 affinity for this compound (125nM and 18.4nM). Also unlike rimonabant, NESS-0327 does not appear to act as an inverse agonist at higher doses, instead being a purely neutral antagonist which blocks the CB1 receptor but does not produce any physiological effect of its own.
Urapidil is a sympatholytic antihypertensive drug. It acts as an α1-adrenoceptor antagonist and as an 5-HT1A receptor agonist. Although an initial report suggested that urapidil was also an α2-adrenoceptor agonist, this was not substantiated in later studies that demonstrated it was devoid of agonist actions in the dog saphenous vein and the guinea-pig ileum. Unlike some other α1-adrenoceptor antagonists, urapidil does not elicit reflex tachycardia, and this may be related to its weak β1-adrenoceptor antagonist activity, as well as its effect on cardiac vagal drive. Urapidil is currently not approved by the U.S. Food and Drug Administration, but it is available in Europe.
RDS-127 is a drug which is used in scientific research. It acts as a D2-like receptor agonist and also has some serotonin and adrenergic agonist effects, as well as some anticholinergic action, and produces both anorectic and pro-sexual effects in animal studies.
Candocuronium iodide is an aminosteroid neuromuscular-blocking drug or skeletal muscle relaxant in the category of non-depolarizing neuromuscular-blocking drugs. Its potential adjunctive use in anesthesia to facilitate endotracheal intubation and to provide skeletal muscle relaxation during surgery or mechanical ventilation was briefly evaluated in clinical studies in India, but further development discontinued because of attendant cardiovascular effects, primarily tachycardia that was no worse than but also not an improvement over the clinically established pancuronium bromide. Candocuronium demonstrated a short duration and a rapid onset of action, with little or no ganglion blocking activity, and it was only slightly less potent than pancuronium.
Eptazocine (Sedapain) is an opioid analgesic which was introduced in Japan by Morishita in 1987. It acts as a mixed κ-opioid receptor agonist and μ-opioid receptor antagonist.
The catecholamines comprise the endogenous substances dopamine, noradrenaline (norepinephrine), and adrenaline (epinephrine) as well as numerous artificially synthesized compounds such as isoprenaline. Their investigation comprises a major chapter in the history of physiology, biochemistry, and pharmacology. Adrenaline was the first hormone extracted from an endocrine gland and obtained in pure form, before the word hormone was coined. It was also the first hormone whose structure and biosynthesis were clarified. Apart from acetylcholine, adrenaline and noradrenaline were the first neurotransmitters to be discovered and the first intercellular biochemical signals to be found in intracellular vesicles. The β-adrenoceptor was the first G protein-coupled receptor, the gene of which was cloned. Goal-directed catecholamine research began with the preparation by George Oliver and Edward Albert Sharpey-Schafer of a pharmacologically active extract from the adrenal glands.
John Hughes is a British neuroscientist who shared the 1978 Albert Lasker Award for Basic Medical Research for the discovery of met-enkephalin and leu-enkephalin. This discovery demonstrated that opiate drugs exert their effects on the human brain by mimicking endogenous neurotransmitters, the opioid peptides.
Autonomic drugs can either inhibit or enhance the functions of the parasympathetic and sympathetic nervous systems. This type of drug can be used to treat a wide range of diseases, such as glaucoma, asthma, urinary, gastrointestinal and cardiopulmonary disorders.