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H 2 receptors are a type of histamine receptor found in many parts of the anatomy of humans and other animals. They are positively coupled to adenylate cyclase via G s alpha subunit . It is a potent stimulant of cAMP production, which leads to activation of protein kinase A . [ 5 ]
H2 antagonists (H2 blockers) are used to reduce stomach acid production and treat conditions like gastroesophageal reflux disease (GERD) and peptic ulcers. [ 3 ] H 3 receptor H3 Receptors: These receptors are predominantly located in the central nervous system (CNS), particularly in regions associated with neurotransmitter release and modulation.
Cimetidine was the prototypical histamine H 2 receptor antagonist from which later drugs were developed. Cimetidine was the culmination of a project at Smith, Kline & French (SK&F; now GlaxoSmithKline) by James W. Black, C. Robin Ganellin, and others to develop a histamine receptor antagonist that would suppress stomach acid secretion.
A histamine agonist is a drug which causes increased activity at one or more of the four histamine receptor subtypes. H 1 agonists promote wakefulness. [1] H 2: Betazole and Impromidine are examples of agonists used in diagnostics to increase histamine. H 3: Betahistine is a weak Histamine 1 agonist and a very strong antagonist of the Histamine ...
There are also different subtypes of receptor which elicit different effects in response to the same agonist. For example, there are two types of histamine receptor: H1 and H2. Activation of the H1 subtype receptor causes contraction of smooth muscle, whereas activation of the H2 receptor stimulates gastric secretion.
Agonist muscles are also called prime movers since they produce most of the force, and control of an action. [6] Agonists cause a movement to occur through their own activation. [7] For example, the triceps brachii contracts, producing a shortening (concentric) contraction, during the up phase of a push-up (elbow extension).
Histamine H 2 receptor • CNS: Dorsal striatum (caudate nucleus and putamen), cerebral cortex (external layers), hippocampal formation, dentate nucleus of the cerebellum • Periphery: Located on parietal cells, vascular smooth muscle cells, neutrophils, mast cells, as well as on cells in the heart and uterus
Physiological antagonism describes the behavior of a substance that produces effects counteracting those of another substance (a result similar to that produced by an antagonist blocking the action of an agonist at the same receptor) using a mechanism that does not involve binding to the same receptor.