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adenosine (ә-denŽo-sēn) a nucleoside composed of the pentose sugar D-ribose and adenine. It is a structural subunit of RNA (ribonucleic acid). Adenosine nucleotides are involved in the energy metabolism of all cells. Adenosine can be linked to a chain of one, two, or three phosphate groups to form adenosine monophosphate (AMP), adenosine diphosphate (ADP), or adenosine triphosphate (ATP). The bond between the phosphate groups in ADP and the two bonds between phosphate groups in ATP are called high-energy bonds, because hydrolysis of them provides a large amount of free energy that the body can store for later use. Energy derived from the breakdown of carbohydrates, fats, and proteins is used to synthesize ATP; later, energy stored in ATP can be used directly or indirectly to drive the many cellular processes that require energy. a preparation of adenosine that acts as a cardiac depressant of automaticity in the sinus node and of conduction in the atrioventricular node, and sometimes as a vasodilator. It is used as an antiarrhythmic and to cause coronary vasodilation during myocardial perfusion imaging in patients who cannot exercise enough to do an exercise stress test. Administration is intravenous. cyclic adenosine monophosphate
a cyclic nucleotide, adenosine 3′,5′-cyclic monophosphate, involved in the action of many hormones, including catecholamines,
ACTH, and vasopressin. The hormone binds to a specific receptor on the cell membrane of target cells. This activates an enzyme,
adenylate cyclase, which produces cyclic AMP from ATP. Cyclic AMP acts as a second messenger activating other enzymes within
the cell. Abbreviated 3′,5′-AMP, cAMP, and cyclic AMP. adenosine diphosphate(ADP)
a nucleotide, adenosine 5′-pyrophosphate, produced by the hydrolysis of adenosine triphosphate (ATP). It is then converted
back to ATP by the metabolic processes oxidative phosphorylation, glycolysis, and the tricarboxylic acid cycle. adenosine monophosphate(AMP)
a nucleotide, adenosine 5′-phosphate, involved in energy metabolism and nucleotide synthesis. Called also adenylic acid. adenosine triphosphate(ATP)
a nucleotide, adenosine 5′-triphosphate, occurring in all cells, where it stores energy in the form of high-energy phosphate bonds. Free energy is supplied to drive metabolic reactions, to transport molecules against concentration gradients (active transport), and to produce mechanical motion (contraction of myofibrils and microtubules), when ATP is hydrolyzed to ADP and inorganic phosphate or to AMP and inorganic pyrophosphate. ATP is also used to produce high-energy phosphorylated intermediary metabolites, such as glucose 6-phosphate.
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