Cyclic adenosine monophosphate (cAMP, cyclic AMP or 3'-5'-cyclic adenosine monophosphate) is a molecule that is important in many biological processes; it is derived from adenosine triphosphate (ATP) by adenylate cyclase located on the inner side of the plasma membrane and anchored at various locations in the interior of the cell. Around 1960 Earl W. Sutherland, Jr. showed that cyclic adenosine monophosphate (cAMP) serves as the secondary messenger within the cell. Cyclic AMP works by activating protein kinase A (PKA, or cAMP-dependent protein kinase). PKA is normally inactive as a tetrameric holoenzyme, consisting of two catalytic and two regulatory units with the regulatory units blocking the catalytic centers of the catalytic units. Cyclic AMP binds to specific locations on the regulatory units of the protein kinase, and causes dissociation between the regulatory and catalytic subunits, thus enabling those catalytic units to phosphorylate substrate proteins. It was discovered, that melanocytes require the RAS/RAF/MEK/ERK and the cyclic AMP (cAMP) signaling pathways to maintain the fine balance between proliferation and differentiation. cAMP suppressed CRAF activity in melanocytes and that was essential to suppress the oncogenic potential of CRAF in the cells. When RAS was mutated in melanoma, the cells switched their signaling from BRAF to CRAF. That switch was accompanied by dysregulated cAMP signaling, a step that was necessary to allow CRAF to signal to MEK. Thus, a fundamental switch in RAF isoform usage occurs when RAS was mutated in melanoma, and that occurs in the context of disrupted cAMP signaling. These data have important implications for the development of therapeutic strategies to treat this life-threatening disease.

Adenosine triphosphate (ATP) is an adenine nucleotide containing three phosphate groups esterified to the sugar moiety. Adenosine triphosphate is the energy source in living cells. In physiological conditions, the average concentration varies from 3150 mM in mammalian cells to 1500–1900 mM in human blood cells. Extracellular adenosine and adenosine triphosphate (ATP) are involved in biological processes including neurotransmission, muscle contraction, cardiac function, platelet function, vasodilatation, signal transduction and secretion in a variety of cell types. A large family of membrane-bound receptors mediates cell signalling by ATP and adenosine. These purinergic receptors ultimately determine the variety of effects induced by extracellular ATP and adenosine. ATP and adenosine have strong negative chronotropic and dromotropic effects on the mammalian heart. The sensitivity of the sinus node and the atrioventricular node to ATP and adenosine manifests pronounced variability among species. For more than three decades, ATP has been used routinely in Europe in the acute therapy of paroxysmal supraventricular tachycardia. ATPace™, an injectable formulation of adenosine 5′-triphosphate (ATP), was developed by Cordex Pharma, Inc. (Cordex) as a diagnostic and therapeutic drug for the management of cardiac bradyarrhythmias. Extracellular ATP exerts multiple effects in various cell types by activating cell-surface receptors known as P2 receptors. In the heart, ATP suppresses the automaticity of cardiac pacemakers and atrioventricular (AV) nodal conduction via adenosine, the product of its degradation by ecto-enzymes, as well as by triggering a cardio-cardiac vagal reflex. ATP, given as a rapid intravenous bolus injection, has been used since the late 1940s as a highly effective and safe therapeutic agent for the acute termination of reentrant paroxysmal supraventricular tachycardia (PSVT) involving the AV node. In addition, preliminary studies have shown that ATP can also be used as a diagnostic agent for the identification of several cardiac disorders including sinus node dysfunction (sick sinus syndrome), dual AV nodal pathways, long QT syndrome, and bradycardic syncope. The US Food and Drug Administration has approved Cordex formulation for ATP as an Investigational New Drug and two pathways for its marketing approval; one therapeutic, i.e., acute termination of paroxysmal PSVT, and the other diagnostic, i.e., the identification of patients with bradycardic syncope who can benefit from pacemaker therapy. However later ATPace development for the treatment of bradycardia and paroxysmal supraventricular tachycardia was discontinued.

Adenosine is a nucleoside that is composed of adenine and d-ribose, occurring in all cells of the body and play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter. Adenocard (adenosine injection) is used as an initial treatment for the termination of paroxysmal supraventricular tachycardia (PVST), including that associated with accessory bypass tracts (Wolff-Parkinson-White Syndrome). When clinically advisable, appropriate vagal maneuvers. Adenocard does not convert atrial flutter, atrial fibrillation, or ventricular tachycardia to normal sinus rhythm. In the presence of atrial flutter or atrial fibrillation, a transient modest slowing of ventricular response may occur immediately following Adenocard administration. Adenosine slows conduction time through the A-V node, can interrupt the reentry pathways through the A-V node, and can restore normal sinus rhythm. This effect may be mediated through the drug's activation of cell-surface A1 and A2 adenosine receptors. Adenocard is antagonized competitively by methylxanthines such as caffeine and theophylline, and potentiated by blockers of nucleoside transport such as dipyridamole. Adenocard is not blocked by atropine. Adenosine also inhibits the slow inward calcium current and activation of adenylate cyclase in smooth muscle cells, thereby causing relaxation of vascular smooth muscle. By increasing blood flow in normal coronary arteries with little or no increase in stenotic arteries, adenosine produces a relative difference in thallous (thallium) chloride TI 201 uptake in myocardium supplied by normal verus stenotic coronary arteries.

Adenosine monophosphate (AMP) is a nucleotide, consisting of a phosphate group, the sugar ribose, and the nucleobase adenine. AMP is an activator of several enzymes in the tissues. In the glycolytic pathway, the enzyme phosphofructokinase is inhibited by ATP but the inhibition is reversed by AMP, the deciding factor for the reaction being the ratio between ATP and AMP. In medicine, AMP is used mainly as an alternative to adenosine for treatment of ischemia and as a tool compound to measure hyperresponsiveness of airways.