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Adenosine (symbol A) is an ... When given to dilate the arteries, such as in a "stress test", the dosage is typically 0.14 mg/kg/min, administered for 4 or 6 minutes ...
Caffeine keeps you awake by blocking adenosine receptors. Each type of adenosine receptor has different functions, although with some overlap. [3] For instance, both A 1 receptors and A 2A play roles in the heart, regulating myocardial oxygen consumption and coronary blood flow, while the A 2A receptor also has broader anti-inflammatory effects throughout the body. [4]
Overall, adenosine decreases the heart’s rate and force of contraction, which increases blood supply to the cardiac muscle. Given specific circumstances this mechanism (which is intended to protect the heart) may cause atropine-resistant refractory bradyasystole. [3] Adenosine's effects are concentration-dependent.
Caffeine is usually held 24 hours prior to an adenosine stress test, as it is a competitive antagonist of the A2A adenosine receptor and can attenuate the vasodilatory effects adenosine. [citation needed] Aminophylline may be used to attenuate severe and/or persistent adverse reactions to adenosine and regadenoson. [39]
Cyclic adenosine monophosphate (cAMP)-mediated opening of HCN and KCNQ channels is inhibited, which enhances prefrontal cortical synaptic connectivity and neuronal firing. [43] [44] In monkeys, guanfacine improves working memory, attention regulation, and behavioral inhibition, and these actions are independent of its sedative effects. [18]
Adenosine is a neuromodulator that is responsible for motor function, mood, memory, and learning. Its main purpose is the coordination of responses to different neurotransmitters. [5] Adenosine plays many important roles in biological systems, for example in the central nervous-, cardiovascular-, hepatic-, renal- and respiratory system.
Adenosine deaminase (also known as adenosine aminohydrolase, or ADA) is an enzyme (EC 3.5.4.4) involved in purine metabolism. It is needed for the breakdown of adenosine from food and for the turnover of nucleic acids in tissues. Its primary function in humans is the development and maintenance of the immune system. [5]
Adenosine diphosphate ... The approved clinical dosage of ticagrelor is a 180-mg loading dose PO and a 90-mg a day maintenance dose. [32]