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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]
The A 1 receptors couple to G i/o and decrease cAMP levels, while the A 2 adenosine receptors couple to G s, which stimulates adenylate cyclase activity. In addition, A 1 receptors couple to G o , which has been reported to mediate adenosine inhibition of Ca 2+ conductance, whereas A 2B and A 3 receptors also couple to G q and stimulate ...
It involves the activation of purinergic receptors in the cell and/or in nearby cells, thereby regulating cellular functions. [ 1 ] It was proposed after Adenosine triphosphate (ATP) was identified in 1970 as the transmitter responsible for non-adrenergic, noncholinergic neurotransmission .
The actions of the A 2A receptor are complicated by the fact that a variety of functional heteromers composed of a mixture of A 2A subunits with subunits from other unrelated G-protein coupled receptors have been found in the brain, adding a further degree of complexity to the role of adenosine in modulation of neuronal activity.
Fatigue and sedation after heavy exertion can be caused by excess adenosine in the cells which signals muscle fiber to feel fatigued. In the brain, excess adenosine decreases alertness and causes sleepiness. In this way, adenosine may play a role in fatigue from MADD. [4] Recovery from over-exertion can be hours, days or even months.
Adenosine triphosphate (ATP) is a nucleoside triphosphate [2] that provides energy to drive and support many processes in living cells, such as muscle contraction, nerve impulse propagation, and chemical synthesis. Found in all known forms of life, it is often referred to as the "molecular unit of currency" for intracellular energy transfer. [3]
A 1 receptors are implicated in sleep promotion by inhibiting wake-promoting cholinergic neurons in the basal forebrain. [6] A 1 receptors are also present in smooth muscle throughout the vascular system. [7] The adenosine A 1 receptor has been found to be ubiquitous throughout the entire body. [citation needed]
P1 receptors are preferentially activated by adenosine and P2Y receptors are preferentially more activated by ATP. P1 and P2Y receptors are known to be widely distributed in the brain, heart, kidneys, and adipose tissue. Xanthines (e.g. caffeine) specifically block adenosine receptors, and are known to induce a stimulating effect to one's behavior.