ADENOSINE RECEPTOR AGONISTS AND ANTAGONISTS

腺苷通过以下途径调节广泛的生理功能 与至少两种主要的腺苷受体相互作用。这个 A1类腺苷受体对腺苷环化酶有抑制作用，而 A2类分子对腺苷环化酶有刺激作用。腺苷亚类 受体也会发生。其中一些对钙通道有抑制作用， 有些对钾通道有刺激作用，有些则激活鸟苷。 环化酶，有的调节磷脂，有的翻转，有的造成光滑 通过一种不明确的机制来放松肌肉。A的活动 2-取代腺苷的范围导致了模型的发展 A2a-腺苷受体的结合部位。这包括一种疏水的 与腺嘌呤环的2位位置分开的区域 侧向容忍度小。A2a受体的亲和力相关性很好 作为血管扩张剂。抑制或刺激的多肽 在亚马逊水母的分泌物中发现了激动剂的结合 青蛙。刺激性多肽腺调节蛋白具有以下序列 GLWSKIKEVGKEAAKAAAKAAGKAALGAVSEAV。很可能有一个或多个D- 氨基酸残基存在。NIH品系男性的慢性咖啡因 小白鼠的运动探索性活动减少。这个 咖啡因刺激运动活动的阈值降低为 是腺苷类似物抑制作用的阈值。这个 尼古丁的抑郁作用被消除，而毒碱的作用被取消 激动剂奥曲莫林略有降低。因此，慢性咖啡因 似乎显著改变了中枢腺苷的功能 胆碱能通路。

Adenosine regulates a wide range of physiological functions through interaction with at least two major classes of adenosine receptors. The A1 class of adenosine receptors is inhibitory to adenylate cyclase, while the A2 class is stimulatory to adenylate cyclase. Subclasses of adenosine receptors also occur. Some of these are inhibitory to calcium channels, some are stimulatory to potassium channels, some activate guanylate cyclase, some modulate phospholipid, turn over and some cause smooth muscle relaxation through a poorly defined mechanism. Activities of a range of 2-substituted adenosines led to development of model for the binding site on A2A-adenosine receptors. This consisted of a hydrophobic site separated from the 2-position of the adenine ring by a region with little lateral tolerance. Affinities at A2A-receptors correlated well with potencies as vasodilators. Peptides inhibitory or stimulatory to binding of agonists were discovered in secretions from an Amazonian hylid frog. The stimulatory peptide adenoregulin had the following sequence GLWSKIKEVGKEAAKAAAKAAGKAALGAVSEAV. It appears likely that one or more D- amino acid residues are present. Chronic caffeine in NIH strain male white mice results in a reduction in locomotor exploratory activity. The threshold for stimulation of locomotor activity to caffeine is lowered as are the thresholds for depressant effects of adenosine analogs. The depressant effects of nicotine are abolished, while those of a muscarinic agonist, oxotremorine are slightly reduced. Thus, chronic caffeine appears to significantly alter function of central adenosine and cholinergic pathways.