Jamieson D, Davis P
Eur J Pharmacol. 1980 Oct 17;67(2-3):295-300. doi: 10.1016/0014-2999(80)90511-7.
1-Methylisoguanosine, a novel purine isolated from the sponge Tedania digitata (Schmidt) selectively inhibited contractions produced by nerve stimulation in the guinea-pig ileum but was without effect on contractions produced by acetylcholine or histamine. The ED50 for inhibition of nicotine responses or responses to submaximal transmural stimulation was 1.1 mumoles/l. The inhibition of nerve-mediated contractions appeared to be due to inhibition of transmitter release from nerve endings in the ileum, as has been suggested for the action of adenosine. Theophylline antagonized the action of 1-methylisoguanosine and overall the results suggest that 1-methyl-isoguanosine acts at an adenosine receptor in the guinea-pig ileum, but is approximately ten times more potent than adenosine itself. A series of related purines which were resistant to the action of adenosine deaminase were also tested for their effect on the nerve-mediated contractions of guinea-pig ileum and the results compared with the in vivo effect on muscle relaxation in mice. All active purines tested produced results qualitatively similar to those of 1-methylisoguanosine itself.
1-甲基异鸟苷是从海绵指状特氏海绵（施密特）中分离出的一种新型嘌呤，它能选择性抑制豚鼠回肠神经刺激所产生的收缩，但对乙酰胆碱或组胺所产生的收缩没有影响。抑制尼古丁反应或次最大跨壁刺激反应的半数有效剂量（ED50）为1.1微摩尔/升。神经介导的收缩受到抑制似乎是由于抑制了回肠神经末梢递质的释放，就像腺苷的作用所表明的那样。茶碱拮抗1-甲基异鸟苷的作用，总体结果表明1-甲基异鸟苷作用于豚鼠回肠的腺苷受体，但效力约为腺苷本身的十倍。还测试了一系列对腺苷脱氨酶作用有抗性的相关嘌呤对豚鼠回肠神经介导收缩的影响，并将结果与它们对小鼠肌肉松弛的体内作用进行了比较。所有测试的活性嘌呤产生的结果在质量上与1-甲基异鸟苷本身相似。
