Sneddon P, Westfall D P, Fedan J S
Eur J Pharmacol. 1982 May 7;80(1):93-8. doi: 10.1016/0014-2999(82)90181-9.
When tone was raised by histamine (10(-6) M), field stimulation (0.2-8 Hz) induced relaxation of the rabbit anococcygeus muscle in the continuous presence of guanethidine (10(-5) M) and atropine (10(-6) M). Similar relaxations could be induced by ATP and adenosine, which were approximately equipotent, but the non-hydrolyzable analogue beta-gamma-methylene ATP was less potent and produced relaxations which were slower. Although PGE2 was a potent relaxant in this muscle, release of endogenous prostaglandins does not appear to mediate the response to ATP since indomethacin (2 x 10(-5) M) pretreatment did not reduce responses to ATP. The specific ATP receptor antagonist, ANAPP3 (10(-4) or 10(-3) M) did not reduce responses to nerve stimulation and only slightly reduced those of exogenous ATP. The results indicate that responses to ATP could be mediated partly by the products of its hydrolysis and do not support the proposal that ATP is the inhibitory transmitter in this muscle.
当用组胺（10⁻⁶ M）提高肌张力时，在胍乙啶（10⁻⁵ M）和阿托品（10⁻⁶ M）持续存在的情况下，场刺激（0.2 - 8 Hz）可诱导兔肛门尾骨肌舒张。ATP和腺苷也可诱导类似的舒张，它们的效力大致相当，但不可水解的类似物β - γ - 亚甲基ATP效力较弱且产生的舒张较慢。尽管PGE2是该肌肉中的强效舒张剂，但内源性前列腺素的释放似乎并不介导对ATP的反应，因为吲哚美辛（2×10⁻⁵ M）预处理并未降低对ATP的反应。特异性ATP受体拮抗剂ANAPP3（10⁻⁴或10⁻³ M）并未降低对神经刺激的反应，仅略微降低了对外源性ATP的反应。结果表明，对ATP的反应可能部分由其水解产物介导，并不支持ATP是该肌肉中抑制性递质的观点。
