Involvement of ATP released from non-neuronal tlssues in presynaptic neuromodulation.

1992年至1993年在我的研究项目（04670132）中所获得的结果如下：抑制剂对非神经组织ATP释放的外核苷酸酶代谢的影响用荧光素酶-荧光素酶法测定了外源性ATP在有和无输精管和回肠纵肌的洗浴液中的降解。在含有悬浮组织的培养基中，浴液中ATP的量以时间依赖性的方式在15分钟后迅速下降至零。ATP的衰减曲线几乎不受胞外ATP酶抑制剂如FSBA和DFDNB以及胞外-5 '-核苷酸酶抑制剂α，β-亚甲基ADP的影响。此外，分别在去甲肾上腺素和氨甲酰胆碱存在下，输精管和回肠段释放ATP的衰减曲线，除DFDNB外，其他胞外酶的抑制剂均无明显作用，DFDNB似乎能抑制这些组织分泌素引起的ATP释放。 ...更多信息 本实验观察了P_（2*）受体激动剂α，β-mATP（α，β-mATP）对电刺激豚鼠回肠纵肌引起的内源性乙酰胆碱（ACh）释放的影响。用HPLC-ECD系统测定ACh的释放。α，β-mATP（30 μ M）可抑制电诱发的ACh释放，而P_1受体拮抗剂茶碱（100 μ M）则不能抑制这种作用。ATP类似物以一种对P_2受体拮抗剂苏拉明敏感而对Ca^2+和阿托品不敏感的方式诱导平滑肌释放ATP，提示P_2受体介导的平滑肌ATP释放。结果表明，α，β-mATP并不通过直接刺激突触前P_1受体而减少ATP的释放，而是由ATP类似物在突触后释放的内源性ATP在突触糖中被代谢为腺苷，而腺苷触发了P_1嘌呤受体敏感的胆碱能传递的神经调节。少

The results obtained in my research project (04670132) during 1992 to 1993 are summarized as follows.Effects of inhibitors on metabolism by ectonucleotidases of ATP release from non-neuronal tissuesDegradation of exogenously applied ATP in the bathing solution with and without vas deferens and ileal longitudinal muscles of guinea pigs were measured by luciferin-luciferase assay. In medium with a suspended tissue, the amount of ATP in the bathing solution decreased quickly in a time-dependent manner to zero after 15 min. The decay curves of ATP were virtually unaffected by inhibitors of ecto-ATPase such as FSBA and DFDNB and by an ecto-5'-nucleotidase inhibitor, alpha, beta-methylene ADP.In addition, decay curves of ATP released from vas deferens and ileal segment in the presence of noradrenaline and bethanechol, respectively, were unchanged by inhibitors of these ectoenzymes except DFDNB.DFDNB seems to inhibit the release of ATP evoked by the secretagogues from these tissues.Cholinergi … More c neuromodulation evoked by ATP released from a non-neuronal tissueEffects of alpha, beta-methylene ATP (alpha, beta-mATP,a P_<2*>-receptor agonist) on endogenous ACh release evoked by electrical nerve stimulation were evaluated in guinea pig ileal longitudinal muscles. Release of ACh was measured with an HPLC-ECD system. Electrically evoked ACh release was reduced by alpha, beta-mATP at concentrations of 3 ad 30 muM.The reduction by alpha, beta-mATP (30 muM) was not observed in the presence of theophylline (100 muM), a P_1-receptor antagonist. The ATP analog induced the release of ATP in a suramin (P_2-receptor antagonist) -sensitive but Ca^<2+>-and atropine-insensitive manner, suggesting P_2-receptor-mediated release of ATP from the smooth muscle. We conclude from these findings that alpha, beta-mATP dose not reduce ATP release by direct stimulation of presynaptic P_1-receptors, and that endogenous ATP released postjunctionally by the ATP analog is decomposed metabolically to adenosine in the synaose and this adenosine triggers P_1-purinoceptor-sensitive neuromodulation of cholinergic transmission. Less