Gleeson R A, Carr W E, Trapido-Rosenthal H G
Whitney Laboratory, University of Florida, St. Augustine 32086.
Brain Res. 1989 Sep 11;497(1):12-20. doi: 10.1016/0006-8993(89)90964-5.
As measured by extracellular single-cell recording, the responses to adenosine triphosphate (ATP) by ATP-sensitive chemoreceptors (ATP cells) on the olfactory organ of the spiny lobster are markedly suppressed by adenosine diphosphate (ADP), adenosine monophosphate (AMP) and to a lesser extent, adenosine, when each is presented in binary mixture with ATP. In the presence of ADP, the dose-response function for ATP exhibits an apparent parallel displacement to the right suggesting that this antagonism may occur via competition at the ATP receptor. Structure-activity relationships reveal that the structural requirements for antagonism by diphosphate analogs of ADP bear little relationship to the requirements for the agonistic activity of corresponding triphosphate analogs. Under Mg2+-free conditions, the desensitization of ATP cells tends to be delayed resulting in enhanced responses to ATP. Desensitization does not appear to be related to the generation of the antagonist, ADP, from ATP via ecto-ATPase activity. The results of this study suggest that the responses of ATP cells to the ATP contained in natural stimulus (odor) mixtures can be tempered by the suppressive interactions of other nucleotides in the mixtures. Furthermore, these interactions may be mitigated and/or intensified by the actions of sensillar ectonucleotidases.
通过细胞外单细胞记录测量发现，当二磷酸腺苷（ADP）、一磷酸腺苷（AMP）以及程度稍轻的腺苷分别与三磷酸腺苷（ATP）以二元混合物形式呈现时，多刺龙虾嗅觉器官上的ATP敏感化学感受器（ATP细胞）对ATP的反应会受到显著抑制。在存在ADP的情况下，ATP的剂量反应函数表现出明显的向右平行位移，这表明这种拮抗作用可能是通过在ATP受体上的竞争发生的。构效关系表明，ADP二磷酸类似物的拮抗结构要求与相应三磷酸类似物的激动活性要求几乎没有关系。在无镁离子条件下，ATP细胞的脱敏往往会延迟，导致对ATP的反应增强。脱敏似乎与通过胞外ATP酶活性从ATP产生拮抗剂ADP无关。这项研究的结果表明，ATP细胞对天然刺激（气味）混合物中所含ATP的反应可能会受到混合物中其他核苷酸抑制性相互作用的调节。此外，这些相互作用可能会因感觉器胞外核苷酸酶的作用而减轻和/或增强。
