The present study investigated the localization of the adenosine 5′-diphosphate (ADP)-selective P2Y12 purinoceptors in the rat carotid body using multilabeling immunofluorescence. Punctate immunoreactive products for P2Y12 were distributed in chemoreceptive type I cells immunoreactive to vesicular nucleotide transporter (VNUT) or dopamine beta-hydroxylase, but not in S100B-immunoreactive glial-like type II cells. P2Y12 immunoreactivity was localized in cell clusters containing VNUT-immunoreactive type I cells surrounded by the perinuclear cytoplasm and cytoplasmic processes of type II cells immunoreactive for ectonucleoside triphosphate diphosphohydrolase 2 (NTPDase2) and NTPDase3, which hydrolyze extracellular nucleotide tri- and/or di-phosphates. In ATP bioluminescence assays using carotid bodies, the degradation of extracellular ATP was attenuated in the presence of the selective NTPDases inhibitor ARL67156, suggesting ATP-degrading activity by NTPDases in the tissue. These results suggest that ATP released from type I cells is degraded into ADP and adenosine 5′-monophosphate by NTPDases expressed in type II cells, and that ADP modulates type I cells via P2Y12 purinoceptors.

中文翻译：

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大鼠颈动脉体中 P2Y12 嘌呤受体的免疫组织化学定位

本研究利用多标记免疫荧光技术研究了大鼠颈动脉体中 5'-二磷酸腺苷 (ADP) 选择性 P2Y12 嘌呤受体的定位。P2Y12 的点状免疫反应产物分布在对囊泡核苷酸转运蛋白 (VNUT) 或多巴胺 β-羟化酶有免疫反应的化学感受性 I 型细胞中，但不在 S100B 免疫反应性神经胶质样 II 型细胞中。P2Y12 免疫反应性位于含有 VNUT 免疫反应性 I 型细胞的细胞簇中，周围有 II 型细胞的核周细胞质和细胞质突起，对外核苷三磷酸二磷酸水解酶 2 (NTPDase2) 和 NTPDase3 具有免疫反应，可水解细胞外核苷酸三磷酸和/或二磷酸。在使用颈动脉体的 ATP 生物发光测定中，在选择性 NTPDase 抑制剂 ARL67156 存在的情况下，细胞外 ATP 的降解减弱，表明组织中 NTPDase 具有 ATP 降解活性。这些结果表明，I型细胞释放的ATP被II型细胞中表达的NTPD酶降解为ADP和5'-单磷酸腺苷，并且ADP通过P2Y12嘌呤受体调节I型细胞。