Abstract：
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.
摘要：
本研究使用多标记免疫荧光研究了大鼠颈动脉体中腺苷5'-二磷酸（ADP）选择性P2Y12嘌呤受体的定位。P2Y12的斑点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-羟化酶免疫反应的化学接受性I型细胞中，但在S100B免疫反应性神经胶质样II型细胞中没有。P2Y12免疫反应性位于包含VNUT免疫反应性I型细胞的细胞簇中，这些细胞被核周细胞质和II型细胞的细胞质过程所包围，这些细胞对核苷三磷酸二磷酸水解酶2（NTPDase2）和NTPDase3具有免疫反应性，可水解胞外核苷酸三和/或二磷酸。在使用颈动脉体的ATP生物发光测定中，在选择性NTPDases抑制剂ARL67156存在下,细胞外ATP的降解减弱,提示组织中NTPDases的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NTPDases降解为ADP和腺苷5'-单磷酸，ADP通过P2Y12嘌呤受体调节I型细胞。
