Sévigny J, Grondin G, Gendron F P, Roy J, Beaudoin A R
Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1.
Am J Physiol. 1998 Sep;275(3):G473-82. doi: 10.1152/ajpgi.1998.275.3.G473.
Two isoforms of ATP diphosphohydrolase (ATPDase; EC 3.6.1.5) have been previously characterized, purified, and identified. This enzyme is an ectonucleotidase that catalyzes the sequential release of gamma- and beta-phosphate groups of triphospho- and diphosphonucleosides. One of its putative roles is to modulate the extracellular concentrations of purines in different physiological systems. The purpose of this study was to define, identify, and localize these two isoforms of ATPDase in the pig digestive system. ATPDase activity was measured in pig stomach, duodenum, pancreas, and parotid gland. Enzyme assays, electrophoretograms, and Western blots with a polyclonal antibody that recognizes both isoforms demonstrate the presence of ATPDase in these organs. Immunolocalization showed intense reactions with gastric glands (parietal and chief cells), intestine (columnar epithelial cells), parotid gland, and pancreas. Smooth muscle cells all along the digestive tract were also highly reactive. Considering the variety of purinoceptors associated with the digestive system, the ATPDase is strategically positioned to modulate purine-mediated actions such as electrolyte secretion, glandular secretion, smooth muscle contraction, and blood flow.
先前已对ATP二磷酸水解酶（ATPDase；EC 3.6.1.5）的两种同工型进行了表征、纯化和鉴定。这种酶是一种胞外核苷酸酶，可催化三磷酸和二磷酸核苷的γ-和β-磷酸基团的顺序释放。其假定作用之一是调节不同生理系统中嘌呤的细胞外浓度。本研究的目的是在猪消化系统中定义、鉴定和定位这两种ATPDase同工型。在猪的胃、十二指肠、胰腺和腮腺中测量了ATPDase活性。酶活性测定、电泳图谱以及使用识别这两种同工型的多克隆抗体进行的蛋白质免疫印迹均证明这些器官中存在ATPDase。免疫定位显示胃腺（壁细胞和主细胞）、肠（柱状上皮细胞）、腮腺和胰腺有强烈反应。消化道各处的平滑肌细胞也具有高反应性。考虑到与消化系统相关的多种嘌呤受体，ATPDase在调节嘌呤介导的作用（如电解质分泌、腺体分泌、平滑肌收缩和血流）方面具有重要的战略地位。
