Department of Cell Physiology, Nagoya City University Graduate School of Medical Sciences, Mizuho-ku, Nagoya, Japan; Japan Society for the Promotion of Science, Chiyoda-ku, Tokyo, Japan.
Neurogastroenterol Motil. 2014 Jan;26(1):115-23. doi: 10.1111/nmo.12240. Epub 2013 Oct 8.
In the subserosal layer between the longitudinal muscle layer and mesothelium, heterogeneous populations of interstitial cells are distributed. As the distribution of nerve elements in this layer is sparse as compared with the nerve plexus layer or tunica muscularis, there may be unique communication among subserosal interstitial cells (SSICs). This study aimed to explore functional properties of SSICs.
In subserosal preparations of the guinea-pig proximal colon, changes in intracellular Ca(2+) ([Ca(2+) ]i ) were visualized using Fluo-4 Ca(2+) imaging. Immunohistochemistry was also performed to identify the SSICs exhibiting Ca(2+) transients.
A majority of SSICs responded to adenosine triphosphate (ATP, 10 μM) by increasing [Ca(2+) ]i , but remained quiescent during the application of acetylcholine (10 μM). ATP-induced Ca(2+) responses were mimicked by adenosine 5'-diphosphate (10 μM), MRS2365 (10 nM) but not α, β-methylene ATP (10 μM) or uridine triphosphate (10 μM), and could be reproduced in Ca(2+) -free solution, suggesting that ATP acts via P2Y receptors, most likely P2Y1 subtype, but not P2X receptors. Live staining of the same preparations after Ca(2+) imaging indicated the ATP-sensitive SSICs were not positive for c-Kit antibody, a specific marker for gastrointestinal interstitial cells of Cajal (ICC). Immunohistochemistry identified vimentin (mesenchymal cell marker)+/Kit- and SK3 (fibroblast-like cell (FLC) marker)+/Kit- cells that had a similar morphology to the ATP-sensitive SSICs in Ca(2+) imaging.
CONCLUSIONS & INFERENCES: A majority of the SSICs in the guinea-pig proximal colon, presumably FLC, are capable of responding to ATP and thus may contribute to smooth muscle relaxation upon stimulation with ATP released from non-neuronal cells.
在纵肌层和间皮之间的黏膜下层中，分布着异质的间质细胞群体。由于与神经丛层或肌层相比，该层中的神经元素分布较为稀疏，因此黏膜下层间质细胞（SSIC）之间可能存在独特的通讯。本研究旨在探讨 SSIC 的功能特性。
在豚鼠近端结肠的黏膜下层制剂中，使用 Fluo-4 Ca（2+）成像观察细胞内 Ca（2+）（[Ca（2+）]i）的变化。还进行了免疫组织化学染色以鉴定表现出 Ca（2+）瞬变的 SSIC。
大多数 SSIC 对三磷酸腺苷（ATP，10 μM）的反应是通过增加[Ca（2+）]i 来实现的，但在乙酰胆碱（10 μM）的应用过程中保持静止。ATP 诱导的 Ca（2+）反应可被二磷酸腺苷（10 μM）、MRS2365（10 nM）模拟，但不能被α、β-亚甲基 ATP（10 μM）或三磷酸尿苷（10 μM）模拟，并且在无 Ca（2+）溶液中可以重现，这表明 ATP 通过 P2Y 受体起作用，最有可能是 P2Y1 亚型，但不是 P2X 受体。在 Ca（2+）成像后对同一制剂进行活染色表明，ATP 敏感的 SSIC 对胃肠道间质细胞 Cajal（ICC）的特异性标志物 c-Kit 抗体呈阴性。免疫组织化学鉴定出波形蛋白（间充质细胞标志物）+/Kit-和 SK3（成纤维样细胞（FLC）标志物）+/Kit-细胞，它们在 Ca（2+）成像中具有与 ATP 敏感的 SSIC 相似的形态。
豚鼠近端结肠的大多数 SSIC，推测为 FLC，能够对 ATP 作出反应，因此可能有助于非神经元细胞释放的 ATP 刺激平滑肌松弛。
