Narenjkar J, Marsh S J, Assem E S
Department of Pharmacology, University College London, UK.
Cell Calcium. 1999 Dec;26(6):261-9. doi: 10.1054/ceca.1999.0065.
Using the ratiometric Ca2+ indicator, indo-1, the antigen-induced increase in intracellular Ca2+ concentration ([Ca2+]i) was measured in individual RBL-2H3 cells which had been passively sensitized with monoclonal antibody to the dintrophenyl (DNP) haptenic group. Antigenic stimulation using DNP-human serum albumin conjugate (DNP-HSA) induced concentration-dependent asynchronous Ca2+ oscillations, or irregular spikes. To achieve a quantitative comparison of the effects of different concentrations of antigen on changes in Ca2+[i, the area under the curve (AUC) of Ca2+ oscillations in each cell was calculated. The dose-response curve of the calculated AUC is consistent with the bell-shaped dose-response curve for antigen-induced mediator release, depolarization and 86Rb(+)-efflux. Ca2+ oscillations induced by antigenic stimulation were abolished by removal of external Ca2+ and the subsequent reintroduction of external Ca2+ caused their resumption. To investigate the role of Ca2+ oscillations in the secretory response, changes in [Ca2+]i induced by concanavalin A (Con-A), A23187, thapsigargin and NECA were also monitored. Con-A mimicked the response induced by antigen, whilst A23187 and thapsigargin induced a large transient non-oscillatory response. NECA, an adenosine receptor agonist, induced only a small transient rise in Ca2+[i without oscillatory behaviour. Since all these stimuli accept NECA-induced degranulation in these cells, it is suggested that, although Ca2+ oscillations are not essential for the initiation of secretion, they probably underlie the in-vivo physiological response of mast cells and basophils to an antigenic challenge. They also seem to enhance the efficacy of the Ca2+ signal.
使用比率型钙离子指示剂indo-1，在已用抗二硝基苯基（DNP）半抗原基团的单克隆抗体被动致敏的单个RBL-2H3细胞中测量抗原诱导的细胞内钙离子浓度（[Ca2+]i）升高。用DNP-人血清白蛋白偶联物（DNP-HSA）进行抗原刺激可诱导浓度依赖性异步钙离子振荡或不规则尖峰。为了定量比较不同浓度抗原对Ca2+[i变化的影响，计算了每个细胞中钙离子振荡的曲线下面积（AUC）。计算得到的AUC的剂量反应曲线与抗原诱导的介质释放、去极化和86Rb(+)-外流的钟形剂量反应曲线一致。去除细胞外钙离子可消除抗原刺激诱导的钙离子振荡，随后重新引入细胞外钙离子可使其恢复。为了研究钙离子振荡在分泌反应中的作用，还监测了伴刀豆球蛋白A（Con-A）、A23187、毒胡萝卜素和NECA诱导的[Ca2+]i变化。Con-A模拟了抗原诱导的反应，而A23187和毒胡萝卜素诱导了大的瞬时非振荡反应。NECA，一种腺苷受体激动剂，仅诱导Ca2+[i的小瞬时升高，无振荡行为。由于所有这些刺激都能使这些细胞发生NECA诱导的脱颗粒，因此表明，虽然钙离子振荡对于分泌的起始不是必需的，但它们可能是肥大细胞和嗜碱性粒细胞对抗原刺激的体内生理反应的基础。它们似乎也增强了钙离子信号的效力。
