James N L, Harrison D G, Nerem R M
Department of Internal Medicine, Emory University School of Medicine, Atlanta Veterans Administration Medical Center, Georgia, USA.
FASEB J. 1995 Jul;9(10):968-73. doi: 10.1096/fasebj.9.10.7615166.
The purpose of this study was to characterize the effect of various shear conditions on endothelial cell intracellular calcium ([Ca2+]i). Bovine aortic endothelial cells (BAEC) were loaded with Fluo-3 and exposed to flow in a parallel plate flow chamber designed for confocal microscopy. The flow medium was medium 199 (M-199), which was prepared with and without adenosine triphosphate (ATP). In the presence of ATP, initiation of flow at a shear stress of 2.5 dyn/cm2 evoked a strong, sustained elevation of [Ca2+]i that gradually returned to baseline levels over 10 to 15 min. By contrast, in the absence of ATP, initiation of flow at 2.5 dyn/cm2 produced only transient increases in [Ca2+]i in a small proportion of the cells. As shear rate was increased from 2.5 to 15 dyn/cm2 in this medium, both the relative fluorescence of the monolayer and the proportion of cells across the monolayer that displayed calcium transients increased in a dose-dependent fashion. In conclusion, the response of an endothelial cell monolayer to increasing levels of shear is not only to increase [Ca2+]i within individual cells, but to increase the duration of response and the number of cells responding at the onset of shear. This recruitment of larger numbers of cells at higher levels of shear may represent a novel signaling mechanism within the endothelium.
本研究的目的是描述各种剪切条件对内皮细胞胞内钙（[Ca2+]i）的影响。用Fluo-3标记牛主动脉内皮细胞（BAEC），并将其置于专为共聚焦显微镜设计的平行板流动腔中使其暴露于流动状态。流动介质为199培养基（M-199），分别在添加和不添加三磷酸腺苷（ATP）的情况下配制。在ATP存在时，以2.5达因/平方厘米的剪切应力开始流动会引起[Ca2+]i强烈、持续升高，并在10至15分钟内逐渐恢复到基线水平。相比之下，在无ATP时，以2.5达因/平方厘米开始流动仅在一小部分细胞中产生[Ca2+]i的短暂增加。当在此培养基中剪切速率从2.5增加到15达因/平方厘米时，单层细胞的相对荧光以及整个单层中显示钙瞬变的细胞比例均呈剂量依赖性增加。总之，内皮细胞单层对剪切力水平增加的反应不仅是增加单个细胞内的[Ca2+]i，而且是增加反应持续时间以及在剪切开始时做出反应的细胞数量。在较高剪切力水平下更多细胞的这种募集可能代表内皮内一种新的信号传导机制。
