Gardner J D, Benoit J N
Department of Physiology, University of South Alabama, Mobile, AL 36688USA.
J Biomed Sci. 2000 Jul-Aug;7(4):304-10. doi: 10.1007/BF02253249.
The purpose of this study was to evaluate the contribution of capacitative calcium influx to intracellular calcium levels during agonist-induced stimulation of vascular smooth muscle cells.
Aortic vascular smooth muscle cells (A7r5) were loaded with Indo-1 and intracellular calcium transients were measured. Cells were challenged with either arginine vasopressin (0. 5 microM) or thapsigargin (1 microM). Lanthanum (1 mM) was used to block capacitative calcium influx through store-operated channels. Calcium traces were analyzed for basal, peak and plateau responses. Recordings were derivatized and integrated to gain additional information. Nonlinear regression provided a time constant that describes restoration of ionic equilibrium involving both sequestration and extrusion pathways.
Stimulation of cells with thapsigargin produced a non-L-type calcium influx that was attenuated by lanthanum. Cells excited with vasopressin exhibited a rapid calcium increase followed by a gradual decrease to a plateau level. Lanthanum pretreatment prior to stimulation caused no significant change in baseline, peak or plateau calcium levels as compared to control. Lanthanum caused no significant change in maximal calcium release rate, calcium integrals or time constant as compared to control.
Capacitative calcium entry can occur in vascular smooth muscle cells, but does not appear to contribute significantly to the vasopressin response.
本研究旨在评估在激动剂诱导刺激血管平滑肌细胞过程中，容量性钙内流对细胞内钙水平的作用。
用Indo-1加载主动脉血管平滑肌细胞（A7r5）并测量细胞内钙瞬变。用精氨酸加压素（0.5微摩尔）或毒胡萝卜素（1微摩尔）刺激细胞。用镧（1毫摩尔）阻断通过储存-操纵性通道的容量性钙内流。分析钙信号记录的基础、峰值和平台期反应。对记录进行求导和积分以获取更多信息。非线性回归提供了一个时间常数，该常数描述了涉及螯合和外排途径的离子平衡恢复情况。
用毒胡萝卜素刺激细胞产生了一种非L型钙内流，该内流被镧减弱。用加压素刺激的细胞表现出钙快速增加，随后逐渐下降至平台期水平。与对照组相比，刺激前用镧预处理对基线、峰值或平台期钙水平无显著影响。与对照组相比，镧对最大钙释放速率、钙积分或时间常数无显著影响。
容量性钙内流可发生在血管平滑肌细胞中，但似乎对加压素反应没有显著贡献。
