Alexander J J, Miguel R, Piotrowski J J
Department of Surgery, Case Western Reserve University, Cleveland Metropolitan General Hospital, Ohio 44109, USA.
J Surg Res. 1995 Sep;59(3):371-7. doi: 10.1006/jsre.1995.1178.
Increasing clinical and experimental evidence suggests a multifunctional role of calcium in determining the response of the arterial intima to atherogenic stimuli. In this study, an endothelial cell (EC)-smooth muscle cell (SMC) bilayer model of the arterial wall was used to investigate the effect of calcium manipulation on the sequestration of 125I-labeled LDL within the subendothelial space. Bilayer cell cultures were exposed to EGTA (0.25-2.0 mM), ionophore A23187 (5 x 10(-6) M), lanthanum chloride (0.1 mM), and trifluoperazine (TFP; 0.25 microM). The movement of 125I-labeled LDL (10 micrograms/ml) through the endothelial barrier was measured, as was the binding and cellular uptake of 125I-labeled LDL by each cell type. Extracellular Ca2+ chelation with EGTA and intracellular Ca2+ mobilization with A23187 both increased EC permeability to LDL (P < 0.05; P = 0.0001, respectively), while not significantly affecting EC binding or uptake of lipoprotein. Conversely, these agents increased SMC uptake of LDL (P < 10(-7); P < 10(-8), respectively). Calcium blockade with lanthanum chloride had the opposite effect, reducing EC permeability (P = 0.011) and SMC uptake (P < 10(-5)), while increasing EC uptake (P = 0.016). TFP, a calmodulin inhibitor, had an effect similar to A23187, although reducing SMC uptake of LDL (P = 0.015). Alteration of the calcium gradient across the plasma membrane appears to influence EC permeability. This effect may be stabilized by Ca2+ blockade or calmodulin regulation of cytoplasmic Ca2+. Additional anti-atherogenic effects of calcium blockade may include a reduction in SMC uptake by the SMC.
越来越多的临床和实验证据表明，钙在决定动脉内膜对致动脉粥样硬化刺激的反应中具有多功能作用。在本研究中，使用动脉壁的内皮细胞（EC）-平滑肌细胞（SMC）双层模型来研究钙操作对125I标记的低密度脂蛋白（LDL）在内皮下间隙的摄取的影响。将双层细胞培养物暴露于乙二醇双四乙酸（EGTA，0.25 - 2.0 mM）、离子载体A23187（5×10⁻⁶ M）、氯化镧（0.1 mM）和三氟拉嗪（TFP；0.25 μM）。测量了125I标记的LDL（10 μg/ml）通过内皮屏障的移动，以及每种细胞类型对125I标记的LDL的结合和细胞摄取。用EGTA进行细胞外Ca²⁺螯合以及用A23187进行细胞内Ca²⁺动员均增加了内皮细胞对LDL的通透性（分别为P < 0.05；P = 0.0001），而对内皮细胞结合或摄取脂蛋白没有显著影响。相反，这些试剂增加了平滑肌细胞对LDL的摄取（分别为P < 10⁻⁷；P < 10⁻⁸）。用氯化镧进行钙阻断则产生相反的效果，降低了内皮细胞通透性（P = 0.011）和平滑肌细胞摄取（P < 10⁻⁵），同时增加了内皮细胞摄取（P = 0.016）。钙调蛋白抑制剂TFP具有与A23187相似的作用，尽管降低了平滑肌细胞对LDL的摄取（P = 0.015）。跨质膜钙梯度的改变似乎会影响内皮细胞通透性。这种效应可能通过Ca²⁺阻断或钙调蛋白对细胞质Ca²⁺的调节而稳定下来。钙阻断的其他抗动脉粥样硬化作用可能包括减少平滑肌细胞对LDL的摄取。
