Li S, Fan S X, McKenna T M
Septic Shock Research Program, Naval Medical Research Institute, Bethesda, Maryland 20889-5607, USA.
Am J Physiol. 1997 Jan;272(1 Pt 2):H576-84. doi: 10.1152/ajpheart.1997.272.1.H576.
Treatment of vascular tissue with low levels of lipopolysaccharide (LPS) induces nitric oxide synthase (NOS) activity and diminishes vascular contractility. However, in cultured vascular smooth muscle cells (VSMC), very high doses of LPS or the combination of LPS with cytokines are required for the induction of nitric oxide (NO) formation. The aims of this study were to establish a cell model to investigate LPS-induced hypocontractility and NO production and to test the hypothesis that responses of VSMC to LPS are differentiation regulated. We used Matrigel basement membrane matrix to maintain VSMC differentiation and found that VSMC cultured on Matrigel retained significant contractility in response to KCl stimulation. Incubation of VSMC with low levels of LPS(1-100 ng/ml) induced NOS mRNA and protein, induced NO production, and decreased cell contractility in a time- and dose-dependent fashion. The NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME) partially restored LPS-treated VSMC contractility, whereas L-arginine reversed the contractility-restoring effect of L-NAME. These results suggest that VSMC grown on Matrigel are a useful experimental model for investigations into signal transduction mechanisms responsible for LPS-induced vascular hypocontractility.
用低水平脂多糖（LPS）处理血管组织可诱导一氧化氮合酶（NOS）活性并降低血管收缩性。然而，在培养的血管平滑肌细胞（VSMC）中，需要非常高剂量的LPS或LPS与细胞因子的组合才能诱导一氧化氮（NO）生成。本研究的目的是建立一个细胞模型来研究LPS诱导的收缩性降低和NO产生，并检验VSMC对LPS的反应受分化调节这一假设。我们使用基质胶基底膜基质来维持VSMC分化，发现培养在基质胶上的VSMC对KCl刺激仍保留显著的收缩性。用低水平LPS（1 - 100 ng/ml）孵育VSMC可诱导NOS mRNA和蛋白表达，诱导NO产生，并以时间和剂量依赖的方式降低细胞收缩性。NOS抑制剂NG-硝基-L-精氨酸甲酯（L-NAME）部分恢复了LPS处理的VSMC的收缩性，而L-精氨酸逆转了L-NAME的收缩性恢复作用。这些结果表明，培养在基质胶上的VSMC是研究负责LPS诱导的血管收缩性降低的信号转导机制的有用实验模型。
