Tsujino M, Hirata Y, Imai T, Kanno K, Eguchi S, Ito H, Marumo F
Second Department of Internal Medicine, Tokyo Medical and Dental University, Japan.
Circulation. 1994 Jul;90(1):375-83. doi: 10.1161/01.cir.90.1.375.
Impaired myocardial contractility in septic shock is protracting, which may be caused by cytokine-induced nitric oxide (NO) synthesis in the heart. However, the cellular mechanism by which cytokines induce nitric oxide synthase (NOS) in cardiocytes remains obscure.
We studied the effect of human recombinant interleukin-1 beta (IL-1 beta) on synthesis of NO2-/NO3- (NOx) and the expression of NOS mRNA and protein in cultured neonatal rat cardiocytes. IL-1 beta dose-dependently (0.1 to 10 ng/mL) stimulated NOx production as a function of time (6 to 48 hours). Northern blot analysis using complementary DNAs for rat brain-type constitutive (c) NOS and mouse macrophage-type inducible (i) NOS as probes showed that IL-1 beta induced expression of mRNA for iNOS but not for cNOS, starting after 6 hours and reaching a maximum after 48 hours in cardiocytes. IL-1 beta similarly induced iNOS mRNA expression in cultured adult rat cardiocytes in a time-dependent manner. Western blot analysis using specific antibody against the N-terminal fragment of mouse iNOS revealed the expression of 130-kD iNOS-like protein in IL-1 beta-treated cardiocytes. Northern blotting and immunocytochemical study revealed that IL-1 beta-induced iNOS mRNA and iNOS-like immunoreactivity were exclusively localized to cardiac myocytes but also to nonmyocytes, to a lesser extent. NG-mono-methyl-L-arginine, an NOS inhibitor, completely blocked the IL-1 beta-induced NOx production, whose effect was reversed by L-arginine but not by D-arginine. Dexamethasone inhibited the IL-1 beta-induced NOx production as well as iNOS mRNA expression. Cycloheximide and actinomycin D completely inhibited the IL-1 beta-induced NOx production and iNOS mRNA expression. Neither a calmodulin inhibitor (W-7), a protein kinase C inhibitor (calphostin C), nor a Ca2+ channel antagonist (nicardipine) showed any effect on the IL-1 beta-induced NOx production.
These data demonstrate that IL-1 beta induces macrophage-type iNOS mRNA expression mainly by cardiac myocytes but also by nonmyocytes to a lesser extent, and subsequent de novo protein synthesis of iNOS leads to excessive local production of NO by cardiocytes.
脓毒性休克时心肌收缩力受损持续存在，这可能是由细胞因子诱导心脏产生一氧化氮（NO）所致。然而，细胞因子诱导心肌细胞中一氧化氮合酶（NOS）的细胞机制仍不清楚。
我们研究了重组人白细胞介素-1β（IL-1β）对培养的新生大鼠心肌细胞中NO2⁻/NO3⁻（NOx）合成以及NOS mRNA和蛋白表达的影响。IL-1β以剂量依赖方式（0.1至10 ng/mL）刺激NOx产生，且呈时间依赖性（6至48小时）。用大鼠脑型组成型（c）NOS和小鼠巨噬细胞型诱导型（i）NOS的互补DNA作为探针进行Northern印迹分析显示，IL-1β诱导心肌细胞中iNOS的mRNA表达，但不诱导cNOS的mRNA表达，6小时后开始诱导，48小时达到最大值。IL-1β同样以时间依赖方式诱导培养的成年大鼠心肌细胞中iNOS mRNA表达。用针对小鼠iNOS N端片段的特异性抗体进行Western印迹分析显示，在经IL-治疗的心肌细胞中有130-kD的iNOS样蛋白表达。Northern印迹和免疫细胞化学研究显示，IL-1β诱导的iNOS mRNA和iNOS样免疫反应性不仅局限于心肌细胞，在非心肌细胞中也有表达，但程度较轻。NOS抑制剂NG-单甲基-L-精氨酸完全阻断了IL-1β诱导的NOx产生，L-精氨酸可逆转其作用，而D-精氨酸则不能。地塞米松抑制IL-1β诱导的NOx产生以及iNOS mRNA表达。放线菌酮和放线菌素D完全抑制IL-1β诱导的NOx产生和iNOS mRNA表达。钙调蛋白抑制剂（W-7）、蛋白激酶C抑制剂（钙泊三醇C）和Ca²⁺通道拮抗剂（尼卡地平）对IL-1β诱导的NOx产生均无影响。
这些数据表明，IL-1β主要通过心肌细胞，但也在较小程度上通过非心肌细胞诱导巨噬细胞型iNOS mRNA表达，随后iNOS的从头蛋白合成导致心肌细胞局部过量产生NO。
