Kiemer A K, Vollmar A M
Institute of Pharmacology, Toxicology and Pharmacy, University of Munich, Germany.
Endocrinology. 1997 Oct;138(10):4282-90. doi: 10.1210/endo.138.10.5459.
Atrial natriuretic peptide (ANP) has previously been suggested to inhibit the production of NO in LPS-activated primary macrophages. The aim of the present study was 1) to examine whether ANP elicits this effect also on macrophage cell lines (RAW 264.7, J774), 2) to elucidate whether ANP is the only natriuretic peptide (NP) inhibiting NO synthesis, 3) to look for the expression of natriuretic peptide receptors (NPR) on macrophages, 4) to consequently determine the type of receptor mediating the ANP effect and 5) to obtain first information on the underlying mechanism. Whereas ANP dose dependently (10(-6)-10(-8) M) inhibited NO synthesis (measured as nitrite accumulation, 20h) in all four types of macrophages (bone marrow derived and peritoneal macrophages; RAW 264.7 and J 774), urodilatin and atriopeptin I displayed only a weak effect restricted to the highest concentration (10(-6) M) employed. Importantly, C-type natriuretic peptide (CNP) showed no NO-inhibitory effect. The lack of effect of CNP was shown not to be due to its lower stability or its missing receptor. Macrophages were shown to express all three natriuretic peptide receptors (NPR-A, NPR-B, NPR-C) using RT-PCR technique. Furthermore, two types of NPR-B seem to be present in macrophages. The effect of ANP was mediated via the guanylate cyclase coupled NPR-A as shown by experiments employing stable cGMP analogs, the NPR-A antagonist HS-142-1, LY-83583, a cGMP inhibitor as well as C-ANF, a specific ligand of the NPR-C. Reduction of nitrite accumulation by ANP was highest when added simultaneously with LPS and abolished when added 12 h after LPS stimulation. In summary, ANP was shown to inhibit NO production of LPS-activated macrophages via cGMP.
此前有研究表明，心房利钠肽（ANP）可抑制脂多糖激活的原代巨噬细胞中一氧化氮（NO）的产生。本研究的目的是：1）检测ANP对巨噬细胞系（RAW 264.7、J774）是否也有此作用；2）阐明ANP是否是唯一抑制NO合成的利钠肽（NP）；3）寻找巨噬细胞上利钠肽受体（NPR）的表达情况；4）进而确定介导ANP作用的受体类型；5）获取有关潜在机制的初步信息。结果显示，ANP在所有四种类型的巨噬细胞（骨髓来源的巨噬细胞和腹腔巨噬细胞；RAW 264.7和J774）中均呈剂量依赖性（10⁻⁶ - 10⁻⁸ M）抑制NO合成（以亚硝酸盐积累量衡量，20小时），而尿钠素和心钠素I仅在所用最高浓度（10⁻⁶ M）时表现出微弱作用。重要的是，C型利钠肽（CNP）未显示出NO抑制作用。研究表明，CNP缺乏作用并非因其稳定性较低或缺乏受体。利用逆转录聚合酶链反应（RT-PCR）技术显示，巨噬细胞表达所有三种利钠肽受体（NPR-A、NPR-B、NPR-C）。此外，巨噬细胞中似乎存在两种类型的NPR-B。采用稳定的环鸟苷酸（cGMP）类似物、NPR-A拮抗剂HS-142-1、cGMP抑制剂LY-83583以及NPR-C的特异性配体C-ANF进行的实验表明，ANP的作用是通过与鸟苷酸环化酶偶联的NPR-A介导的。当与脂多糖同时添加时，ANP对亚硝酸盐积累的减少作用最大，而在脂多糖刺激12小时后添加则作用消失。总之，研究表明ANP通过cGMP抑制脂多糖激活的巨噬细胞产生NO。
