Qiu H Y, Bernard C, Matrougui K, Tedgui A, Levy B I
Institut National de la Santé et de la Recherche Médicale, Université Paris VII, France.
J Vasc Res. 1996 Sep-Oct;33(5):370-9. doi: 10.1159/000159165.
This study was designed to evaluate the effects of lipopolysaccharide (LPS)-activated macrophages in the perfused mesenteric circulation of the rat. The mesenteric network of anesthetized rats was perfused in situ under constant flow conditions and the diameter and pressure of the mesenteric artery were continuously recorded. For the first 30 min the mesenteric network was perfused with an RPMI solution (control condition); thereafter it was perfused for 60 min with the same solution containing either (1) LPS (1 microgram/ml), (2) elicited macrophages (10(6) cells/ml), (3) LPS-activated macrophages or (4) supernatants derived from LPS-activated macrophages (SPN). The changes in arterial diameter induced by topical application of phenylephrine (PE, 10 mumol/l) were measured under control conditions and then 30 and 60 min after the onset of perfusions. The intravascular pressure was similarly increased (51 +/- 6%, p < 0.001) by the perfusion of activated macrophages or elicited macrophages but was not affected by perfusion of LPS or SPN. Despite the same level of transmural mesenteric pressure in rats perfused with activated and elicited macrophages, the mesenteric diameter was significantly larger with activated than with elicited macrophages (p < 0.05). Under control conditions, PE induced a marked decrease in arterial diameter from 495 +/- 15 to 265 +/- 13 microns (p < 0.001). Perfusion of LPS, elicited macrophages or SPN did not modify the vascular reactivity to PE. Perfusion of activated macrophages reduced the PE-induced contraction by 77 +/- 6% (p < 0.001). Perfusion of elicited macrophages with a nitric oxide (NO) donor (SIN-1, 10 mumol/l) reproduced the effect of LPS-activated macrophages while addition of an NO scavenger (oxyhemoglobin, 10 mumol/l) prevented the depression of the vascular reactivity to PE by activated macrophages. Finally, activated macrophages preincubated with an inhibitor of NO synthesis (NG-monomethyl-L-arginine); L-NMMA), and then perfused in RPMI solution without L-NMMA had no effect on the PE reactivity of the mesenteric artery suggesting that NO released by activated macrophages directly and rapidly inhibited the contractility of the mesenteric artery. The results of this study demonstrate the opposing effects of macrophages in the mesenteric circulation to increase microvascular resistance by a rheological effect while decreasing the reactivity of the mesenteric artery as a result of NO released by macrophages.
本研究旨在评估脂多糖（LPS）激活的巨噬细胞对大鼠肠系膜灌注循环的影响。在恒流条件下对麻醉大鼠的肠系膜网络进行原位灌注，并持续记录肠系膜动脉的直径和压力。在最初的30分钟内，用RPMI溶液灌注肠系膜网络（对照条件）；此后，用含有以下成分的相同溶液灌注60分钟：（1）LPS（1微克/毫升）、（2）诱导巨噬细胞（10⁶个细胞/毫升）、（3）LPS激活的巨噬细胞或（4）LPS激活的巨噬细胞衍生的上清液（SPN）。在对照条件下以及灌注开始后30分钟和60分钟时，测量局部应用去氧肾上腺素（PE，10微摩尔/升）引起的动脉直径变化。灌注激活的巨噬细胞或诱导巨噬细胞同样使血管内压力升高（51±6%，p<0.001），但LPS或SPN灌注对此无影响。尽管灌注激活的巨噬细胞和诱导巨噬细胞的大鼠跨壁肠系膜压力水平相同，但激活巨噬细胞组的肠系膜直径显著大于诱导巨噬细胞组（p<0.05）。在对照条件下，PE使动脉直径从495±15微米显著减小至265±13微米（p<0.001）。灌注LPS、诱导巨噬细胞或SPN并未改变血管对PE的反应性。灌注激活的巨噬细胞使PE诱导的收缩减少77±6%（p<0.001）。用一氧化氮（NO）供体（SIN-1，10微摩尔/升）灌注诱导巨噬细胞可重现LPS激活的巨噬细胞的作用，而添加NO清除剂（氧合血红蛋白，10微摩尔/升）可防止激活的巨噬细胞降低血管对PE的反应性。最后，用NO合成抑制剂（NG-单甲基-L-精氨酸；L-NMMA）预孵育激活的巨噬细胞，然后在不含L-NMMA的RPMI溶液中灌注，对肠系膜动脉的PE反应性无影响，这表明激活的巨噬细胞释放的NO直接且迅速地抑制了肠系膜动脉的收缩性。本研究结果表明，巨噬细胞在肠系膜循环中具有相反的作用，即通过流变学效应增加微血管阻力，同时由于巨噬细胞释放的NO降低肠系膜动脉的反应性。
