Sobey C G, Brooks R M, Heistad D D
Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242-1081, USA.
Circ Res. 1995 Sep;77(3):536-43. doi: 10.1161/01.res.77.3.536.
Atherosclerotic lesions contain monocytes/macrophages and vascular smooth muscle cells and thus may have an increased capacity for generation of nitric oxide by inducible nitric oxide synthase (NOS). We used three approaches (contractile responses, generation of L-citrulline from L-arginine, and staining with NADPH-diaphorase) to test the hypothesis that after administration of lipopolysaccharide (LPS) in vivo, generation of nitric oxide by inducible NOS is augmented in atherosclerotic arteries. New Zealand White (normal, n = 18) and Watanabe heritable hyperlipidemic (atherosclerotic, n = 21) rabbits were anesthetized and injected intravenously with vehicle or LPS. Contractile responsiveness of aortic segments was examined in vitro 4 hours after injection of LPS in vivo. There was a substantial (approximately fivefold) decrease in contractile sensitivity of aortas from LPS-treated atherosclerotic rabbits and a small (approximately twofold) decrease in normal rabbits. Incubation of aortic segments with aminoguanidine, which inhibits inducible NOS, restored contractile responsiveness after LPS treatment. In vitro assay of conversion of [14C]L-arginine to [14C]L-citrulline by aortic segments demonstrated marked (approximately fivefold) increase in calcium-independent conversion of [14C]L-arginine by LPS-treated atherosclerotic, but not normal, aortas. NADPH-diaphorase staining demonstrated positive cells only in the endothelium of normal rabbits and in the lesions and media of the atherosclerotic aortas in both vehicle- and LPS-treated rabbits. The general distribution of these NADPH-diaphorase-positive cells resembled that of smooth muscle cells and not macrophages. Thus, impairment of contractile responses, generation of L-citrulline, and staining with NADPH-diaphorase suggest that atherosclerotic arteries have increased capacity for generation of nitric oxide by inducible NOS.
动脉粥样硬化病变包含单核细胞/巨噬细胞和血管平滑肌细胞，因此可能通过诱导型一氧化氮合酶（NOS）产生一氧化氮的能力增强。我们采用了三种方法（收缩反应、L-精氨酸生成L-瓜氨酸以及用NADPH-黄递酶染色）来检验这一假设，即在体内给予脂多糖（LPS）后，诱导型NOS在动脉粥样硬化动脉中产生一氧化氮的能力会增强。将新西兰白兔（正常，n = 18）和渡边遗传性高脂血症兔（动脉粥样硬化，n = 21）麻醉，并静脉注射溶媒或LPS。在体内注射LPS 4小时后，体外检测主动脉段的收缩反应性。经LPS处理的动脉粥样硬化兔的主动脉收缩敏感性大幅降低（约五倍），正常兔则小幅降低（约两倍）。用抑制诱导型NOS的氨基胍孵育主动脉段可恢复LPS处理后的收缩反应性。主动脉段将[14C]L-精氨酸转化为[14C]L-瓜氨酸的体外实验表明，经LPS处理的动脉粥样硬化主动脉（而非正常主动脉）对[14C]L-精氨酸的非钙依赖性转化显著增加（约五倍）。NADPH-黄递酶染色显示，正常兔仅在内皮中有阳性细胞，而在溶媒和LPS处理的兔的动脉粥样硬化主动脉的病变及中膜中均有阳性细胞。这些NADPH-黄递酶阳性细胞的总体分布与平滑肌细胞相似，而非巨噬细胞。因此，收缩反应受损、L-瓜氨酸生成以及NADPH-黄递酶染色表明，动脉粥样硬化动脉通过诱导型NOS产生一氧化氮的能力增强。
