Fraile M L, López de Pablo A L, Marco E J, Sanz L, Moreno M J, Conde M V
Departamento de Fisiología, Facultad de Medicina, Universidad Autónoma, Madrid, Spain.
Rev Esp Fisiol. 1993 Sep;49(3):187-93.
The possible contribution of nitric oxide (NO) to the endothelium-dependent relaxation of isolated cat cerebral arteries was studied by examining the effects of the L-arginine (L-ARG) analogues L-canavanine and NG-nitro-L-arginine (L-NOARG) on acetylcholine-induced relaxation. L-canavanine (100 microM) as well as L-NOARG (10 microM) decreased significantly the relaxant response of acetylcholine, their effect being significantly reversed by L-arginine (10 microM) but not by D-arginine (10 microM). In resting conditions, L-NOARG (10 microM) elicited a contraction of 314 +/- 42 mg in arteries endowed with endothelium that was significantly diminished by endothelium removal to 88 +/- 35 mg, and by (10 microM) L-arginine to 135 +/- 54 mg. L-canavanine (100 microM) induced contractions in arteries with and without endothelial cells which were not statistically different. The results suggest that the endothelium of cat cerebral arteries has the ability to synthesize nitric oxide from L-arginine and to release it, even in the absence of a stimulus such as that of acetylcholine. L-NOARG seems to be a specific and powerful inhibitor of nitric oxide synthesis.
通过检测L-精氨酸（L-ARG）类似物L-刀豆氨酸和N-硝基-L-精氨酸（L-NOARG）对乙酰胆碱诱导的舒张作用，研究了一氧化氮（NO）对离体猫脑动脉内皮依赖性舒张的可能作用。L-刀豆氨酸（100微摩尔）以及L-NOARG（10微摩尔）显著降低了乙酰胆碱的舒张反应，L-精氨酸（10微摩尔）可显著逆转它们的作用，而D-精氨酸（10微摩尔）则不能。在静息状态下，L-NOARG（10微摩尔）使有内皮的动脉产生314±42毫克的收缩，去除内皮后收缩显著减弱至88±35毫克，加入（10微摩尔）L-精氨酸后减弱至135±54毫克。L-刀豆氨酸（100微摩尔）在有和没有内皮细胞层动脉中均诱导收缩，二者无统计学差异。结果表明，猫脑动脉内皮具有从L-精氨酸合成一氧化氮并释放的能力，即使在没有乙酰胆碱这类刺激的情况下也是如此。L-NOARG似乎是一氧化氮合成的一种特异性强效抑制剂。
