Bourreau J P, Kitchener P, Kwan C Y, Daniel E E
Department of Biomedical Sciences, McMaster University, Hamilton, Canada.
Biol Signals. 1992 Nov-Dec;1(6):322-30. doi: 10.1159/000109337.
Using a recognized inhibitor of nitric oxide (NO) synthesis, Nw-nitro L-arginine methyl ester (L-NAME), we tested the hypothesis of the existence of a nonendothelial source of NO in vascular tissue using rings of rat thoracic aorta in which endothelial cells have been removed by mechanical abrasion and have totally lost their endothelium-dependent relaxation. Contractility of the muscle was tested by recording the concentration-dependent contraction of the preparations induced by an alpha-adrenergic agonist, phenylephrine. Contractility in aortas from Wistar-Kyoto normotensive rats (WKY) and spontaneous hypertensive rats (SHR) was not significantly affected by a 30-min to 2-hour incubation with L-NAME prior to agonist stimulation. However, preparations incubated for 30 min with 1 mM L-arginine (L-ARG) and then washed for 1 h in standard Krebs solution had a significantly reduced contraction to phenylephrine in both WKY and SHR. In these preparations pretreated with L-ARG, L-NAME significantly increased contractility in both WKY and SHR; this effect was prevented by L-ARG but not by D-arginine. Responses to phenylephrine were not inhibited by L-ARG when preparations were incubated from the beginning of the experiment with 1 mM cycloheximide, thus suggesting a dependence on protein synthesis of the attenuation of contraction seen with L-ARG. Intact aortic rings processed for NADPH diaphorase histochemistry, a putative marker for NO synthase, showed NADPH diaphorase reactivity only in the endothelial layer and in the adventitia.(ABSTRACT TRUNCATED AT 250 WORDS)
我们使用一种公认的一氧化氮（NO）合成抑制剂Nω-硝基-L-精氨酸甲酯（L-NAME），通过大鼠胸主动脉环来检验血管组织中存在非内皮源性NO的假说，这些胸主动脉环中的内皮细胞已通过机械磨损去除，完全丧失了内皮依赖性舒张功能。通过记录α-肾上腺素能激动剂去氧肾上腺素诱导的制剂浓度依赖性收缩来测试肌肉的收缩性。在激动剂刺激之前，用L-NAME孵育30分钟至2小时，对Wistar-Kyoto正常血压大鼠（WKY）和自发性高血压大鼠（SHR）主动脉的收缩性没有显著影响。然而，用1 mM L-精氨酸（L-ARG）孵育30分钟，然后在标准Krebs溶液中洗涤1小时的制剂，对去氧肾上腺素的收缩反应在WKY和SHR中均显著降低。在这些用L-ARG预处理的制剂中，L-NAME显著增加了WKY和SHR的收缩性；这种作用被L-ARG阻止，但不被D-精氨酸阻止。当从实验开始就用1 mM环己酰亚胺孵育制剂时，L-ARG对去氧肾上腺素的反应没有受到抑制，因此表明L-ARG所见的收缩减弱依赖于蛋白质合成。对完整主动脉环进行NADPH黄递酶组织化学处理（一种推测的NO合酶标志物），结果显示NADPH黄递酶反应仅在内皮层和外膜中出现。（摘要截选至250字）
