血管外膜源一氧化氮对尾加压素Ⅱ诱导的血管平滑肌增殖的抑制作用

The inhibitory effects of adventitia-derived nitric oxide on the proliferation of vascular smooth muscle cells induced by urotensin Ⅱ

目的观察血管外膜生成的一氧化氮(NO)对尾加压素Ⅱ(UrotensionⅡ,UⅡ)刺激的血管平滑肌细胞(VSMC)增殖的影响及机制。方法取大鼠胸主动脉,去除内皮,分以下几组进行组织孵育10h①完整外膜血管组;②单纯中膜组;③中膜与剥离的外膜共育组;④中膜与用L-N-硝基精氨酸(L-NNA)预处理的外膜共育组。每例胸主动脉剪为二段,分两个亚组UⅡ(10-7mol/L)组和对照组。3H-胸腺嘧啶(3H-TdR)掺入法检测各组VSMC的细胞增殖。另取大鼠腹主动脉外膜,用10-8和10-7mol/LUⅡ刺激4h。Griess法测血管外膜生成的亚硝酸盐(NO2-)含量,3H-L-精氨酸(3H-L-Arg)标记的同位素法测定外膜一氧化氮合酶(NOS)活性。结果①各UⅡ亚组3H-TdR掺入比相应对照组分别增加62.9%～98.3%(均P<0.01)。②在10-7mol/LUⅡ刺激下,完整外膜组及中膜+外膜组的3H-TdR掺入分别比单纯中膜组低20.5%和20.3%(P<0.01);中膜+L-NNA预处理的外膜组3H-TdR掺入分别比中膜+外膜组及完整外膜组高27.1%和27.3%(P<0.01),而与单纯中膜组差异无显著性(P>0.05)。③与对照组相比,10-8和10-7mol/L的UⅡ使外膜NOS活性分别增加92.1%和177%(P<0.01);使外膜生成的NO2-含量分别增加88.7%和178%(P<0.01)。结论血管外膜生成的NO可抑制UⅡ刺激的VSMC的增殖,其抑制作用为UⅡ激活的血管外膜NOS/

Objictive To observe the effect of adventitial nitric oxide (NO) on the proliferation of vascular smooth muscle cells (VSMC) induced by urotensinⅡ(UⅡ) and investigate the significance of adventitia-derived NO in vascular remodeling. Methods Rat thoracic aortae (n=24) were dissected and the endothelia removed. The vessels were divided into four groups (n=6) as following and were incubated for 10 hours:①vessel with intact adventitia; ②media alone; ③media and isolated adventitia; ④media and adventita pretreated with 10^-5 mol/L L-NNA. Every vessel of these groups was cut into two parts, which were incubated with or without 10^-7 mol/L UⅡ,respectively. The proliferation of VSMC was measured by^3 H-TdR incorporation. Adventitia-derived NO production (NO_2-) was determined by Griess method and adventitial nitric oxide synthase (NOS) activity by the transformation of^3 H-L-Arg to^3 H-L-Citrulline,respectively. Results ①The^3 H-TdR incorporation of VSMC in each UⅡ subgroup was significantly elevated up to 62.9%～98.3% compared with corresponding control subgroup. ②When thoracic aortae were stimulated by 10^-7 mol/L UⅡfor 10 hours, the^3 H-TdR incorporation of VSMC in the intact adventitia group and the media + adventitia group decreased by 20.5% and 20.3% compared with the media alone group,respectively; the^3 H-TdR incorporation of VSMC in the group of media + adventitia pretreated with L-NNA increased by 27.1% and 27.3% compared with the media + adventitia group and the intact adventitia group,respectively,and there was not significant difference compared with the media group. ③After incubation with 10^-8 or 10^-7 mol/L UⅡfor 4 hours, the abdominal aortic adventitial NOS activities were increased up to 92.1% and 177% and adventitia-derived NO_2-were increased up to 88.7% and 178% compared with control group respectively. Conclusions The results show that vascular adventitia may inhibit proliferation of medial VSMC induced by UⅡ, which was mediated by adventitial NOS/NO pathway. Our findings suggest that adventitia-derived NO may play an important part in regulating the vascular remodeling of cardiovascular diseases.