间歇性气囊挤压大鼠腿部对挤压部位和远端骨骼肌一氧化氮合酶mRNA表达的影响

NOSs mRNA EXPRESSION IN SKELETAL MUSCLE AFTER IPC APPLICATION TO RAT LEG

目的 :为了进一步了解间歇性气囊挤压法 ( Intermittent pneumatic compression,IPC)挤压大鼠腿部与一氧化氮 ( NO)的关系。方法 :检测了大鼠骨骼肌中 3种一氧化氮合酶 ( NOS)同工酶 :神经型 NOS( n NOS) ;诱导型 NOS( i NOS)和内皮细胞型 NOS( e NOS) m RNA在 IPC作用后的表达变化。 2 5只 SD大鼠被随机分为 3个模拟实验组和 4个 IPC实验组。每只鼠取右侧胫前肌( AT)和提睾肌 ( CM)作为正常对照。 IPC组挤压 0 .5 ,1,和 5 h,及挤压 5 h加等待 4h,模拟实验组除不挤压外 ,其他操作均与实验组相同 ,然后分离左侧 AT和 CM作为处理后样品。所有样品应用 RT-PCR进行 NOS m RNA测定。以样品中看家基因 2 ,3 -二羟基丙醛 -3 -磷酸脱氢酶 ( GAPHD) c DNA为内参 ,与 NOS c DNA共同扩增。 PCR产物电泳条带密度用 NIH图像分析软件定量 ,并以与正常对照的对比值作为变化比率。结果 :在 IPC作用 0 .5、1和 5 h后 ,e NOSm RNA显著上升 ,在 AT中分别达到正常对照的 1.2 ,1.8和2 .6倍 ;在 CM中分别达到 1.2 ,1.8和 2 .7倍 ,而其他 NOS,除 5 h IPC组的 n NOS外 ,总体表现下调。在 IPC作用 1h加等待 4h组中 ,e NOS m RNA回复至正常对照水平。结论 :该结果证实了 IPC产生的机械压力至少部分增加了血管壁的剪切压 ,使内皮细?

Objective:Our earlier studies indicated that the application of intermittent pneumatic compression (IPC) to rat hindlimbs promoted distant muscle microcirculation, possibly through the release of NO. This study measured changes of mRNA coding three NO synthase isoforms, neuronal NOS (nNOS), endothelial NOS (eNOS) and inducible NOS (iNOS), in local and distant skeletal muscles after the application of IPC.Methods:25 SD rats were divided into 3 sham and 4 IPC groups. The left anterior tibialis (AT) and cremaster muscle (CM) was removed from each rat as normal controls. The right TA (as a local muscle) and CM (as a distant muscle) were removed following a 30 min, 60 min, 5hrs and 1hr+4hrs waiting of IPC application on hindlimbs in the IPC group or a same time elapse without IPC in the sham groups. Total RNA was extracted from each sample and the NOS mRNA was measured by Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR). The density of PCR products was determined by image analysis software, normalized to a housekeeping gene-Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) that was co-amplified in the same PCR system, and expressed as a ratio relative to normal controls.Results:the eNOS mRNA was significantly up-regulated, increased to 1.2, 1.8, and 2.6 fold in AT, and 1.2, 1.8, and 2.7 fold in CM following IPC application for 0.5, 1h, and 5h, while n- and i-NOS mRNAs were down-regulated. In the 1 + 4h group, eNOS mRNA came back to normal level.Conclusion:The results further confirm that the mechanical pressure produced by IPC increases the shear stress on the vascular wall, thereby stimulating endothelial cells to release NO products and subsequently promoting microcirculation in local and distant muscles. A potential pathway appears to involve the release of eNOS by endothelial cells to effect vessel dilation. [