Kim S C, Seo K K, Kim H W, Lee M Y
Department of Urology; Department of Physiology, College of Medicine, Chung-Ang University, Seoul, Korea.
Int J Androl. 2000;23 Suppl 2:26-9. doi: 10.1046/j.1365-2605.2000.00007.x.
The aim of this study was to investigate the effects of isolated lipoproteins and triglyceride (TG), and the effects of combined oxidized low density lipoprotein (LDL) plus TG and the combined oxidized LDL plus high density lipoprotein (HDL) on the contractility and relaxation response of rabbit cavernous smooth muscle. Cavernous muscle strips from New Zealand White rabbits were studied in organ chambers for isometric tension measurement. The strips were exposed to HDL, LDL, oxidized LDL, TG, combined oxidized LDL plus TG and combined oxidized LDL plus HDL for 30 min. Both HDL and LDL did not affect contraction and relaxation responses of the cavernous muscles. The oxidized LDL did not affect norepinephrine (NE)-induced contractility of the strips, but significantly (p < 0.05) decreased the relaxation response to endothelium-dependent agonist, acetylcholine (Ach). Non-specific NO synthase inhibitor (L-NAME) completely inhibited the relaxation response to Ach, and L-arginine partially improved the diminished relaxation. TG did not significantly change the relaxation responses to Ach, but decreased the contractility of cavernous muscle to NE. Neither the combined oxidized LDL plus TG nor oxidized LDL plus HDL had significant synergistic or detoxication effects on the contractility and relaxation responses. In conclusion, oxidized LDL may have acute toxic effects on the endothelium-dependent, NO-mediated relaxation, but not on the contractility, of rabbit cavernous smooth muscle. TG may decrease contractility of the cavernous muscle. There may be neither synergistic nor detoxication effects on the contractility and relaxation response when TG or HDL is added to the oxidized LDL.
本研究旨在探讨分离的脂蛋白和甘油三酯（TG）的作用，以及氧化低密度脂蛋白（LDL）与TG联合作用和氧化LDL与高密度脂蛋白（HDL）联合作用对兔海绵体平滑肌收缩性和舒张反应的影响。在器官浴槽中对新西兰白兔的海绵体肌条进行等长张力测量研究。将肌条分别暴露于HDL、LDL、氧化LDL、TG、氧化LDL与TG联合以及氧化LDL与HDL联合环境中30分钟。HDL和LDL均未影响海绵体肌的收缩和舒张反应。氧化LDL不影响去甲肾上腺素（NE）诱导的肌条收缩性，但显著（p<0.05）降低了对内皮依赖性激动剂乙酰胆碱（Ach）的舒张反应。非特异性一氧化氮合酶抑制剂（L-NAME）完全抑制了对Ach的舒张反应，而L-精氨酸部分改善了减弱的舒张反应。TG对Ach的舒张反应无显著改变，但降低了海绵体肌对NE的收缩性。氧化LDL与TG联合以及氧化LDL与HDL联合对收缩性和舒张反应均无显著的协同或解毒作用。总之，氧化LDL可能对兔海绵体平滑肌的内皮依赖性、NO介导的舒张有急性毒性作用，但对收缩性无影响。TG可能降低海绵体肌的收缩性。当向氧化LDL中添加TG或HDL时，对收缩性和舒张反应可能既无协同作用也无解毒作用。
