Lacza Zsombor, W Busija David
Department of Physiology/Pharmacology, Wake Forest University Health Sciences, Medical Center Blvd., Winston-Salem, NC 27157, USA.
Life Sci. 2006 May 1;78(23):2763-6. doi: 10.1016/j.lfs.2005.11.002. Epub 2005 Dec 6.
Urotensin-II (UT-II) is a small circular peptide and is described as the most potent endogenous vasoconstrictor in various vascular beds. However, the in vivo effects of UT-II can be either vasoconstriction or vasodilation depending on the species and the tissue investigated. The present study sought to characterize the vasoactive effect of UT-II in the piglet cerebral circulation in vivo. Pial arteries of 99 +/- 6 microm were visualized with intravital microscopy through a closed cranial window in anesthetized newborn piglets. Topical application of UT-II elicited a weak dose-dependent vasodilation of the arteries (0.001 microM: 3 +/- 3 microm, 0.1 microM: 10 +/- 5 microm, 10 microM: 14 +/- 7 microm). Smaller arteries with an initial diameter below 100 microm showed minimal or no vasodilation, while larger arteries between 100 and 120 microm had a pronounced dose-dependent effect. Systemic application of 15 mg/kg Nomega-nitro-L-arginine-methyl ester (L-NAME) completely inhibited the vasodilation. We conclude that UT-II, in contrast to most other vascular beds, is a weak NO-dependent vasodilator in the piglet pial vasculature.
尾加压素 II（UT-II）是一种小的环状肽，被认为是各种血管床中最有效的内源性血管收缩剂。然而，UT-II 在体内的作用可能是血管收缩或血管舒张，这取决于所研究的物种和组织。本研究旨在表征 UT-II 在新生仔猪脑循环中的血管活性作用。通过在麻醉的新生仔猪的闭合颅窗内进行活体显微镜观察，观察到直径为99±6微米的软脑膜动脉。局部应用UT-II可引起动脉的弱剂量依赖性血管舒张（0.001微摩尔/升：3±3微米，0.1微摩尔/升：10±5微米，10微摩尔/升：14±7微米）。初始直径小于100微米的较小动脉显示出最小的血管舒张或无血管舒张，而直径在100至120微米之间的较大动脉具有明显的剂量依赖性作用。全身应用15毫克/千克的Nω-硝基-L-精氨酸甲酯（L-NAME）可完全抑制血管舒张。我们得出结论，与大多数其他血管床不同，UT-II在仔猪软脑膜血管系统中是一种弱的一氧化氮依赖性血管舒张剂。
