Dunn W R, Gardiner S M
Department of Physiology and Pharmacology, Queen's Medical Centre, Medical School, University of Nottingham, UK.
Hypertension. 1997 May;29(5):1140-7. doi: 10.1161/01.hyp.29.5.1140.
In this study we examined the structural properties of cerebral and mesenteric resistance arteries isolated from normotensive, Sprague-Dawley (SD) rats (mean arterial pressure [MAP], 110 +/- 3 mm Hg) and hypertensive, transgenic (TG) rats (MAP, 167 +/- 4 mm Hg), which express the mouse Ren-2 renin gene. Vessels were set up in a pressure myograph, and ID and vascular wall thickness were determined at increasing intraluminal pressures. Arteries were subsequently pressurized to the MAP of the animal from which they were isolated and were fixed with glutaraldehyde before being embedded in araldite, sectioned, and examined histologically. The middle cerebral artery (MCA) isolated from SD rats and TG rats had similar media cross-sectional areas. There was no difference in MCA diameter at 10 mm Hg in vessels from TG rats compared with SD rats. However, at higher distending pressures, the diameter of the MCA from TG rats was significantly smaller than that of vessels from SD rats. This reduced ID at the higher pressures was a consequence of a decreased distensibility of the MCA from TG rats (as shown by a leftward shift of the stress-strain relationship in arteries from TG rats) and was not caused by an increase in wall thickness. First- and second-order mesenteric resistance arteries isolated from TG rats displayed an increased wall thickness and media content compared with vessels from SD rats. However, this alteration in mesenteric artery structure did not impinge on the ID of arteries from TG rats; there was no difference in the IDs of mesenteric resistance arteries between the two strains at any distending pressure. These observations show that there are distinct regional alterations in vascular structure in hypertensive TG rats expressing the mouse Ren-2 renin gene. Mesenteric resistance arteries isolated from TG rats display signs of vascular growth, although this structural alteration does not produce a reduction in the ID of these arteries per se. In contrast, cerebral arteries from TG rats do not show increased growth but have a reduced vascular distensibility, which results in a smaller ID compared with vessels from SD rats.
在本研究中，我们检测了从正常血压的斯普拉格-道利（SD）大鼠（平均动脉压[MAP]，110±3 mmHg）和高血压转基因（TG）大鼠（MAP，167±4 mmHg）分离出的脑和肠系膜阻力动脉的结构特性，TG大鼠表达小鼠Ren-2肾素基因。将血管安装在压力肌动描记仪中，在逐渐升高的腔内压力下测定内径（ID）和血管壁厚度。随后将动脉加压至其分离所来自动物的MAP，并在用戊二醛固定后包埋在环氧树脂中，切片并进行组织学检查。从SD大鼠和TG大鼠分离出的大脑中动脉（MCA）具有相似的中膜横截面积。与SD大鼠相比，TG大鼠血管在10 mmHg时的MCA直径没有差异。然而，在更高的扩张压力下，TG大鼠的MCA直径明显小于SD大鼠的血管。在较高压力下ID的减小是TG大鼠MCA扩张性降低的结果（如TG大鼠动脉的应力-应变关系向左移位所示），而不是由壁厚度增加引起的。与SD大鼠的血管相比，从TG大鼠分离出的一级和二级肠系膜阻力动脉显示壁厚度和中膜含量增加。然而，肠系膜动脉结构的这种改变并未影响TG大鼠动脉的ID；在任何扩张压力下，两种品系的肠系膜阻力动脉ID均无差异。这些观察结果表明，表达小鼠Ren-2肾素基因的高血压TG大鼠的血管结构存在明显的区域改变。从TG大鼠分离出的肠系膜阻力动脉显示出血管生长的迹象，尽管这种结构改变本身并未导致这些动脉的ID减小。相比之下，TG大鼠的脑动脉未显示生长增加，但血管扩张性降低，与SD大鼠的血管相比，导致ID更小。
