高血压性脑血管功能损伤的临界关闭压评价

背景近来提出的临界关闭压在脑血流自动调节中起着关键作用,是脑循环的有效下游压,可客观反映动态调节的脑血管紧张度,即血管平滑肌收缩舒张的功能状态.目的利用临界关闭压动态评价高血压对脑微动脉平滑肌收缩功能的损伤及其与病理形态改变间的关系.设计随机对照的实验. 单位广州医学院第二附属医院神经科学研究所、中山大学附属第一医院神经科.材料实验于2002-07/2003-08在中山大学生理科学实验室进行.选择健康雄性SD大鼠160只,随机分为对照组和高血压组,每组80只.方法高血压组用双肾双夹法复制成易卒中型肾血管性高血压大鼠模型.对照组除不上银夹外,其余处理同高血压组.两组动物在术后的第2,4,6,8,10,12,14及16周8个时间点各随机选取10只进行动脉血压、临界关闭压的测定.测定完毕后在麻醉状态下取大鼠额顶叶脑组织,制成切片,定量分析脑微动脉的形态变化.主要观察指标①两组大鼠术后不同时间点动脉血压、临界关闭压.②两组大鼠术后不同时间点脑微动脉形态参数.结果160只大鼠均进入结果分析.①高血压组平均动脉压于术后第6周起明显升高,均显著高于对照组(P＜0.05).②高血压组大鼠术后脑血管临界关闭压逐步升高,于术后14,16周明显高于对照组(63.75±7.43),(37.28±3.68)mm Hg;(67.37±15.57),(38.39±7.41)mm Hg,P＜0.05].③高血压组大鼠脑内微动脉的中膜厚度增加非常明显,于第8周后显著大于对照组(P＜0.05).④临界关闭压的升高与平均动脉压、脑内微动脉的中膜厚度呈正相关(r=0.906 93,0.811 36,P均＜0.05).并且血压升高的初期和血压较高后临界关闭压变化较明显,于血压上升明显期则改变不显著,呈倒"S"形改变(R2=0.996 2,P＜0.05).结论高血压形成后脑微动脉平滑肌的收缩程度随动脉血压的动态升高而加强,血管紧张度相应提高,并且在高血压初期和血压较高后改变比较明显.

Functional evaluation of hypertensive cerebrovascular injury by critical closing pressure

BACKGROUND: Critical closing pressure (CCP) is recently thought to play a key role in cerebral blood flow autoregulation as an effective downstream pressure of cerebral circulation and can objectively reflect the cerebrovascular tone, namely the vascular smooth muscle contraction and diastole, which is subjected to dynamic modulation.OBJECTIVE: To dynamically assess the hypertension-induced damage of the contraction function of cerebral microvascular smooth muscles and its correlation with morphological changes based on CCP evaluation.DESIGN: Randomized controlled experiment.SETTING: Institute of Neural Science of Second Hospital Affiliated to Guangzhou Medical College and Department of Neurology, First Hospital Affiliated to Sun Yet-san University.MATERIALS: The experiment was carried out at the Laboratory of Physiological Science of Sun Yet-san University between July 2002 and August 2003. Totally 160 health male SD rats were randomized into control group and hypertension group with 80 rats in each group. METHODS: Stroke-prone renovas cular hyp ortonsive rats were established in rats of the hypertension group by bilateral renal artery occlusion with two clips. The rats in the control group were not subjected to the occlusion with other treatments identical to those of the hypertension group. At the time points of 2, 4, 6, 8, 10, 12, 14 and 16 weeks after operation, respectively, 10 rats were randomly selected from each of the two groups for determination of arterial pressure and CCP. After the measurements the frontal-parietal lobe was obtained from the anaesthetized rats and cut into slices for quantitative analysis of the morphological changes in cerebral microvessels.different postoperative time points.mean arterial pressure in hypertension group obviously increased from the 6th postoperative week with significant difference from that of the control after operation to a level significantly higher than that of the control group at postoperative 14 and 16 weeks (63.75±7.43) vs (37.28±3.68) mm Hg and (67.37±15.57) vs (38.39t7.41) mm Hg, respectively, P ＜ 0.05].significance from that of the control group at the 8th postoperative week (Paverage arterial pressure and cerebral arteriole tunica media (r=0.906 93,0.811 36, respectively, P ＜ 0.05). The changes in CCP was more obvious in the early and advanced stages of blood pressure elevation, but not so manifest during obvious blood pressure increment, displaying an inverted S-shaped curve of changes (R2=0.996 2, P ＜ 0.05).CONCLUSION: Contraction of the cerebrovascular smooth muscles is enhanced with the dynamic increment of arterial pressure after the development of hypertension. Vascular tone increase is more manifest during the early and advanced stages of hypertension.