易卒中型肾血管性高血压大鼠的脑血流自动调节下限与最低耐受压

The lower limit and the lowest endurance blood pressure of cerebral blood flow autoregulation in RHRSP.

目的 研究易卒中型肾血管性高血压大鼠 (RHRSP)的脑血流 (CBF)自动调节下限及其最低耐受压。 方法 用氢清除法测定RHRSP和正常SD大鼠在不同低血压水平时 ,一侧顶枕交界区皮质和海马的局部CBF(rCBF) ;72小时后计算RHRSP和SD大鼠海马CA1 区神经细胞 (CA1 NC)线粒体的体密度 (Vv)、比表面 (δ)、平均体积 ( V)和数密度 (Nv) , 结果 正常SD大鼠在平均动脉压 (MABP)为 1 0 67kPa、9 3 3kPa和 8kPa时 ,rCBF值无显著减少。在MABP为 1 0 67kPa时 ,RHRSP的rCBF值显著减少 ;超微结构观察发现CA1 NC无明显缺血改变 ,当MABP为 9 3 3kPa时 ,CA1 NC缺血明显 ;细胞形态分析发现 9 3 3kPa组与 1 0 67kPa组比较 ,前者线粒体的Vv和 V显著增大 ,δ和Nv显著减小。 结论 RHRSP的CBF自动调节下限上移至 1 0 67kPa,并与其最低耐受压十分接近 。

Objective To investigate the lower limit and the lowest endurance blood pressure of cerebral blood flow (CBF) autoregulation in stroke prone renovascular hypertensive rats(RHRSP) Methods Hydrogen clearance method was used to measure the changes of regional CBF (rCBF) at one side of parieto occipotal junctional cortex and hippocampus in RHRSP and normontension Spraque dawley(SD) rats respectively during periods of different degrees of hypotension Seventy two hours later, the mitochondrial volume density(Vv), specific surface(δ), average volume() and numerical density (Nv) in nerve cells of CA 1 hippocampus were calculated Results There was not obvious reduction for rCBF in normotension SD rats when mean arterial blood pressure (MABP) was lowered to 10 67kPa, 9 33kPa, 8kPa respectively ( P >0 05) In RHRSP, when MABP was lowered to 10 67kPa, the rCBF decreased significantly ( P <0 05), there were no obvious ischemic change in ultrastructure of nerve cells of CA 1 hippocampus The ischemic changes of nerve cells of CA 1 hippocampus were significant when MABP was lowered to 9 33kPa The mitochondrial Vv and were much bigger, δ and Nv were much smaller in the 9 33 kPa than in 10 67 kPa group Conclusions The lower blood pressure limit of CBF autoregulation is shifted to 10 67kPa and it is very close to the lowest endurance blood pressure of CBF autoregulation in RHRSP These results suggest that RHRSP is a practical animal model to be used to study the hypertensive cerebraovascular damage