Keep R F, Cawkwell R D, Jones H C
Brain Res. 1987 Jun 9;413(1):45-52. doi: 10.1016/0006-8993(87)90152-1.
Rats, 20 days old, were fed a diet containing 20% KCl for 10 days. At 30 days these rats had lower body, brain and choroid plexus weights than matched controls and plasma [K+] was increased to 7.5 mM compared to 4.1 mM for controls. Cerebrospinal fluid (CSF) [K+] and bulk fluid secretion were not changed by the high K+ diet but there was a mild metabolic acidosis. The fourth ventricle choroid plexus was prepared for transmission electron microscopy and the structure of the epithelium analysed by quantitative stereology. The high K+ rats had a large increase in the mitochondrial volume fraction of the epithelium due to a 36% increase in individual mitochondrial volume. The high-K+ rats also had a decrease in the apical surface density of the epithelium due to a 41% decrease in the height of the microvilli. It is concluded that the increase in mitochondrial volume may provide the additional energy required for the increased transport of K+ out of the CSF in hyperkalaemia. The reduction in height of the microvilli could be a means for maintaining a normal CSF bulk secretion rate despite the increase in K+ transport required to maintain normal CSF [K+] in hyperkalaemia.
给20日龄的大鼠喂食含20%氯化钾的饲料，持续10天。30日龄时，这些大鼠的体重、脑重和脉络丛重量均低于配对的对照组，血浆[K⁺]浓度升至7.5毫摩尔/升，而对照组为4.1毫摩尔/升。高钾饮食并未改变脑脊液（CSF）[K⁺]和总体液分泌，但出现了轻度代谢性酸中毒。制备第四脑室脉络丛用于透射电子显微镜检查，并通过定量体视学分析上皮结构。高钾大鼠上皮细胞线粒体体积分数大幅增加，单个线粒体体积增加了36%。高钾大鼠上皮细胞顶端表面密度降低，微绒毛高度降低了41%。结论是，线粒体体积增加可能为高钾血症时将更多K⁺从脑脊液中转运出去提供额外能量。微绒毛高度降低可能是一种机制，尽管高钾血症时为维持正常脑脊液[K⁺]需要增加K⁺转运，但仍能保持脑脊液总体分泌速率正常。
