Moufarrij N A, Harik S I
Department of Neurology, University Hospitals of Cleveland, Ohio 44106.
Neurol Res. 1989 Jun;11(2):97-100. doi: 10.1080/01616412.1989.11739869.
Locus ceruleus lesion decreases the density of ouabain binding sites, and presumably Na+, K+-ATPase, in brain microvessels. To determine if this decrease affects the transport of Na+, K+ or water across the blood-brain barrier, we studied the influence of unilateral locus ceruleus lesion on Na+, K+ and water content of the ipsilateral cerebral cortex. Unilateral locus ceruleus lesion depleted norepinephrine in the ipsilateral cerebral cortex but had no effect on tissue Na+, K+ or water under steady-state conditions. When the Na+/K+ exchange pump of the blood-brain barrier was stressed by hyperkalaemia, K+ content in the ipsilateral cerebral cortex rose to higher levels than in the contralateral cortex, but the difference did not reach statistical significance. Locus ceruleus lesion also did not cause significant differences in the cerebral cortical content of water, Na+ or K+ in hyponatraemia. The results suggest that brain water and ion homeostasis are tightly controlled, probably by multiple mechanisms with biological redundancies, so that even a 50% decrease in the density of ouabain binding sites in brain endothelium does not result in significant alterations in brain water, Na+ or K+ content.
蓝斑损伤会降低脑微血管中哇巴因结合位点的密度，推测也会降低钠钾ATP酶的密度。为了确定这种降低是否会影响钠、钾或水通过血脑屏障的转运，我们研究了单侧蓝斑损伤对同侧大脑皮质钠、钾和水含量的影响。单侧蓝斑损伤会使同侧大脑皮质中的去甲肾上腺素耗竭，但在稳态条件下对组织中的钠、钾或水没有影响。当血脑屏障的钠/钾交换泵因高钾血症而受到压力时，同侧大脑皮质中的钾含量升至高于对侧皮质的水平，但差异未达到统计学意义。在低钠血症时，蓝斑损伤也未导致大脑皮质水、钠或钾含量出现显著差异。结果表明，脑水和离子稳态受到严格控制，可能是通过多种具有生物学冗余性的机制，因此即使脑内皮细胞中哇巴因结合位点的密度降低50%，也不会导致脑水、钠或钾含量出现显著改变。
