Modification of activity-dependent increases in cerebellar blood flow by extracellular potassium in anaesthetized rats
Modification of activity-dependent increases in cerebellar blood flow by extracellular potassium in anaesthetized rats
复制标题
DOI：
10.1111/j.1469-7793.1999.00281.x
复制
发表时间：
1999-10-01
影响因子：
5.5
通讯作者：
Lauritzen, M
中科院分区：
文献类型：
--
作者：
Caesar, K;Akgören, N;Lauritzen, M
1.用离子选择性微电极和激光多普勒血流仪在大鼠小脑皮质中研究了钾离子介导活动依赖性脑血流量增加的假设。刺激平行纤维和攀爬纤维，以及皮层微量注射KCl，均可引起小脑血流量（CeBF）和细胞外钾离子浓度（[K+]（o））的增加.对于平行纤维刺激，[K+]（o）最大增加至6.3 +/- 0.5 mM，CeBF最大增加至122 +/-11%。攀爬纤维刺激使[K+]（o）最大增加至4.4 +/- 0.2 mM，CeBF最大增加至157 +/-20%。这表明[K+]（o）和CeBF的不同最大值取决于传入系统的激活。平行纤维或攀爬引起的[K+]（o）和CeBF反应：纤维刺激在刺激开始时迅速增加，但在刺激期的剩余时间和恢复到基线时表现出不同的时间过程.将KCl微量注射到皮质中使[K+]（o）增加到与平行纤维刺激诱发的水平相当的水平。相应的CeBF增加是相同的，或小于，平行纤维刺激，比攀爬纤维刺激小得多。这表明除了[K+]（o）之外的介质对于活动依赖性脑血流量增加是重要的。本研究表明，[K+]（o）的增加参与了平行纤维系统中CeBF的调节，但对攀援纤维系统中CeBF的调节作用有限。K+是活动依赖性血流量增加的主要介质的假设可能并不普遍适用于所有脑区和所有类型的神经元刺激。
1. The hypothesis that potassium ions mediate activity-dependent increases of cerebral blood flow was examined in rat cerebellar cortex using ion-selective microelectrodes and laser-Doppler flowmetry. Increases of cerebellar blood flow (CeBF) and extracellular potassium concentration ([K+](o)) were evoked by stimulation of parallel fibres and climbing fibres, and by microinjection of KCl into the cortex.2. For parallel fibre stimulation, there was a maximal increase in [K+](o) to 6.3 +/- 0.5 mM and in CeBF of 122 +/- 11%. Climbing fibre stimulation gave a maximal increase in [K+](o) to 4.4 +/- 0.2 mM and in CeBF of 157 +/- 20%. This indicates different maxima for [K+](o) and CeBF, dependent on the afferent system activated.3. [K+](o) and CeBF responses evoked by parallel fibre or climbing: fibre stimulation increased rapidly at the onset of stimulation, but exhibited different time courses during the remainder of the stimulation period and during return to baseline.4. Microinjections of KCl into the cortex increased [K+](o) to levels comparable to those evoked by parallel fibre stimulation. The corresponding CeBF increases were the same as, or smaller than, for parallel fibre stimulation, and much smaller than for climbing fibre stimulation. This suggests that mediators other than [K+](o) are important for activity-dependent cerebral blood flow increases.5. The present study showed that increased [K+](o) is involved in CeBF regulation in the parallel fibre system, but is of limited importance for CeBF regulation in the climbing fibre system. The hypothesis that K+ is a major mediator of activity-dependent blood flow increases is probably not generally applicable to all brain regions and all types of neuronal stimulation.