LEVELS OF ADENOSINE AND ADENINE-NUCLEOTIDES IN SLICES OF RAT HIPPOCAMPUS
LEVELS OF ADENOSINE AND ADENINE-NUCLEOTIDES IN SLICES OF RAT HIPPOCAMPUS
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DOI：
10.1016/0006-8993(84)90823-0
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发表时间：
1984-01-01
期刊：
影响因子：
2.9
通讯作者：
LINDSTROM, K
中科院分区：
文献类型：
--
作者：
FREDHOLM, BB;DUNWIDDIE, TV;LINDSTROM, K
在体外培养的大鼠海马片上测定ATP、ADP、AMP、IMP、腺苷、肌苷和cAMP。采伐后即刻，ATP较低(3.5.+-.0.6nmol/mg蛋白)和高AMP(8.6+-)。0.9nmol/mg)，能荷仅为0.34±-。0.02。在接下来的90分钟内，能量电荷逐渐正常化(至0.92.+-.0.01)，部分是由于AMP转化为ATP，但主要是分解为腺苷和其他嘌呤，它们在孵育介质中被回收。总嘌呤含量从.apprx开始下降。切割后1h为18~10nmol/mg蛋白。在老年大鼠脑片中，准备60min后能量负荷低于年轻大鼠，而cAMP和腺苷水平高于年轻大鼠。腺苷拮抗剂8-苯基-茶碱有促进切片制备后反应性恢复的趋势。以10 Hz频率刺激兴奋性传入纤维5min，对脑片中的嘌呤含量无明显影响，而低氧使能荷显著降低，并有升高腺苷水平的趋势。这些变化发生得比电生理反应性的下降稍晚一些。8-苯基茶碱能在一定程度上延缓低氧条件下突触反应幅度的下降。海马片的活性部分约占组织的一半，其腺嘌呤核苷酸和腺苷的水平与在完整的大鼠大脑中发现的类似。脑片制备后电生理功能的恢复与能量电荷、腺苷水平和cAMP浓度的正常化是平行的。切断后缺乏电生理活动，这种反应在长时间传入刺激或低氧后的减少可能与脑片中嘌呤浓度的变化有关。虽然腺苷在脑片中的积聚可能有助于电生理反应的抑制，但它可能不是导致突触反应性降低的主要因素。
ATP, ADP, AMP, IMP, adenosine, inosine and cAMP were measured in slices of the rat hippocampus maintained in vitro. Immediately following cutting ATP was low (3.5 .+-. 0.6 nmol/mg protein) and AMP high (8.6 .+-. 0.9 nmol/mg), giving an energy charge of only 0.34 .+-. 0.02. Over the next 90 min the energy charge gradually normalized (to 0.92 .+-. 0.01), partly due to conversion of AMP to ATP, but mainly to breakdown to adenosine and other purines which were recovered in the incubation medium. Total purine content decreased from .apprx. 18 to 10 nmol/mg protein in the 1st h following cutting. In slices from old rats, the energy charge was lower 60 min following preparation than in younger rats, while cAMP and adenosine levels were higher. The adenosine antagonist 8-phenyl-theophylline tended to enhance the recovery of responsiveness after preparation of the slices. Stimulation of excitatory afferent fibers at a frequency of 10 Hz for 5 min did not significantly alter the purine levels in brain slices, while hypoxia decreased the energy charge significantly and tended to increase adenosine levels. These changes occurred somewhat later than the fall in electrophysiological responsiveness. 8-Phenyl-theophylline was able to delay somewhat the decline in the amplitude of synaptic responses under hypoxic conditions. The viable part of the hippocampal slice, which accounts for about half of the tissue, has levels of adenine nucleotides and adenosine which are similar to those found in the intact rat brain. The return of electrophysiological function following slice preparation is paralleled by a normalization of the energy charge, the adenosine level and the concentration of cAMP. The absence of electrophysiological activity following cutting, and the decreases in such responses following either prolonged afferent stimulation or hypoxia may be related to changes in purine concentration in the slice. Although adenosine accumulating in the slice may contribute to the depression of electrophysiological responses it is probably not the major factor responsible for the reduction in synaptic responsiveness.