Rauca C, Kammerer E, Matthies H
Biomed Biochim Acta. 1985;44(11-12):1621-31.
The effect of K+-evoked acetylcholine (ACh) release on uptake and acetylation of choline (Ch) in hippocampus slices of rats was studied by use of two different temporal schedules of incubation with labeled precursor and K+-stimulation of tissue. When the incubation with labeled Ch was performed before K+-stimulation, a significant increase of ACh release up to about 400% could be observed. From hippocampus tissue Ch and ACh were extracted as free, labile bound and stable bound fractions. Immediately after the end of potassium stimulation only the ACh radioactivity of the labile bound fraction was decreased, whereas the Ch radioactivities were not changed. In a second series of experiments the K+-evoked ACh release was finished immediately, 10 or 25 min before incubation with labeled precursor. At this time the ACh radioactivity in the incubation medium was normalized. On the other hand, the Ch and ACh radioactivities in the hippocampus tissue increased and returned to control values by different time courses. 30 min after potassium stimulation the ACh radioactivities were still increased, whereas the Ch radioactivities were already normalized to control level. The calculation of the totals of released ACh radioactivity and Ch and ACh radioactivities of tissue suggests that the potassium evoked release leads to a higher uptake and acetylation irrespective of whether the stimulation was carried out before or after the incubation with labeled precursor.
利用两种不同的时间安排，即先用标记前体孵育组织，然后用钾离子刺激组织，研究了钾离子诱发的乙酰胆碱（ACh）释放对大鼠海马切片中胆碱（Ch）摄取和乙酰化的影响。当在钾离子刺激前进行标记胆碱的孵育时，可以观察到乙酰胆碱释放显著增加，高达约400%。从海马组织中提取胆碱和乙酰胆碱，分为游离、不稳定结合和稳定结合部分。钾离子刺激结束后，仅不稳定结合部分的乙酰胆碱放射性降低，而胆碱放射性未改变。在第二系列实验中，在与标记前体孵育前10或25分钟，立即完成钾离子诱发的乙酰胆碱释放。此时，孵育培养基中的乙酰胆碱放射性恢复正常。另一方面，海马组织中的胆碱和乙酰胆碱放射性增加，并通过不同的时间进程恢复到对照值。钾离子刺激30分钟后，乙酰胆碱放射性仍增加，而胆碱放射性已恢复到对照水平。对释放的乙酰胆碱放射性总量以及组织中胆碱和乙酰胆碱放射性的计算表明，无论刺激是在与标记前体孵育之前还是之后进行，钾离子诱发的释放都会导致更高的摄取和乙酰化。
