Kunkler P E, Kraig R P
Department of Neurology, The University of Chicago, Chicago, Illinois 60637, USA.
J Neurosci. 1998 May 1;18(9):3416-25. doi: 10.1523/JNEUROSCI.18-09-03416.1998.
Although intercellular Ca2+ waves resemble spreading depression (SD) and occur in hippocampal organ cultures (HOTCs), SD has not been reported in these cultures. Accordingly, electrophysiological and Ca2+ imaging techniques were used to examine potential interrelations between Ca2+ waves and electrophysiological changes of SD. Our results show, for the first time, that HOTCs can support SD. Furthermore, two distinct Ca2+ waves were found to precede SD. The first traveled >100 micron/sec along the pyramidal cell dendritic layer. The second subsequently traveled mostly perpendicular to the pyramidal cell layer from CA3 (or CA1) but also in all directions from its area of initiation. This second, slower wave spread with the interstitial DC change of SD at millimeters per minute but always ahead of it by 6-16 sec. Heptanol, which uncouples gap junctions, blocked both of these Ca2+ waves and SD. Thus, two types of Ca2+ waves occur with the initiation and propagation of SD. The first might reflect interneuronal changes linked by gap junctions, whereas the second might stem from interastrocyte changes linked via similar connections. Because individual cells can be followed in space and time for protracted periods in HOTCs, this preparation may be ideal for studies designed to explore not only the mechanisms of SD but also the long-term consequences of SD, such as ischemic tolerance.
尽管细胞间钙离子波类似于扩散性抑制（SD）且在海马器官培养物（HOTCs）中出现，但在这些培养物中尚未报道过SD。因此，采用电生理和钙离子成像技术来研究钙离子波与SD电生理变化之间的潜在相互关系。我们的结果首次表明，HOTCs能够支持SD。此外，发现有两种不同的钙离子波先于SD出现。第一种沿着锥体细胞树突层以>100微米/秒的速度传播。第二种随后主要从CA3（或CA1）垂直于锥体细胞层传播，但也从其起始区域向各个方向传播。这第二种较慢的波以每分钟几毫米的速度随着SD的间隙性直流变化传播，但总是比它提前6 - 16秒。解偶联缝隙连接的庚醇可阻断这两种钙离子波和SD。因此，两种类型的钙离子波随着SD的起始和传播而出现。第一种可能反映了由缝隙连接连接的中间神经元变化，而第二种可能源于通过类似连接连接的星形胶质细胞间变化。由于在HOTCs中可以在长时间内对单个细胞进行空间和时间上的跟踪，这种制备方法可能是不仅用于探索SD机制，而且用于探索SD的长期后果（如缺血耐受性）的研究的理想选择。
