CHANGES IN EXTRACELLULAR CALCIUM AND MAGNESIUM AND SYNAPTIC TRANSMISSION IN ISOLATED MOUSE SPINAL-CORD
CHANGES IN EXTRACELLULAR CALCIUM AND MAGNESIUM AND SYNAPTIC TRANSMISSION IN ISOLATED MOUSE SPINAL-CORD
复制标题
DOI：
10.1016/0006-8993(89)90513-1
复制
发表时间：
1989-05-08
期刊：
影响因子：
2.9
通讯作者：
SOMJEN, GG
中科院分区：
文献类型：
--
作者：
CZEH, G;SOMJEN, GG
半切小鼠脊髓保持在体外和浴中的钙[Ca 2 +]和镁[Mg 2 +]的浓度是不同的。在含有1.2 mM的[Ca 2 +]和[Mg 2 +]刺激背根（DR）的对照溶液中，在相邻的DR中诱发代表“输入”的初始纤维齐射;通过背侧灰质的体积传导记录的popstsynaptic复合尖峰，背角反应（DHR）;和缓慢的背根电位（DRP）。在刺激节段的腹根中诱发单突触反射（VRR 1）。降低[Ca ~（2+）]或[Mg ~（2+）]可增强纤维的排流，降低[Ca ~（2+）]可抑制纤维的排流。在1.8mM [Ca ~（2+）]及以上时，出现“经典"背根反射（DRR）和GABA依赖的延迟VR反射（VRR_2）。反射的传输在2.4和3.6 mM [Ca 2 +]之间是最大的，而DRP在约4.8 mM时是最大的。在升高[Mg 2 +]和低[Ca 2 +]中，所有突触传递的反应（DRR，DRP和VRR）被抑制。[Ca ~（2+）]和[Mg ~（2+）]对DRR、DRR和VRR ~ 2的影响大于对DHR和VRR ~ 1的影响。[Ca ~（2+）]和[Mg ~（2+）]同时变化的效应部分相互抵消。我们的结论是，低到中度升高[Ca 2 +]主要影响突触前末梢的递质释放，在非常高的[Ca 2 +]神经元兴奋性域的抑郁症。Ca ~（2+）和Mg ~（2+）对GABA能传递的影响尤为显著。
Hemisected mouse spinal cords were maintained in vitro and the concentrations of calcium [Ca2+] and of magnesium [Mg2+] in the bath were varied. In control solution containing 1.2 mM of both [Ca2+] and [Mg2+] stimulation of a dorsal root (DR) evoked in an adjacent DR an initial fiber volley representing ''input''; a popstsynaptic compound spike recorded by volume conduction from dorsal gray matter, the dorsal horn response (DHR); and a slow dorsal root potential (DRP). In the ventral root of the stimulated segment a monosynaptic reflex (VRR1) was evoked. The fiber volley was enhanced by lowering [Ca2+] or [Mg2+] and depressed [Ca2+]. At 1.8 mM [Ca2+] and above, the ''classical'' dorsal root reflex (DRR) and a GABA-dependent delayed VR reflex (VRR2) appeared. Transmission of reflexes was maximal between 2.4 and 3.6 mM [Ca2+], while DRP was maximal at about 4.8 mM. In elevated [Mg2+] and in low [Ca2+] all synaptically transmitted responses (DRR, DRP and VRR) were depressed. The influence of both [Ca2+] and [Mg2+] was stronger on DRR, DRR and VRR2 than on DHR and VRR1. The effects of simultaneous changes of [Ca2+] and [Mg2+] partially cancelled each other. We conclude that low to moderately elevated [Ca2+] mainly influences the release of transmitter from presynaptic terminals; at very high [Ca2+] the depression of neuronal excitability domainates. The effects of Ca2+ and Mg2+ on GABAergic transmission are especially marked.