@article {Bao8740, author = {Juping Bao and Jing James Li and Edward R. Perl}, title = {Differences in Ca2+ Channels Governing Generation of Miniature and Evoked Excitatory Synaptic Currents in Spinal Laminae I and II}, volume = {18}, number = {21}, pages = {8740--8750}, year = {1998}, doi = {10.1523/JNEUROSCI.18-21-08740.1998}, publisher = {Society for Neuroscience}, abstract = {Many neurons of spinal laminae I and II, a region concerned with pain and other somatosensory mechanisms, display frequent miniature {\textquotedblleft}spontaneous{\textquotedblright} EPSCs (mEPSCs). In a number of instances, mEPSCs occur often enough to influence neuronal excitability. To compare generation of mEPSCs to EPSCs evoked by dorsal root stimulation (DR-EPSCs), various agents affecting neuronal activity and Ca2+ channels were applied to in vitro slice preparations of rodent spinal cord during tight-seal, whole-cell, voltage-clamp recordings from laminae I and II neurons. The AMPA/kainate glutamate receptor antagonist CNQX (10{\textendash}20 μm) regularly abolished DR-EPSCs. In many neurons CNQX also eliminated mEPSCs; however, in a number of cases a proportion of the mEPSCs were resistant to CNQX suggesting that in these instances different mediators or receptors were also involved. Cd2+ (10{\textendash}50 μm) blocked evoked EPSCs without suppressing mEPSC occurrence. In contrast, Ni2+ (<=100 μm), a low-threshold Ca2+ channel antagonist, markedly decreased mEPSC frequency while leaving evoked monosynaptic EPSCs little changed. Selective organic antagonists of high-threshold (HVA) Ca2+ channels, nimodipine, ω-Conotoxin GVIA, and Agatoxin IVA partially suppressed DR-EPSCs, however, they had little or no effect on mEPSC frequency. La3+ and mibefradil, agents interfering with low-threshold Ca2+ channels, regularly decreased mEPSC frequency with little effect on fast-evoked EPSCs. Increased [K+]o (5{\textendash}10 mm) in the superfusion, producing modest depolarizations, consistently increased mEPSC frequency; an increase suppressed by mibefradil but not by HVA Ca2+ channel antagonists. Together these observations indicate that different Ca2+ channels are important for evoked EPSCs and mEPSCs in spinal laminae I and II and implicate a low-threshold type of Ca2+ channel in generation of mEPSCs.}, issn = {0270-6474}, URL = {https://www.jneurosci.org/content/18/21/8740}, eprint = {https://www.jneurosci.org/content/18/21/8740.full.pdf}, journal = {Journal of Neuroscience} }