Zeilhofer H U, Müller T H, Swandulla D
Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität Erlangen-Nürnberg, Universitätsstrasse 22, D-91054 Erlangen, Germany.
Pflugers Arch. 1996 Jun;432(2):248-57. doi: 10.1007/s004240050131.
The contribution of L-, N-, P- and Q-type Ca2+ channels to excitatory and inhibitory synaptic transmission and to whole-cell Ba2+ currents through Ca2+ channels (Ba2+ currents) was investigated in rat hypothalamic neurons grown in dissociated cell culture. Excitatory and inhibitory postsynaptic currents (EPSCs and IPSCs) were evoked by stimulating individual neurons under whole-cell patch-clamp conditions. The different types of high-voltage-activated (HVA) Ca2+ channels were identified using nifedipine, omega-Conus geographus toxin VIA (omega-CTx GVIA), omega-Agelenopsis aperta toxin IVA (omega-Aga IVA), and omega-Conus magus toxin VIIC (omega-CTx MVIIC). N-, but not P- or Q-type Ca2+ channels contributed to excitatory as well as inhibitory synaptic transmission together with Ca2+ channels resistant to the aforementioned Ca2+ channel blockers (resistant Ca2+ channels). Reduction of postsynaptic current (PSC) amplitudes by N-type Ca2+ channel blockers was significantly stronger for IPSCs than for EPSCs. In most neurons whole-cell Ba2+ currents were carried by L-type Ca2+ channels and by at least two other Ca2+ channel types, one of which is probably of the Q-type and the others are resistant Ca2+ channels. These results indicate a different contribution of the various Ca2+ channel types to excitatory and inhibitory synaptic transmission and to whole-cell currents in these neurons and suggest different functional roles for the distinct Ca2+ channel types.
在解离细胞培养中生长的大鼠下丘脑神经元中，研究了L型、N型、P型和Q型Ca2+通道对兴奋性和抑制性突触传递以及通过Ca2+通道的全细胞Ba2+电流（Ba2+电流）的贡献。在全细胞膜片钳条件下刺激单个神经元，诱发兴奋性和抑制性突触后电流（EPSC和IPSC）。使用硝苯地平、地纹芋螺毒素VIA（ω-CTx GVIA）、穴居狼蛛毒素IVA（ω-Aga IVA）和大子弹芋螺毒素VIIC（ω-CTx MVIIC）鉴定不同类型的高电压激活（HVA）Ca2+通道。N型而非P型或Q型Ca2+通道与对上述Ca2+通道阻滞剂有抗性的Ca2+通道（抗性Ca2+通道）一起，对兴奋性和抑制性突触传递均有贡献。N型Ca2+通道阻滞剂对IPSC的突触后电流（PSC）幅度的降低作用比对EPSC的作用明显更强。在大多数神经元中，全细胞Ba2+电流由L型Ca2+通道和至少两种其他Ca2+通道类型携带，其中一种可能是Q型，其他是抗性Ca2+通道。这些结果表明，各种Ca2+通道类型对这些神经元的兴奋性和抑制性突触传递以及全细胞电流有不同的贡献，并提示不同Ca2+通道类型具有不同的功能作用。
