Coriaria lactone increased the intracellular level of calcium through the voltage-gated calcium channels in rat hippocampal neurons.

ABSTRACT

To investigate the effects of Coriaria Lactone (CL), an epileptogenic substance, on intracellular levels of calcium ([Ca(2+)](i)) and physiological properties of voltage-gated calcium channels (VGCCs). Ratiometric calcium imaging using Fura Red and whole-cell voltage patch-clamp technique were explored on freshly isolated rat hippocampal neurons exposed to CL. Coriaria Lactone increased [Ca(2+)](i) from 118 +/- 21 to 440 +/- 35 nM; VGCCs and calcium influx through NMDA receptor served as the main routes of entry. Coriaria Lactone could enhance both Low voltage activated (LVA) and High voltage activated calcium currents in a concentration-dependent way, and its effect on LVA current was more potent (about 60%). The increased calcium currents were accompanied by the shift of voltage-dependent steady-state inactivation to more positive potentials. These effects of CL, especially its impact on LVA current, could activate different calcium-dependent signaling pathways, and influence cellular excitable properties as well, which might play an important role in CL's epileptogenic process.