The Effect Of Vinpocetine On Whole-Cell Ion Channel Currents In Rat Hippocampal CA3 Pyramidal Neurons

[Objective]The characteristics of the ion channels on cell membrane are direct related to the change of the neurons' functions. The present study explores the influence of Vinpocetine on whole cell currents, whole cell potassium currents, transient outward potassium currents and whole cell calcium currents of the neurons in neonate rat hippocampus CA3 area. The aim is to give experimental support to Vinpocetine's neuroprotective effect on ion channels level.[Methods]Neurons in hippocampus CA3 area of neonate rat were disassociated acutely with enzymatic digestion combined with mechanical driving. We recorded the whole cell currents, whole cell potassium currents, transient outward potassium currents and whole cell calcium currents of neurons with the patch clamp techniques under both normal condition and the activation of Vinpocetine. The kinetic character of the transient outward potassium currents and whole cell calcium currents were analyzed with Clampfit9.0 and Igor5.01.[Results]Neonate rat hippocampal CA3 pyramidal neurons dissociated acutely were in good conditions. Body and axon of the neurons can be observed clearly. The boundary of the neurons has good refractive index and the neurons can adherence quickly. And the experiments results were as follows:1. The whole cell currents we recorded include two components: inward currents and outward currents. The inward currents were activated quickly and quickly inactivated. The outward currents were activated quickly but slowly inactivated. After the addition of Vinpocetine, the whole cell currents diminished quickly and trended stabilization 5 minutes later. The effects have does-dependent properties and time-dependent properties. 2. The whole cell potassium currents have the typical characteristics and are activated at about -30mV, increased gradually with the increase of stimulus voltage pulse. Vinpocetine with high concentrations greatly inhibited the whole cell potassium currents. The whole cell potassium currents decreased 74% with Vinpocetine compared with 32.1% without Vinpocetine.3. The transient outward potassium currents activated quickly at about -20mV and quickly inactivated. The effects of Vinpocetine on transient outward potassium currents were does-dependent. And the inactivation kinetic curves were left moved in the effect of Vinpocetine.4. The whole cell calcium currents are activated at about -40mV and reach the peaks at 0mV. And the whole cell calcium currents are inactivated slowly. Vinpocetine inhibited the whole cell calcium currents and the effects were does-dependent and time-dependent. The inactivation kinetic curves of the whole cell calcium currents were down moved in the effects of Vinpocetine with the invariable starting point.[Conclusions]The effects of Vinpocetine on pyramidal neurons in neonate rat hippocampal CA3 area were investigated and the conclusions were shown as follows:1. Vinpocetine inhibited the whole cell currents. The effects were time -dependent and does-dependent.2. Vinpocetine inhibited the whole cell potassium currents. The effects were time-dependent and does-dependent.3. Vinpocetine enhanced the transient outward potassium currents. The effects were does-dependent and the inactivation kinetic curves were left moved in the effect of Vinpocetine. It suggested that Vinpocetine may have neuroprotective effect on neurons by enhancing the transient outward potassium currents.4. Vinpocetine inhibited the whole cell calcium currents. The effects were time-dependent and does-dependent, and the inactivation kinetic curves were down moved in the effect of Vinpocetine. And we assume that Vinpocetine in high concentrations may protect nervous systems by inhibiting calcium channel currents.5. Vinpocetine has negligible effects on ion channels in neurons. Thevalue of Vinpocetine as ion channel drugs still needs more empirical studies and theoretical supports.