The effects of Ecliptae Herba on ion channels of single neuron employing nystatin perforated patch clamp under voltage clamp were investigated and the following results were obtained.
1. The magnitudes of ion currents caused by various concentrations of Ecliptae Herba compared to 10 exp (-5)M of glycine used as the control were recorded. As the result Ecliptae Herba, in neuron, recorded the ion currents depending on concentrations. With 10.0㎎/㎖ of Ecliptae Herba, the ion current equivalent to 206.30±32.70% of the ion current by the control was recorded and it was the maximal concentration.
2. Considered the ion current recorded by 3㎎/㎖ of Ecliptae Herba as the control, the following data were obtained.
1) 10^-4M of bicuculline suppressed the ion current of the control by 77.23±2.71%.
2) 10^-4M of tubocurarine repressed the ion current of the control by 57.86±3.44%.
3) When both bicuculline and tubocurarine were applied, the ion current of Ecliptae Herba was suppressed by 70.78±3.80%.
Therefore, the ion current recorded from Ecliptae Herba is due mainly to the excitation of GABA_A receptor rather than the excitation of acetylcholine receptor.
3. Taken the ion current recorded from 1㎎/㎖ of Ecliptae Herba as the control, the following data were obtained.
1) D-AP5, a NMDA receptor antagonist, suppressed the ion current of the control by 12.12±3.10%.
2) CNQX, a non-NMDA receptor antagonist repressed the ion current of the control by 18.23±3.92%.
This experiment had shown that Ecliptae Herba does not greatly affect glutamate receptors.
4. The magnitudes of th ion currents, when 0.5㎎/㎖ of Ecliptae Herba was applied on single neuron in two minutes interval, was reduced as the experiment proceeded. When a mixed solution of 10^-5M of forskolin, 10^-4M of IBMX and 10^-5M of dibutyl cAMP was applied for thirty seconds, the ion currents caused by Ecliptae Herba were reduced more sharply than the control. Hence, this experiment presented the fact that the magnitude of ion current of Ecliptae Herba was decreased as the concentration of cAMP in the neuron increased.
5. When Ecliptae Herba was pre-treated by 10^-7M of staurosporin for thirty seconds, the ion current was reduced more dully than the control. Therefore, in neurone, the ion channels activated by Ecliptae Herba were inhibited by cAMP-protein kinase.
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