The Effects Of Volatile Oil Of Nardostachys Chinensis On Sodium Channel Of Isolated Ventricular Myocytes In Rat

OBJECTIVE: To investigate the effects of the volatile oil of Nardostachys chinensis with different dosages on sodium channel of isolated ventricular myocytes of rat.And the effects of the volatile oil of Nardostachys chinensis on I-V curve; activation cureve and inactivation curve were also investigated.METHODS: Ventricular myocytes were isolated enzymatically from rat which was sacrificed after anesthesia with pentobarbital, The heart was quickly removed and hung up a Langendorff apparatus and perfused initially with Ca²⁺ free Tyrode's solution for 5 minutes, then perfused digest enzyme solution for about 20 minutes at 37℃. As soon as the heart became softened, the ventricle was cut into nubs and blown with sucker in KB solution to obtain single cells. Only rod-shaped cells with smooth surfaces and cross-striations were selected for patch clamp. The tip resistance of the micro electrodes is ranging from 1.0³.0 MΩ.RESULTS:1. The volatile oil of Nardostachys chinensis reduced sodium current in a dose-dependent block. The concentration of volatile oil of chinensis at 1,3,5,10,100μg/g suppressed I_Na current which inhibition rate respectively was 8.0±2.9%,20.9±3.5%,53.9±7.8%,74.9±3.4%,94.7±3.6% (n=5,P<0.05)2. The concentration of volatile oil of Nardostachys chinensis at 5μg/g suppressed I_Na current remarkably. The average maximal peak current density is (-20.3±4.6)(pA/pF) after the exposure to drug vs control is (-44.7±10.3) (pA/pF). On the other hand. The volatile oil of Nardostachys chinensis did not shift the I-V curve.3. The activity curve have significant change by using the volatile oil of Nardostachys chinensis at 5μg/g. thier V1/2 is (-48.66±0.76)mV vs (-43.94±1.02) mV(n=5,P<0.05).4. The inactivation curve have significant change by using volatile oil of Nardostachys chinensis at 5μg/g concentration.their V1/2 is (-100.48±0.71)mV vs (-109.82±0.86)mV (n=5,P<0.05). CONCLUSION:1,The volatile oil of Nardostachys chinensis reduced the sodium channel current in a dose-dependent block.2,The volatile oil of Nardostachys chinensis lifted the I-V curve of I_Na without changing the threshold , peak and reversal potentials.3,The activation curve is shifted towards the depolarizing direction after exposuring to the drug.4,The inactivation curve is shifted toward to the hyperpolarizing direction after exposuring to the drug.