Effect of volatile anesthetics on Cultured Neuron of Lymnaea stagnalis

全身麻醉药影响神经系统细胞间通讯的细胞和突触机制仍不清楚。在细胞培养中，在两个功能良好的神经元-右足1(RPeD1)和内脏背侧4(VD4)的体细胞之间重建了抑制性突触。临床相关浓度的七氟醚(1-4%)对突触传递和胞体-胞体配对细胞的固有膜特性的影响进行了检测。七氟醚(4%)可完全可逆地阻断RPeD1诱导的VD4突触后抑制电位。七氟醚还抑制RPeD1和VD4细胞的动作电位。为了阐明临床相关浓度的挥发性麻醉药产生的[Ca^&lt；2+&gt；]i的机制，我们用培养的Lymna stanalis神经元同时测定了[Ca^&lt；2+&gt；]i和细胞内记录。从钉螺中分离出RPeD1神经元。用Fura-2荧光分光光度法检测麻醉诱导的[Ca~(2+)&gt；]i变化。对1%和4%的浓度进行了评价。为了忽略动作电位，我们将膜电位超极化10 mV，并重复相同的测量。七氟醚1%使RPeD1神经元[Ca~(2+)]i从325±7(nM±SD)增加到350±8，动作电位数增加到30±12(/min±SD)。七氟醚浓度为4%时，[Ca~(2+)]i先由330±41增至380±35，再增加至50±5，其中[Ca~(2+)]i逐渐降低，动作电位迅速降至0。未激活的七氟醚1%可使[Ca~(2+)]i由320±32升至332±32，4%则无变化。结果表明，低浓度的七氟醚在激活和不激活Lymneea stagnaris的RPeD_1神经元的情况下均使[Ca~(2+)&gt；]i升高，而高浓度的七氟醚使[Ca~(2+)&lt；2+&gt；]i从增加的水平增加。

The cellular and synaptic mechanisms by which general anesthetics affect cell-cell communications in the nervous system remain poorly defined. Inhibitory synapses were reconstructed in cell culture, between the somata of two functionally well-characterized neurons, right pedal 1 (RPeD1) and visceral dorsal 4 (VD4). Clinically relevant concentrations of sevoflurane (1-4%) were tested for their effects on synaptic transmission and the intrinsic membrane properties of soma-soma paired cells. RPeD1-induced inhibitory postosynaptic potentials in VD4 were completely and reversibly blocked by sevoflurane (4%). Sevoflurane also suppressed action potentials in both RPeD1 and VD4 cells.To clear the mechanism in [Ca^<2+>]i produced by clinically relevant concentration of volatile anesthetics, we measured [Ca^<2+>]i and intracellular recording simultaneously using a cultured neuron of Lymnaea stagnalis. The RPeD1 neurons were dissected from snails. Anesthetic-induced change in [Ca^<2+>]i were measured with fura-2 fluorescence spectroscopy. The concentration of 1% and 4% were evaluated. To neglect the action potential, we hyperpolarized the membrane potential 10mV and the same measurements were repeated. Sevoflurane 1% increased [Ca^<2+>]i from 325±7 (nM±SD) to 350±8, with the increasing of the number of action potentials to 30±12 (/min±SD) in RPeD1 neurons. Sevoflurane 4%, first increased [Ca^<2+>]i from 330±41 to 380±35 with the increasing to 50±5, in which [Ca^<2+>]i decreased gradually and the number of action potentials decreased to 0 rapidly. Sevoflurane, without activation, increase [Ca2+]i from 320±32 to 332±32 in 1%, and no change from 332±19 to 341±17 in 4%. We concluded that low concentration of sevoflurane increase [Ca^<2+>]i both with and without the activation of the RPeD1 neuron of Lymnaea stagnalis, while high concentration of sevoflurane d [Ca^<2+>]i from the increasing level.