Taniguchi M, Kashiwayanagi M, Kurihara K
Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
J Neurosci. 1996 Feb 1;16(3):1239-46. doi: 10.1523/JNEUROSCI.16-03-01239.1996.
Turtle vomeronasal receptor neurons in slice preparations were studied using the patch-clamp technique in the whole-cell and cell-attached configurations. The mean resting potential was -48, and the response to an injected current step consisted of either a single spike or a train of spikes. An injected current of 3-30 pA was required to depolarize the neuron to spike threshold near -50 mV. Voltage-clamped vomeronasal receptor neurons displayed transient inward currents followed by sustained outward currents in response to depolarizing voltage steps. In cell-attached recordings, 10 microM forskolin added to the bath caused a transient increase of spike rate. Intracellular application of cAMP evoked ann inward current in a dose-dependent manner from the neurons voltage clamped at -70 mV; 0.1 mM cAMP was sufficient to elicit an inward current in the neurons. The magnitude of the response to cAMP reached a plateau at 1 mM with an average peak amplitude of 176 +/- 34 pA. Intracellular application of 1 mM cGMP also evoked an inward current with an average peak amplitude of 227 +/- 61 pA. The reversal potentials of the induced components were estimated to be 10 +/- 7 mV for cAMP and -4 +/- 16 mV for cGMP. The reversal potential of the cAMP-induced current in external Cl(-)-free solution was similar to that in normal Ringer's solution, suggesting that Cl- current is not significantly involved in the current. The present results represent the first evidence of cyclic nucleotide-activated conductance in the vomeronasal receptor membranes.
采用膜片钳技术的全细胞和细胞贴附模式，对脑片制备中的龟犁鼻器受体神经元进行了研究。平均静息电位为-48mV，对注入的电流阶跃的反应包括单个动作电位或一串动作电位。需要3-30pA的注入电流才能将神经元去极化至接近-50mV的动作电位阈值。电压钳制的犁鼻器受体神经元在去极化电压阶跃时表现出短暂的内向电流，随后是持续的外向电流。在细胞贴附记录中，向浴槽中加入10μM的福斯可林会导致动作电位频率短暂增加。在电压钳制于-70mV的神经元中，细胞内应用cAMP以剂量依赖的方式诱发内向电流；0.1mM的cAMP足以在神经元中诱发内向电流。对cAMP反应的幅度在1mM时达到平台期，平均峰值幅度为176±34pA。细胞内应用1mM的cGMP也诱发内向电流，平均峰值幅度为227±61pA。估计cAMP诱导成分的反转电位为10±7mV，cGMP诱导成分的反转电位为-4±16mV。在外部无Cl(-)溶液中，cAMP诱导电流的反转电位与正常林格氏溶液中的相似，这表明Cl-电流在该电流中没有显著作用。目前的结果首次证明了犁鼻器受体膜中存在环核苷酸激活的电导。
