培养大鼠颈上神经节细胞胆碱诱发电流的特征

目的　探讨培养大鼠颈上神经节神经元胆碱诱发电流的反应特征。方法　在培养的大鼠颈上交感节神经元上 ,以α7 nAChR选择性激动剂choline为工具药 ,通过喷射给药 ,采用膜片钳全细胞记录方式研究胆碱诱发电流的电生理学特征。结果　在培养的大鼠颈上交感节神经元上 ,喷射给予α7 nAChR选择性激动剂胆碱可诱发出一内向电流 ,其EC50 值为 8 2 5mmol·L-1,电流包含快、慢两种成分 ,并能被α7 nAChR选择性拮抗剂methyllycaconitine(MLA ,1μmol·L-1)以及α bungarotoxin(α Bgt,1μmol·L-1)明显抑制 ;间隔10、2 0s反复给予胆碱 (10mmol·L-1,1s)可导致诱发电流幅度明显下降 ,电流峰值分别下降为初始幅度的 33 4 %±6 3% (n =3)、32 7%± 5 5 % (n =3) ,持续给予胆碱 (10mmol·L-1,30s)亦可导致该诱发电流幅度明显下降 ,停止刺激后 3min诱发电流幅度可恢复为初始幅度的73 9%± 13 3% (n =10 )。结论　以胆碱激活培养的大鼠颈上交感节神经元α7型N受体 (α7 nAChR)可产生内向电流 ,该电流具有失敏特性

The characteristics of choline-evoked current in cultured rat superior cervical ganglia neurons

AIM To investigate the characteristics of choline evoked current in cultured rat superior cervical ganglia neurons. METHODS The Whole cell recording configuration of patch clamp technique was used to study the electrophysiological features of α 7 nAChR in cultured rat superior cervical ganglia neurons by rapid application of choline, a selective agonist of α 7 nAChR, onto the soma of the neurons. RESULTS An inward current was elicited by rapid application of choline in cultured rat superior cervical ganglia neurons with an EC 50 of 8 25 mmol·L -1 ; The choline evoked current consisted of a fast and a slow component and could be significantly inhibited by methyllycaconitine (MLA, 1 μmol·L -1 ) and α bungarotoxin (α Bgt, 1 μmol·L -1 ) which were selective antagonists of α 7 nAChR; The amplitude of choline evoked current was decreased significantly to 33 4%±6 3%( n =3) or 32 7%±5 5% ( n =3) of its baseline level by repeated application of choline (10 mmol·L -1 ,1 s) at an interval of 10 or 20 seconds, respectively and the similar result was observed when application of choline (10 mmol·L -1 ) continuously for 30 seconds, while the amplitude of the current was recovered to 73 9%±13 3% ( n =10)of its initial value 3 minutes after the prolonged stimulation. CONCLUSIONS An inward current can be evoked through α 7 nAChR activated by choline in cultured rat superior cervical ganglia neurons and this current had characteristics of desensitization.