WHOLE-CELL CLAMP STUDY OF XENOPUS EMBRYONIC CHOLINERGIC NEURONS

Whole-cell clamped myoballs are placed into direct visible contact with the growth cones of isolated neurons in embryonic Xenopus culture to serve as probe of acetylchollne (AcCHo) release in order to determine whether these neurons are cholinergic or not. Using a GQ-seal, whole-cell recording method, the electrophysiological properties of these identified cholinergic neurons are studied. It is found that these embryonic neurons, like adult frog motor neurons, exhibit repetitive firings in a certain embryonic developing stage. A development of repetitive firings is observed simultaneously. Tracing the development of one neuron, we find that the development of repetitive firing is completed at the 48th h after fertilization. Tetrodotoxin (TTX) which blocks Na~+ channels can abolish all firings; and tetraethyl ammonium chloride (TEA), the blocker of K~+ channels, reverses this development, i. e. it makes the repetitive firings disappear again. These data show that the nature of the development of repetiti     

爪蟾胚胎胆碱能神经元的全细胞箝制研究

将全细胞箝制的肌细胞移到神经突上去探测乙酰胆碱(Ach)的释放,从而标定出该神经元是否是胆碱能神经元。使用单通道技术中的全细胞箝制法研究了胚胎胆碱能神经元的电生理学特性,发现它们在发育的特定阶段象成体蛙运动神经元一样具有重复发放的特性。河豚毒素(TTX)能消除所有的发放活动;而四乙基乙二胺(TEA)能升高阈值,延缓复极化过程,减少重复发放数目。追踪同一个神经元的发育过程表明,重复发放约在卵受精后48h完成发育。