乙酰胆碱减小猫外膝体中继细胞低阈值T—型钙电导

ACETYLCHOLINE DECREASES LOW THRESHOLD T-TYPE CALCIUM CONDUCTANCE OF RELAY CELLS IN THE CAT'S LATERAL GENICULATE NUCLEUS

在离体猫丘脑脑片上观察了乙酰胆碱对外膝体中继神经元膜的低阈值T-型钙电导的影响。电流箝位和电压箝位实验结果都显示：将膜电位箝制到给药前的对照水平，排除了乙酰胆碱的去极化作用后，大多数（82％）外膝体神经元的低阈值钙电导仍然被乙酰胆碱所抑制。说明这种抑制作用独立于乙酰胆碱引起的膜电位变化，而是对低阈值T-型钙通道的直接作用。

The effect of acetylcholine (ACh) on the low threshold T-type Ca2+ conductanceof relay cells in the cat lateral geniculate nucleus (LGN) was studied using in thee thalamic slices. Results from both current-clamp and voltage-clamp experimentS showed thatthe low threshold Ca2+ conductance was inhibited by ACh in most (82%) of the LGNneurons tested, even when the membrane potential was clamped to the control level.This inhibitory effect was independent of the changes in membrane potential by ACh.Therefore, ACh might exert a direct action on low threshold Ca2+ channels.