Functional organization of chromaffin cells and cholinergic synaptic transmission in rat adrenal medulla.
Functional organization of chromaffin cells and cholinergic synaptic transmission in rat adrenal medulla.
复制标题
大鼠肾上腺髓质嗜铬细胞的功能组织和胆碱能突触传递。
DOI：
10.2170/jjphysiol.47.449
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Toshio Iijima
中科院分区：
文献类型：
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作者：
R. Kajiwara;Olav Sand;Yoshiaki Kidokoro;M. Barish;Toshio Iijima
在大鼠肾上腺髓质切片上用光学方法记录嗜铬细胞的膜去极化，用全细胞膜片钳方法记录细胞膜电位和电流。内脏神经纤维的刺激引起了跨切片的电活动的不连续传播。直径约80微米的细胞簇同时被激发，表明肾上腺髓质被组织成具有共同神经支配的离散细胞复合体。原位嗜铬细胞的电特性与以往报道的培养细胞一致。一部分记录的细胞显示兴奋性突触后电流（EPSC）的0.2-1 nA的刺激突触前神经纤维后。EPSC被六烃季铵阻断，表明烟碱型ACh受体参与其中。EPSC的衰减相是很好的拟合的两个指数与时间常数为6.3和57.3毫秒的总和。快分量的相对振幅为84.1%。这两个指数可能反映了突触前释放ACh激活快和慢时间常数ACh受体通道。在低[Ca ~（2+）]盐水中EPSC振幅直方图上有多个峰，第一个峰在37 pA处。为了解决量子大小，微型EPSC记录在河豚毒素含有高-[K+]的解决方案。微型EPSC振幅直方图也是多峰的，第一个峰在25 pA，这可能代表了突触的量子大小。第二个和第三个峰值是第一个峰值的整数倍。
Optical recordings of membrane depolarization and whole-cell patch-clamp recordings of membrane potentials and currents were obtained from chromaffin cells in slices of rat adrenal medulla. The stimulation of splanchnic nerve fibers caused a discontinuous spread of electrical activity across the slice. Cells in clusters with diameters of about 80 microns were excited simultaneously, suggesting that the adrenal medulla is organized into descrete cell complexes with common innervation. The electrical properties of chromaffin cells in situ were in agreement with previous reports on cultured cells. A fraction of the recorded cells displayed excitatory postsynaptic currents (EPSCs) of 0.2-1 nA upon the stimulation of presynaptic nerve fibers. The EPSC was blocked by hexamethonium, suggesting that nicotinic ACh receptors were involved. The decay phase of the EPSC was well fit by the sum of two exponentials with time constants of 6.3 and 57.3 ms. The relative amplitude of the fast component was 84.1%. These two exponentials may reflect activation of both fast and slow time-constant ACh receptor channels by presynaptic release of ACh. There were multiple peaks in the EPSC amplitude histograms in low-[Ca2+] saline, the first peak was at 37 pA. To resolve the quantal size, miniature EPSCs were recorded in a tetrodotoxin-containing high-[K+] solution. The miniature EPSC amplitude histograms were also multimodal with the first peak at 25 pA, which probably represents the quantal size of the synapse. The second and third peaks were at the integer multiples of the first one.