Chromaffin cells as a neuron model

大部分大鼠肾上腺染色质细胞（约60%）显示自发的[Ca^<2+>]_c振荡和自发动作电位。GABA （γ -氨基丁酸）以可逆方式抑制自发的[Ca^<2+>]_c振荡。GABA的作用由GABA_A受体模拟，可能增加氯离子电导（Kanno）。相较于革兰霉素，孢毒素更适合用于SBFI的体内校准，以测量SBFI处理的培养猪肾上腺染色质细胞内Na^+浓度（[Na^+]i） （Nakazato）。Yanagihara等人从牛肾上腺髓细胞中分离出一种新的Ca^<2+>/钙调素依赖性蛋白激酶II的内源性底物。蛋白测序和免疫印迹显示新的底物可能是嗜铬粒蛋白A （Yanagihara）。蛋白激酶C （PKC）可能参与组胺激活的信号转导，从而下调大鼠肾上腺嗜铬细胞的受体/ g蛋白系统（Warashina）。Kumakura等人研究了针对synaptotagmin C2A和C2B结构域的抗体的作用，以及肌醇高聚磷酸酯系列（IHPS）对钙<2+>-诱发的儿茶酚胺（Ca）从地地黄素渗透肾上腺染色质细胞释放的影响。IHPS与C2B结构域的结合可能会使停靠或启动的囊泡在细胞内Ca^<2+>的静息水平下远离自发融合（Kumakura）。利用共聚焦激光显微镜和在细胞外培养基中加入阴离子染料（HPTS），研究了培养的牛肾上腺染色质细胞的内吞作用和胞外作用。一个大的空泡空间通常在单个颗粒的胞外反应后立即形成，被证实是质膜的内陷（Terakawa）。

A large fraction of rat adrenal chromaffin cells (about 60%) shows spontaneous [Ca^<2+>]_c oscillations and spontaneous action potentials. GABA (gamma-aminobutyricacid) inhibited the spontaneous [Ca^<2+>]_c oscillations in a reversible manner. The effect of GABA was mimicked by the GABA_A receptor, which may increase chloride ion conductance (Kanno). Palytoxin is much more proper than gramicidin for in vivo calibration of SBFI to measure intracellular Na^+ concentration ([Na^+]i) in SBFI-treated cultured porcine adrenal chromaffin cells (Nakazato). Yanagihara et al. isolated a new endogenoussubstrate for Ca^<2+>/calmodulin-dependent protein kinase II from bovine adrenal medullary cells. Protein sequencing and immunoblotting revealed that the new substrate may be chromogranin A (Yanagihara). Protein kinase C (PKC) may be involved in a signal transductionactivated by histamine, which may down-regulate receptor/G-protein system in rat adrenal chromaffincells (Warashina). Kumakura et al. have studied the effects of antibodies against C2A and C2B domains ofsynaptotagmin and the effects of inositol high-polyphosphate series (IHPS) on Ca^<2+>-evoked catecholamine (CA) release from digitonin-permeabilized adrenal chromaffin cells. IHPS binding to the C2B domain might keep the docked or primed vesicles away from spontaneous fusion at resting level of intracellular Ca^<2+> (Kumakura). By using a confocal laser microscope and an anionic dye (HPTS) added to extracellularmedium, endocytosis associated with exocytosis was studied in cultured bovine adrenal chromaffin cells. Alarge vacuolar space often formed immediately after an exocytotic response of a single granule was confirmed to be an invagination of the plasm membrane (Terakawa).