SIMULTANEOUS AMPEROMETRIC MEASUREMENT OF ASCORBATE AND CATECHOLAMINE SECRETION FROM INDIVIDUAL BOVINE ADRENAL-MEDULLARY CELLS
SIMULTANEOUS AMPEROMETRIC MEASUREMENT OF ASCORBATE AND CATECHOLAMINE SECRETION FROM INDIVIDUAL BOVINE ADRENAL-MEDULLARY CELLS
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DOI：
10.1021/ac00111a017
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发表时间：
1995-08-01
影响因子：
7.4
通讯作者：
WIGHTMAN, RM
中科院分区：
文献类型：
--
作者：
CAHILL, PS;WIGHTMAN, RM
已通过碳纤维微电极的电流分析法检测到单个牛肾上腺髓质细胞分泌的抗坏血酸和儿茶酚胺。使用两个碳纤维电极。一个是斜角的，该电极的伏安图显示抗坏血酸和儿茶酚胺的响应重叠。另一个被斜切并进行电化学氧化，以将抗坏血酸氧化波转移到比儿茶酚胺更负的电位。因此，在相对于SSCE为0.05V的施加电势下，抗坏血酸在处理过的电极处被选择性氧化，并且在未处理的电极上在0.65V的施加电势下儿茶酚胺和抗坏血酸都被氧化。 K+、尼古丁和洋地黄皂苷刺激细胞的胞吐释放。尼古丁和 K+ 使细胞膜去极化并引起囊泡释放。洋地黄皂苷是一种清洁剂，可与质膜中的胆固醇发生反应并导致孔的形成。来自单个细胞的抗坏血酸流出可由洋地黄皂苷诱导，但不能由 K+ 或尼古丁诱导，并且观察为半峰全宽为 4 s 的单峰。相反，当细胞暴露于洋地黄皂苷、K+或尼古丁时，观察到儿茶酚胺释放为许多快速、连续的电流尖峰。这两种不同类型的释放表明抗坏血酸和儿茶酚胺是从两个不同的细胞区室中释放的。洋地黄皂苷诱导的抗坏血酸释放的钙独立性提供了额外的证据，表明抗坏血酸是通过非胞吐过程释放的。
Secretion of ascorbate and catecholamines from single bovine adrenal medullary cells has been detected with amperometry at carbon-fiber microelectrodes. Two carbon-fiber electrodes were employed. One was beveled, and voltammograms at this electrode showed overlap of the responses for ascorbate and the catecholamines. The other was beveled and electrochemically oxidized to shift the ascorbate oxidation wave to potentials more negative than that of the catecholamines. Thus, at an applied potential of 0.05 V vs SSCE, ascorbate was selectively oxidized at the treated electrode and both catecholamines and ascorbate were oxidized at an applied potential of 0.65 V at the untreated electrode. Exocytotic release from the cell was stimulated with K+, nicotine, and digitonin. Nicotine and K+ depolarize the cell membrane and elicit vesicular release. Digitonin is a detergent th;at reacts with cholesterol in the plasma membrane and causes the formation of pores. Ascorbate efflux from individual cells could be induced by digitonin but not by K+ or nicotine and was observed as a single peak with a full width at half-maximum of 4 s. In contrast, catecholamine release was observed as many rapid, sequential current spikes when the cell was exposed to either digitonin, K+, or nicotine, The two different types of release show that ascorbate and catecholamines are being released from two different cellular compartments, The calcium independence of the digitonin-induced ascorbate release provides additional evidence that ascorbate is released by a nonexocytotic process.