Nakagawa H, Yanagihara N, Izumi F, Wada A, Kimura A
Department of Health Science, Faculty of Integrated Arts and Sciences, University of Tokushima, Japan.
Biochem Pharmacol. 1992 Nov 3;44(9):1779-85. doi: 10.1016/0006-2952(92)90072-q.
We previously reported the partial purification and characterization of a toxic substance (sea urchin toxin) isolated from the pedicellariae of the sea urchin Toxopneustes pileolus (Nakagawa and Kimura, Jpn J Pharmacol 32: 966-968, 1982). In the present study, we examined the effect of sea urchin toxin on catecholamine secretion and synthesis in cultured bovine adrenal medullary cells. Sea urchin toxin inhibited the secretion of catecholamines stimulated by carbachol and nicotine but not by veratridine or a high concentration of K+. The toxin inhibited the carbachol-evoked influx of 22Na+ and 45Ca2+ at concentrations similar to those for catecholamine secretion. The inhibition of catecholamine secretion by sea urchin toxin was not overcome by increasing the concentration of carbachol. Preincubation of cells with the toxin caused a time-dependent inhibition in the secretion stimulated by carbachol even when the toxin was removed from the incubation medium. The toxin suppressed catecholamine synthesis and tyrosine hydroxylase activity in carbachol-stimulated cells. In addition, sea urchin toxin inhibited [3H]phencyclidine binding to adrenal medullary cells whereas it did not alter cyclic GMP accumulation caused by muscarine. Further purified fractions from sea urchin toxin by concanavalin A affinity column chromatography also inhibited carbachol-evoked secretion of catecholamines. These results suggest that sea urchin toxin inhibits carbachol-enhanced secretion and synthesis of catecholamines by suppression of nicotinic acetylcholine receptor-mediated Na+ influx and subsequent Ca2+ influx in cultured adrenal medullary cells.
我们之前报道过从毒棘海胆（Toxopneustes pileolus）的叉棘中分离出一种有毒物质（海胆毒素）的部分纯化及特性分析（中川和木村，《日本药理学杂志》32: 966 - 968, 1982）。在本研究中，我们检测了海胆毒素对培养的牛肾上腺髓质细胞中儿茶酚胺分泌及合成的影响。海胆毒素抑制了由卡巴胆碱和尼古丁刺激引起的儿茶酚胺分泌，但对藜芦碱或高浓度钾离子刺激引起的分泌没有抑制作用。该毒素在与儿茶酚胺分泌相似的浓度下，抑制了卡巴胆碱诱发的22Na+和45Ca2+内流。增加卡巴胆碱的浓度并不能克服海胆毒素对儿茶酚胺分泌的抑制作用。即使将毒素从孵育培养基中去除，用毒素对细胞进行预孵育也会导致卡巴胆碱刺激的分泌出现时间依赖性抑制。该毒素抑制了卡巴胆碱刺激的细胞中儿茶酚胺的合成及酪氨酸羟化酶的活性。此外，海胆毒素抑制了[3H]苯环己哌啶与肾上腺髓质细胞的结合，而对毒蕈碱引起的环鸟苷酸积累没有影响。通过伴刀豆球蛋白A亲和柱层析对海胆毒素进一步纯化得到的组分也抑制了卡巴胆碱诱发的儿茶酚胺分泌。这些结果表明，海胆毒素通过抑制烟碱型乙酰胆碱受体介导的钠离子内流以及随后培养的肾上腺髓质细胞中的钙离子内流，来抑制卡巴胆碱增强的儿茶酚胺分泌及合成。
