Wada A, Yashima N, Izumi F, Kobayashi H, Yanagihara N
Neurosci Lett. 1984 Jun 1;47(1):75-80. doi: 10.1016/0304-3940(84)90389-6.
The role of sodium (Na) in stimulus-secretion coupling of adrenal medulla was investigated in primary culture of bovine adrenal medulla cells. In Na-free medium, the secretion of catecholamines and influx of 45Ca induced by carbachol were decreased to 30% and 18% of control responses, respectively. Carbachol induced secretion of catecholamines and influx of 45Ca were not inhibited by tetrodotoxin, a highly selective blocker of voltage dependent Na-channels. Carbachol caused a rapid influx of 22Na which was inhibited by hexamethonium but not by tetrodotoxin. Nicotine but not muscarine could be a substitute for carbachol and caused catecholamine secretion, 45Ca influx 22Na influx. Veratridine caused continuous secretion of catecholamines and influxes of 45Ca and 22Na which were blocked by tetrodotoxin. These results indicate that in cultured bovine adrenal medulla cells, stimulation of nicotinic receptor causes the influx of Na through receptor-mediated Na-channels but not through voltage-dependent Na-channels, and that influxed Na may facilitate the influx of Ca which triggers the secretory process. The sodium ion seems to be involved in the stimulus-secretion coupling evoked by physiological secretagogue in adrenal medulla.
在牛肾上腺髓质细胞原代培养中研究了钠（Na）在肾上腺髓质刺激 - 分泌偶联中的作用。在无钠培养基中，卡巴胆碱诱导的儿茶酚胺分泌和45Ca内流分别降至对照反应的30%和18%。卡巴胆碱诱导的儿茶酚胺分泌和45Ca内流不受河豚毒素（一种电压依赖性钠通道的高度选择性阻滞剂）的抑制。卡巴胆碱引起22Na快速内流，六甲铵可抑制该内流，但河豚毒素不能。尼古丁而非毒蕈碱可替代卡巴胆碱并引起儿茶酚胺分泌、45Ca内流和22Na内流。藜芦碱引起儿茶酚胺持续分泌以及45Ca和22Na内流，这些均被河豚毒素阻断。这些结果表明，在培养的牛肾上腺髓质细胞中，烟碱受体的刺激通过受体介导的钠通道而非电压依赖性钠通道引起Na内流，并且内流的Na可能促进Ca内流，从而触发分泌过程。钠离子似乎参与了肾上腺髓质中生理性促分泌剂诱发的刺激 - 分泌偶联。
