Marley P D, Livett B G
Neurosci Lett. 1987 Jun 1;77(1):81-6. doi: 10.1016/0304-3940(87)90611-2.
Cultured, bovine, adrenal medullary chromaffin cells have been used to study the secretion of adrenaline (A) and noradrenaline (NA) in response to two consecutive stimulation periods. Cells were first exposed to nicotine, then rapidly washed before being exposed to elevated K+ levels. Both A and NA cell types secreted their catecholamine in response to nicotine; however, NA cells secreted 3 times more of their catecholamine stores as did A cells. The NA cells were desensitized to stimulation by K+ if they had previously been exposed to nicotine. A cells, on the other hand, were up to twice as responsive to K+ stimulation after having been stimulated with nicotine, in spite of substantial depletion of their catecholamine stores. This sensitization of A cells to K+ was neither due to carryover of nicotine from the first stimulation period, nor to accumulation of calcium in the cells during the nicotinic stimulation. The results suggest that stimulus-secretion coupling or the exocytotic machinery in A and NA chromaffin cells is different. These differences may contribute to the ratio A:NA secreted from the adrenal medulla during stress.
培养的牛肾上腺髓质嗜铬细胞已被用于研究肾上腺素（A）和去甲肾上腺素（NA）在两个连续刺激期的分泌情况。细胞首先暴露于尼古丁，然后快速冲洗，再暴露于升高的钾离子水平。A 型和 NA 型细胞都会因尼古丁而分泌其儿茶酚胺；然而，NA 细胞分泌的儿茶酚胺储存量是 A 细胞的 3 倍。如果 NA 细胞先前已暴露于尼古丁，则它们对钾离子刺激会脱敏。另一方面，A 细胞在用尼古丁刺激后，尽管其儿茶酚胺储存大量耗尽，但对钾离子刺激的反应性高达两倍。A 细胞对钾离子的这种敏化既不是由于第一个刺激期尼古丁的残留，也不是由于烟碱刺激期间细胞内钙的积累。结果表明，A 型和 NA 型嗜铬细胞中的刺激-分泌偶联或胞吐机制是不同的。这些差异可能有助于解释应激期间肾上腺髓质分泌的 A:NA 比值。
