Activation of protein kinase C increases Ca2+ sensitivity of secretory response of GH3 pituitary cells.
Activation of protein kinase C increases Ca2+ sensitivity of secretory response of GH3 pituitary cells.
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蛋白激酶 C 的激活增加 GH3 垂体细胞分泌反应的 Ca2+ 敏感性。
DOI：
10.1152/ajpcell.1993.264.4.c1020
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Hinkle,PM
中科院分区：
文献类型：
--
作者：
Haymes,AA;Hinkle,PM
研究了蛋白激酶 C 对 GH3 垂体细胞对 Ca2+ 的分泌反应的影响。用 100 nM 12-O-十四烷酰佛波醇 13-乙酸酯 (TPA) 激活蛋白激酶 C 40 分钟，可降低高 K+ 去极化刺激的细胞内游离钙浓度 ([Ca2+]i) 的上升，但不影响 50 mM K+ 刺激的催乳素分泌增加三倍。在通过添加 1,2-双(2-氨基苯氧基)-乙烷-N,N,N',N'-四乙酸 (BAPTA/AM) 的乙酰氧基甲酯来减少 [Ca2+]i 或添加或不添加 BAY K 8644 的高 K+ 来增加 [Ca2+]i 时获得的 [Ca2+]i 值范围内，测量对照细胞和 TPA 处理细胞的 [Ca2+]i 和催乳素释放。与对照细胞（约 270 nM）相比，用 TPA（约 160 nM）处理的细胞在 [Ca2+]i 浓度较低时出现半最大催乳素分泌，但高 [Ca2+]i 时的分泌率相同。蛋白激酶 C 激活后，GH3 细胞响应促甲状腺激素释放激素 (TRH) 的反应，也分泌更多的催乳素，尽管 TRH 引起的 Ca2+ 瞬变较小。荧光比率成像显示 GH3 细胞经历自发的 [Ca2+]i 振荡 (4-12/min)，TPA 几乎消除 [Ca2+]i 振荡并抑制去极化刺激的 [Ca2+]i 增加。这些结果表明，蛋白激酶 C 的激活增加了 GH3 细胞分泌反应的 Ca2+ 敏感性，导致典型细胞内 Ca2+ 浓度下的分泌速率增加两倍。
The effect of protein kinase C on the secretory response of GH3 pituitary cells to Ca2+ was investigated. Activation of protein kinase C with 100 nM 12-O-tetradecanoylphorbol 13-acetate (TPA) for 40 min reduced the rise in intracellular free calcium concentration ([Ca2+]i) stimulated by depolarization with high K+ but did not affect the threefold increase in prolactin secretion stimulated by 50 mM K+. Both [Ca2+]i and prolactin release were measured for control and TPA-treated cells over a range of [Ca2+]i values attained by adding the acetoxymethyl ester of 1,2-bis(2-aminophenoxy)-ethane -N,N,N',N'- tetraacetic acid (BAPTA/AM) to reduce [Ca2+]i or high K+ with or without BAY K 8644 to increase [Ca2+]i. Half-maximal prolactin secretion occurred at lower [Ca2+]i concentrations for cells treated with TPA (approximately 160 nM) than for control cells (approximately 270 nM), but the rate of secretion at high [Ca2+]i was the same. GH3 cells also secreted more prolactin in response to thyrotropin-releasing hormone (TRH) after protein kinase C activation, although TRH evoked a smaller Ca2+ transient. Fluorescence ratio imaging revealed that GH3 cells undergo spontaneous [Ca2+]i oscillations (4-12/min) and that TPA nearly abolishes [Ca2+]i oscillations as well as inhibits the increase in [Ca2+]i stimulated by depolarization. These results demonstrate that activation of protein kinase C increases the Ca2+ sensitivity of the secretory response in GH3 cells, causing up to a twofold increase in the rate of secretion at typical intracellular Ca2+ concentrations.