Intracellular Ca2+-dependent protein kinase C activation mimics delayed effects of thyrotropin-releasing hormone on clonal pituitary cell excitability.
Intracellular Ca2+-dependent protein kinase C activation mimics delayed effects of thyrotropin-releasing hormone on clonal pituitary cell excitability.
复制标题
细胞内 Ca2 依赖性蛋白激酶 C 激活模拟促甲状腺激素释放激素对克隆垂体细胞兴奋性的延迟影响。
作者：
B. Dufy;S. Jaken;J. Barker
对克隆垂体腺(GH)细胞转导TRH信号的第二信使通路的生化和分光光度研究表明，TRH可引起肌醇磷脂的快速转换和胞浆内钙离子的变化，以及蛋白激酶C(PKC)的激活和PRL的分泌。在这里，我们使用经典微电极和当代膜片管记录技术在电流钳条件下比较了TRH受体偶联刺激和直接激活PKC对GH3/B6细胞兴奋性的影响。在高阻微电极上，TRH引起了一系列复杂的膜特性变化，包括最初20-30 mV的超极化，膜电导持续不到一分钟的增加，随后几分钟的低幅度波动和动作电位活动叠加在输入电阻的适度增加上。活性佛波酯引起缓慢发展的约5 mV的超极化和输入电阻的适度增加，随后是几分钟的低幅度波动和自发动作电位活动。在全细胞模式的斑贴记录过程中，多肽和佛波酯引起的兴奋性变化都减弱或完全消失。克隆的稀释水溶物恢复了电反应的不同阶段。用含有PKC和至少50 nM Ca~(2+)的胞内电解液透析细胞，TRH或佛波酯均可引起细胞低幅度波动和动作电位活跃期。这些结果表明，在克隆的垂体细胞中，TRH激活的磷脂酰肌醇/PKC通路对细胞的兴奋性具有电可测效应，这有助于解释TRH对电活动的作用。
Biochemical and spectrophotometric studies of second messenger pathways transducing TRH signals in clonal pituitary (GH) cells have shown that TRH induces rapid turnover of phosphoinositides and changes in cytoplasmic Ca2+ as well as activation of protein kinase C (PKC) and secretion of PRL. Here we have used classical microelectrode and contemporary patch pipette recording techniques under current-clamp conditions to compare the effects of TRH receptor-coupled stimulation with direct activation of PKC on the excitability of GH3/B6 cells. With high resistance microelectrodes TRH induced a complex sequence of changes in membrane properties consisting of an initial 20- to 30-mV hyperpolarization associated with an increase in membrane conductance lasting less than a minute, followed by several minutes of low amplitude fluctuations and action potential activity superimposed on a modest increase in input resistance. Active phorbol ester induced a slowly developing hyperpolarization of about 5 mV and a modest increase in input resistance, followed by several minutes of low amplitude fluctuations and spontaneous action potential activity. Both the peptide- and phorbol ester-evoked changes in excitability were attenuated or completely lost during patch recordings in the whole cell mode. Dilute aqueous lysates of the clone restored various phases of the electrical response. The low amplitude fluctuations and action potential activity phase could be induced by either TRH or phorbol ester if the cells were dialyzed with intracellular electrolyte containing PKC and at least 50 nM Ca2+. These results demonstrate that the phosphoinositide/PKC circuit activated by TRH in clonal pituitary cells has electrically detectable effects on cell excitability, and these help to explain TRH's actions on electrical activity.
克隆垂体细胞中促甲状腺素释放激素对 K 通道的双重调节。
DOI：
10.1073/pnas.82.12.4282
发表时间：
1985
影响因子：
11.1
作者：
Dubinsky,JM;Oxford,GS
通讯作者：
Oxford,GS
促甲状腺激素释放激素刺激垂体激素分泌的机制。
影响因子：
18.2
作者：
Gershengorn,MC
通讯作者：
Gershengorn,MC