Gershengorn M C
J Biol Chem. 1980 Mar 10;255(5):1801-3.
Thyrotropin releasing hormone (TRH) and high extracellular K+ induce prolactin release from rat pituitary cells (GH3 cells) in culture. TRH, as well as high K+ (50 mM), was shown to increase 45Ca2+ efflux from these cells. The effects of TRH and high K+ on membrane polarization was determined indirectly using the lipophilic cation, triphenylmethyl phosphonium ion (TPMP+). The resting membrane potential of GH3 cells was -50 +/- 1.7 mV. TRH, which induced a marked increase in 45Ca2+ efflux and stimulated prolactin release, had no effect on membrane polarization measured simultaneously. High K+, which also increased 45Ca2+ efflux and prolactin release, depolarized the GH3 cell as evidenced by a marked increase in [3H]TPMP+ efflux. These results suggest that TRH and high K+ may act via different mechanisms to increase intracellular Ca2+ and stimulate prolactin release.
促甲状腺激素释放激素（TRH）和高细胞外钾离子可诱导培养的大鼠垂体细胞（GH3细胞）释放催乳素。已证明TRH以及高钾（50 mM）可增加这些细胞的45Ca2+外流。使用亲脂性阳离子三苯甲基鏻离子（TPMP+）间接测定TRH和高钾对膜极化的影响。GH3细胞的静息膜电位为-50±1.7 mV。TRH可显著增加45Ca2+外流并刺激催乳素释放，但对同时测量的膜极化没有影响。高钾也增加了45Ca2+外流和催乳素释放，使GH3细胞去极化，这可通过[3H]TPMP+外流的显著增加得到证明。这些结果表明，TRH和高钾可能通过不同机制增加细胞内Ca2+并刺激催乳素释放。
