Griendling K K, Berk B C, Alexander R W
Department of Medicine, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts 02115.
J Biol Chem. 1988 Aug 5;263(22):10620-4.
Angiotensin II stimulation of vascular smooth muscle cells results in initial, rapid diacylglycerol (DG) formation from the polyphosphoinositides accompanied by intracellular acidification, as well as a more sustained DG accumulation which is accompanied by a prolonged intracellular alkalinization. To determine whether intracellular pH (pHi) modulates DG accumulation, NH4Cl and potassium acetate were used to alter pHi and DG formation was measured. NH4Cl (10 mM) increased pHi from 7.15 +/- 0.05 to 7.34 +/- 0.02 pH units and markedly enhanced the sustained (5 min), but not the initial (15 s), phase of DG formation in response to 100 nM angiotensin II (65 +/- 13% increase). Conversely, intracellular acidification with Na+-free buffer and potassium acetate (20 mM) decreased pHi to 6.93 +/- 0.08 and reduced subsequent angiotensin II-induced sustained DG formation by 82 +/- 9%. In intact cells, inhibition of angiotensin II-stimulated alkalinization by incubation in Na+-free buffer or by addition of the Na+/H+ exchange inhibitor dimethylamiloride (10 microM) decreased the ability of the cell to sustain DG formation, suggesting that active Na+/H+ exchange is necessary for continued DG formation. Thus, it seems that sustained, angiotensin II-induced diacylglycerol accumulation is regulated by intracellular alkalinization secondary to Na+/H+ exchange in cultured vascular smooth muscle cells.
血管紧张素 II 刺激血管平滑肌细胞会导致多磷酸肌醇最初快速形成二酰甘油（DG），同时伴有细胞内酸化，以及更持久的 DG 积累，这伴随着细胞内碱化时间延长。为了确定细胞内 pH（pHi）是否调节 DG 积累，使用氯化铵和醋酸钾来改变 pHi 并测量 DG 形成。氯化铵（10 mM）使 pHi 从 7.15±0.05 增加到 7.34±0.02 个 pH 单位，并显著增强了对 100 nM 血管紧张素 II 反应的 DG 形成的持续（5 分钟）阶段，但不影响初始（15 秒）阶段（增加 65±13%）。相反，用无钠缓冲液和醋酸钾（20 mM）进行细胞内酸化使 pHi 降至 6.93±0.08，并使随后血管紧张素 II 诱导的持续 DG 形成减少 82±9%。在完整细胞中，通过在无钠缓冲液中孵育或添加 Na+/H+交换抑制剂二甲基amiloride（10 μM）抑制血管紧张素 II 刺激的碱化，会降低细胞维持 DG 形成的能力，这表明活跃的 Na+/H+交换对于持续的 DG 形成是必要的。因此，似乎在培养的血管平滑肌细胞中，持续的、血管紧张素 II 诱导的二酰甘油积累受继发于 Na+/H+交换的细胞内碱化调节。
