Zeng S, Guo Z G, Chen H
Laboratory of Molecular Pharmacology, Hu-nan Medical University, Changsha, China.
Zhongguo Yao Li Xue Bao. 1998 Mar;19(2):151-4.
To study the relationship between intracellular calcium translocation and activation of Na+/H+ exchange in thrombin-stimulated platelets.
Intracellular Ca2+ ([Ca2+]i) and pH (pHi) were measured by a dual wavelength fluorophotometer with Fura-2 and pH-sensitive probe BCECF.
Thrombin 0.1 IU.L-1 elicited an increase in platelet [Ca2+]i and pHi, the maximal increase in [Ca2+]i occurred earlier than the rise in pHi. In Na(+)-free buffers, the Na+/H+ exchange was markedly suppressed without affecting the elevation of [Ca2+]i; while intracellular acidification with nigericin 1 mg.L-1 inhibited the increment of [Ca2+]i. Blockade of Ca(2+)-influx with egtazic acid (EGTA) did not affect cytosolic alkalinization. Depletion of intracellular Ca2+ store with ionomycin in the presence of EGTA, no increment in pHi was observed, the basal value of pHi was even more acidic, this response of pHi to thrombin was rehabilitated after refilling of intracellular Ca2+ store with extracellular Ca2+ 1 mmol.L-1.
Intracellular Ca2+ mobilization modulated activation of Na+/H+ exchange, which required an effective increment of [Ca2+]i.
研究凝血酶刺激的血小板中细胞内钙转运与钠/氢交换激活之间的关系。
采用双波长荧光光度计，利用Fura-2和pH敏感探针BCECF测量细胞内Ca2+（[Ca2+]i）和pH（pHi）。
0.1 IU.L-1的凝血酶引起血小板[Ca2+]i和pHi升高，[Ca2+]i的最大升高早于pHi的升高。在无钠缓冲液中，钠/氢交换明显受到抑制，而不影响[Ca2+]i的升高；而1 mg.L-1的尼日利亚菌素引起的细胞内酸化则抑制了[Ca2+]i的增加。用依他酸（EGTA）阻断钙内流不影响胞质碱化。在EGTA存在下，用离子霉素耗尽细胞内钙储存，未观察到pHi升高，pHi的基础值甚至更酸，在用1 mmol.L-1细胞外钙重新填充细胞内钙储存后，pHi对凝血酶的这种反应得以恢复。
细胞内钙动员调节钠/氢交换的激活，这需要[Ca2+]i有效增加。
