Role of calcium and cAMP messenger systems in intracellular pH regulation of osteoblastic cells.
Role of calcium and cAMP messenger systems in intracellular pH regulation of osteoblastic cells.
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钙和 cAMP 信使系统在成骨细胞细胞内 pH 调节中的作用。
DOI：
10.1152/ajpcell.1992.262.1.c111
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Kleeman,CR
中科院分区：
文献类型：
--
作者：
Green,J;Kleeman,CR
我们最近发现，在成骨细胞表型细胞系UMR-106(Na(+)-H+反向转运体和Na(+)-非依赖的Cl(-)-HCO3(-)-OH-交换器)中，phi的调节涉及两种机制。在本工作中，我们使用对pH敏感的染料2‘，7’-bis(2-carboxyethyl)-5，6-carboxyfluorescein以及同位素通量来研究第二信使对这些转运蛋白活性的影响。UMR-106细胞内钙离子浓度升高(用Fura-2荧光法测量)后伴随着氯(-)-HCO3-交换器的刺激，导致胞浆酸化。随后，在Na(+)-H+交换器的介导下，细胞碱化将phi恢复到其静止值。[Ca~(2+)]的急剧下降会突然停止阴离子交换器的活性，而对Na(+)-H~+交换器的活性没有影响。Ca~(2+)对阴离子交换器的刺激作用呈剂量依赖性，并可被钙调蛋白抑制剂N-(6-aminohexyl)-5-chloro-naphthalenesulfonamide和卡咪唑所阻断。Forsklin、8-bromo-cAMP或前列腺素E_2引起细胞内3‘，5’-环磷酸腺苷(CAMP)升高，导致Na(+)-H+逆向转运体和阴离子交换器的活性受到抑制。CAMP对Cl(-)-HCO3-交换的抑制作用可通过升高[Ca~(2+)]_i来克服。我们得出结论：1)钙离子和cAMP可通过改变phi调节机制的活性来影响成骨细胞的phi；2)钙离子的作用可能是通过钙调素来实现的。
We have recently shown that two mechanisms are involved in the regulation of pHi in the osteoblastic phenotype cell line UMR-106 (Na(+)-H+ antiporter and a Na(+)-independent Cl(-)-HCO 3(-)-OH- exchanger). In the present work, we used the pH-sensitive dye 2',7'-bis(2-carboxyethyl)-5,6-carboxyfluorescein as well as isotope fluxes to investigate the influence of second messengers on the activity of these transporters. Elevation in intracellular calcium concentration [( Ca2+]in) in UMR-106 cells (measured by fura-2 fluorescence) is followed by stimulation of the Cl(-)-HCO3- exchanger, leading to cytosolic acidification. Subsequently, cell alkalinization, mediated by the Na(+)-H+ exchanger, restores pHi to its resting value. An acute reduction in [Ca2+]in abruptly stops the activity of the anion exchanger while having no influence on the activity of the Na(+)-H+ exchanger. The stimulatory effect of Ca2+in on the anion exchanger is dose dependent and is abrogated by the calmodulin inhibitors N-(6-aminohexyl)-5-chloro-naphthalenesulfonamide and calmidazolium. An increase in intracellular adenosine 3',5'-cyclic monophosphate (cAMP) brought about by forskolin, 8-bromo-cAMP, or prostaglandin E2 leads to inhibition of activity of both the Na(+)-H+ antiporter and the anion exchanger. The suppressive effect of cAMP on Cl(-)-HCO3- exchange could be overcome by elevating [Ca2+]in. We conclude that 1) Ca2+in and cAMP can influence pHi in osteoblasts by altering the activities of pHi regulatory mechanisms and 2) the effect of Ca2+in is probably mediated by calmodulin.