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肝细胞中独立于刺激的肌醇1,4,5-三磷酸形成的振荡性胞质钙波

Oscillatory cytosolic calcium waves independent of stimulated inositol 1,4,5-trisphosphate formation in hepatocytes.

作者信息

Rooney T A, Renard D C, Sass E J, Thomas A P

机构信息

Department of Pathology and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107.

出版信息

J Biol Chem. 1991 Jul 5;266(19):12272-82.

PMID:2061312
Abstract

The mechanisms underlying agonist-induced oscillations in intracellular free calcium ion concentration ([Ca2+]i) in hepatocytes were investigated by utilizing tert-butyl hydroperoxide (TBHP) as a tool to perturb hepatocyte Ca2+ homeostasis independent of receptor activation. In permeabilized hepatocytes, TBHP inhibited Ca2+ uptake into the inositol 1,4,5-trisphosphate (InsP3)-sensitive Ca2+ pool and increased the sensitivity to InsP3 for Ca2+ release. The effects of TBHP could be mimicked by addition of oxidized glutathione (GSSG) and reversed by pretreatment with dithiothreitol. TBHP and GSSG had no effect on the metabolic degradation of [3H]InsP3 in permeabilized cells. The effect of TBHP on [Ca2+]i in intact cells was investigated by digital imaging fluorescence microscopy of Fura-2-loaded primary cultured hepatocytes. TBHP treatment initiated a series of [Ca2+]i oscillations similar to those caused by Ca2(+)-mobilizing hormones. Moreover, in common with the actions of hormones in these cells (Rooney, T.A., Sass, E., and Thomas, A,P. (1990) J. Biol. Chem. 265, 10792-10796), the [Ca2+]i oscillations induced by TBHP propagated through the cell as Ca2+ waves, originating from a discrete subcellular locus identical to that for phenylephrine-induced [Ca2+]i oscillations. The Ca2+ waves induced by TBHP had similar rates of progress (24-27 microns.s-1) to those generated by phenylephrine. Removal of extracellular Ca2+ increased the initial latency of the TBHP responses, but had no effect on the amplitude or rate of propagation of the Ca2+ waves. Addition of TBHP to cells in the presence of phenylephrine converted the oscillatory phenylephrine [Ca2+]i response into a sustained [Ca2+]i increase. The effects of TBHP in intact cells occurred in the absence of any stimulated inositol polyphosphate formation as measured in populations of [3H]inositol-labeled hepatocytes. The data indicate that spatially organized [Ca2+]i oscillations in intact hepatocytes can occur without any requirement for phospholipase C activation. Furthermore, for agents that act by mobilizing Ca2+ from the InsP3-sensitive pool, the kinetics of the Ca2+ release phase of the [Ca2+]i oscillations appears to be independent of the nature of the stimulus.

摘要

利用叔丁基过氧化氢(TBHP)作为一种独立于受体激活来扰乱肝细胞钙离子稳态的工具,研究了肝细胞内游离钙离子浓度([Ca2+]i)激动剂诱导振荡的潜在机制。在通透的肝细胞中,TBHP抑制钙离子摄取到肌醇1,4,5-三磷酸(InsP3)敏感的钙离子池中,并增加了对InsP3释放钙离子的敏感性。添加氧化型谷胱甘肽(GSSG)可模拟TBHP的作用,用二硫苏糖醇预处理可逆转其作用。TBHP和GSSG对通透细胞中[3H]InsP3的代谢降解没有影响。通过对负载Fura-2的原代培养肝细胞进行数字成像荧光显微镜观察,研究了TBHP对完整细胞中[Ca2+]i的影响。TBHP处理引发了一系列类似于钙离子动员激素引起的[Ca2+]i振荡。此外,与这些细胞中激素的作用相同(鲁尼,T.A.,萨斯,E.,和托马斯,A.P.(1990年)《生物化学杂志》265,10792-10796),TBHP诱导的[Ca2+]i振荡以钙离子波的形式在细胞中传播,起源于与去氧肾上腺素诱导的[Ca2+]i振荡相同的离散亚细胞位点。TBHP诱导的钙离子波的进展速度(24-27微米·秒-1)与去氧肾上腺素产生的速度相似。去除细胞外钙离子增加了TBHP反应的初始潜伏期,但对钙离子波的幅度或传播速度没有影响。在去氧肾上腺素存在的情况下,向细胞中添加TBHP将振荡性的去氧肾上腺素[Ca2+]i反应转变为持续性的[Ca2+]i增加。在[3H]肌醇标记的肝细胞群体中测量发现,TBHP在完整细胞中的作用发生在没有任何刺激的肌醇多磷酸形成的情况下。数据表明,完整肝细胞中空间组织化的[Ca2+]i振荡可以在不需要磷脂酶C激活的情况下发生。此外,对于通过从InsP3敏感池中动员钙离子起作用的试剂,[Ca2+]i振荡的钙离子释放阶段的动力学似乎与刺激的性质无关。

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