We studied cadmium toxicity in murine hepatocytes in vitro. Cadmium effects on intracellular free Ca2+ concentration ([Ca2+]i) were assayed, using a laser scanning confocal microscope with a fluorescent probe, Fluo-3/AM. The results showed that administration of cadmium chloride (CdCl2, 5, 10, 25 μM) resulted in a dose-dependent decrease of hepatocyte viability and an elevated aspartate aminotransfe rase (AST) activity in the culture medium (p<0.05 for 25 μM CdCl2 vs. control). Significant increases of lactate dehydrogenase (LDH) activities in 10 and 25 μM CdCl2-exposed groups were observed (p<0.05 and p<0.01, respectively). A greatly decreased albumin content and a more malondialdehyde (MDA) formation also occurred after CdCl2 treatment. The Ca2+ concentrations in the culture medium of CdCl2-exposed hepatocytes were significantly decreased, while [Ca2+]i appeared to be significantly elevated (p<0.05 or p<0.01 vs. control). We found that in Ca2+-containing hydroxyethyl piperazine ethanesulfonic acid-buffered salt solution (HBSS) only, CdCl2 elicited [Ca2+]i increases, which comprised an initially slow ascent and a strong elevated phase. However, in Ca2+-containing HBSS with addition of 2-aminoethoxydiphenyl borane (2-APB), CdCl2 caused a mild [Ca 2+] i elevation in the absence of an initial rise phase. Removal of extracellular Ca2+ showed that CdCl2 induced an initially slow [Ca2+]i rise alone without being followed by a markedly elevated phase, but in a Ca2+-free HBSS with addition of 2-APB, CdCl2 failed to elicit the [Ca2+]i elevation. These results suggest that abnormal Ca2+ homeostasis due to cadmium may be an important mechanism of the development of the toxic effect in murine hepatocytes. [Ca2+]i elevation in acutely cadmium-exposed hepatocytes is closely related to the extracellular Ca2+ entry and an excessive release of Ca2+ from intracellular stores., S. S. Wang, L. Chen, S. K. Xia., and Obsahuje bibliografii a bibliografické odkazy
We studied hsBAFF activity in in vitro mouse splenic B cells. hsBAFF effects on intracellular free Ca 2+ concentration ([Ca 2+ ] i ) were assayed, using a laser scanning confocal microscope with fluorescent probe, Fluo-3/AM. We showed that treatment of B cells with 0.5-5 μ g/ml hsBAFF resulted in significantly higher [Ca 2+ ] i levels in a dose-dependent fashion at 12 and 24 h, respectively (p<0.05 or p<0.01 vs. control). Furthermore, we noticed that 2.5 μ g/ml hsBAFF-treated cells were significantly resistant to decrease of cellular viability induced by thapsigargin (Tg), an endoplasmic reticulum (ER) Ca 2+ -ATPase inhibitor (p<0.05 hsBAFF plus Tg group vs. Tg group). Thus hsBAFF may promote B cell survival by direct upregulation of [Ca 2+ ] i physiological homeostasis contri buting to prevention of [Ca 2+ ] i dysfunction. Using immunocytochemistry and Western blot analysis, we found that the activation of ERK1/2 due to hsBAFF was triggered by a [Ca 2+ ] i -dependent pathway, leading to elevation of B cell proliferation. This is supported by the findings that intracellular Ca 2+ chelator BAPTA/AM attenuated phosphorylated ERK1/2 expression and cell proliferation in hsBAFF-stimulated B cells. hsBAFF-stimulated B cell proliferation was obviously reduced by mitogen extracellular kinase 1/2 (MEK1/2, upstream of ERK1/2) inhibitor U0126. Taken together, the main finding of this study is that hsBAFF elicits higher but homeostatic [Ca 2+ ] i levels, which regulates ERK1/2 activity and cell proliferation in in vitro B cells., J. Q. Liang, W. Zhang, L. Wen, W. Gao, S. Q. Zhang, L. Chen., and Obsahuje bibliografii