Cytotoxicity of phenol red in toxicity assays for carbon nanoparticles.

To explore the novel properties of carbon nanoparticles (CNPs) in nanotoxicity assays, the adsorption of phenol red (a pH indicator for culture medium) by multi-walled carbon nanotubes (MWNTs) and three kinds of carbon blacks (CBs) with nanosize, and its effects on cytotoxicity were studied. Results indicated that the phenol red adsorbed and delivered into cells by CBs was responsible for the toxicity to Hela cells in the medium without serum. The cellular uptake of phenol red was verified using 125I-labeling techniques. The size-dependent cytotoxicity of CBs was found to closely correlate to adsorption of phenol red, cellular uptake of phenol red-CB complexes and the amount of phenol red delivered into the cells by CBs. Although the CBs were either nontoxic or slightly toxic, as vehicles of phenol red, they played an essential role in the cytotoxicity induced by phenol red. However, MWNTs showed an intrinsic cytotoxicity independent of phenol red. The implications associated with these findings are discussed.

The effects of 17alpha-ethynylestradiol, 4-nonylphenol and phenol red on vitellogenin synthesis in juvenile Chalcalburnus tarichi primary hepatocyte culture.

In this study, the effects of the endocrine-disrupting chemicals known as 17α-ethynylestradiol (EE2), 4-nonylphenol (NP) and phenol red on vitellogenin (Vtg) synthesis in juvenile Chalcalburnus tarichi primary hepatocyte culture were investigated depending on dose and time. Hepatocytes were isolated by collagenase perfusion method and the cells were kept alive in cell culture for more than 2 weeks without using serum. As a result, it was determined that EE2 increased the Vtg synthesis depending on dose and time (p < 0.05), while NP and phenol red did not have any effect on the Vtg synthesis in the Chalcalburnus tarichi primary hepatocyte culture. Besides that, it was observed that high doses of NP (10( -3) and 10(-4)M) had toxic effects to the hepatocyte culture, too.

Does paracellular permeability play a role in cholephilic dye-induced cholestasis?

Changes in hepatic paracellular permeability were investigated during the development of cholephilic dye-induced cholestasis in rats. For this purpose, four dyes with different cholestatic potency (phenol red, sulfobromophthalein, bromcresol green and rose bengal) were infused at a high, potentially damaging dose (280 nmol/min per 100 g body wt., i.v.), and changes in paracellular permeability were continuously monitored by measuring the access into bile of the permeability probe -14C-sucrose. The cholestatic potency of the different dyes was: rose bengal > bromcresol green > sulfobromophthalein > phenol red. All dyes increased [14C]sucrose bile-to-plasma ratio, producing a displacement towards curves of higher permeability. The capability of the dyes to increase biliary permeability followed the same order as their respective cholestatic potencies. The possible implications of the present results for cholephilic dye-induced cholestasis are discussed.