RESUMO
Response to cadmium cytotoxicity of cultured bovine aortic smooth-muscle cells was compared with that of cultured bovine aortic endothelial cells and porcine kidney epithelial LLC-PK1 cells. The cell damage was evaluated by morphology and the lactate dehydrogenase leakage assay. It was found that vascular smooth-muscle cells are markedly sensitive to cadmium cytotoxicity. The accumulation of intracellular cadmium was much higher but that of metallothionein was much less in vascular smooth-muscle cells than in LLC-PK1 cells; vascular endothelial cells were in between vascular smooth-muscle cells and LLC-PK1 cells. The content of reduced glutathione was slightly increased by cadmium in all three cell types. The present data suggest that a much lower inducibility of metallothionein with a high accumulation of intracellular cadmium in vascular smooth-muscle cells resulted in a marked sensitivity of the cells to cadmium cytotoxicity. Vascular smooth-muscle cells may be one of the critical target of cadmium toxicity.
Assuntos
Cádmio/toxicidade , Endotélio/efeitos dos fármacos , Rim/efeitos dos fármacos , Músculo Liso Vascular/efeitos dos fármacos , Animais , Bovinos , Contagem de Células , Células Cultivadas , Endotélio/citologia , Endotélio/patologia , Células Epiteliais , Epitélio/efeitos dos fármacos , Epitélio/patologia , Rim/citologia , Rim/patologia , L-Lactato Desidrogenase/efeitos dos fármacos , L-Lactato Desidrogenase/metabolismo , Células LLC-PK1 , Metalotioneína/efeitos dos fármacos , Metalotioneína/metabolismo , Músculo Liso Vascular/patologia , SuínosRESUMO
Metallothionein synthesis induced by bismuth nitrate was characterized using a cell culture system. It was found that bismuth (1-10 microM) significantly increased the intracellular accumulation of metallothionein in bovine aortic endothelial cells without an exhibition of cytotoxicity and a change of either general protein synthesis or proliferative DNA synthesis after a 24-h incubation. A low increase in the metallothionein accumulation was observed in bovine aortic smooth muscle cells; however, porcine kidney epithelial LLC-PK1 cells, human Chang liver cells and two human hepatoma cell lines (HLF cells and Hep-G2 cells) did not respond to bismuth. Other cations including cobalt, lead and zinc at 10 microM failed to induce metallothionein in endothelial cells, although cadmium at 1 microM was a strong inducer. Bismuth accumulated highly in endothelial cells but very slightly in LLC-PK1 cells and Chang liver cells. The present data suggest that bismuth is a selective inducer of metallothionein of vascular endothelial cells and this cell type particularly responds to the cation.