The present study aimed at investigating whether previously reported interstrain differences of mice in testicular susceptibility to cadmium toxicity can be attributed to different metallothionein expression in the testes and other organs. Furthermore, purified Leydig cell systems were employed to identify a testicular compartment capable to respond specifically to exogenous cadmium by increased metallothionein expression. It was shown that species differences in testicular damage after cadmium administration can not be explained by differences in cadmium-induced stimulation of hepatic and renal metallothionein. In contrast to these organs, no metallothionein response to cadmium was observed in testicular homogenates. However, both freshly isolated and purified rat Leydig cells and a murine tumor Leydig cell line are not only able to synthesize metallothionein under basal conditions, but also respond to exogenous cadmium by increased synthesis of metallothionein (35S-cysteine incorporation) and an increased Mt-mRNA content. Extracts from freshly isolated and purified rat Leydig cells contained a cadmium-binding component which eluted in gel chromatography with the same properties as metallothionein. It was concluded that the use of purified cell systems is a valuable tool to investigate possible targets of cadmium toxicity.

No abstract

Abstract. Isolated rat hepatocytes (1 x 107 cells/ml) were aerobically incubated in Eagle's Minimum Essential Medium which contained 2.0% albumin. As potential parameters of lipid peroxidation ethane and n-pentane formed were measured in samples obtained from the gas phase above the incubation mixture. 15-30 nmol ethane or n-pentane were produced by 107 hepatocytes within 90 min. Carbon tetrachloride (CC14) or ADP-complexed ferrous ions stimulated ethane and n-pentane formation considerably, depending on the concentrations of the compounds. With CC14 107 cells formed max 180 nmol ethane and 140 nmol n-pentane within 90 min incubation, whereas with Fe(II) max 130 nmol ethane and 220 nmol n-pentane could be detected.When n-pentane was added to the gas phase above the incubation mixture containing either medium or medium plus hepatocytes its amount decreased by 30% within the first 5 min of incubation. However, afterwards only minor amounts of n-pentane disappeared, even in the presence of hepatocytes. This indicates that n-pentane equilibrates with the cell suspension under the conditions used.Cell viability, as determined by the release of lactate dehydrogenase into the medium and by the uptake of trypan blue by the cells, and the recovery of the cells decreased only in presence of relatively high concentrations of CC14, or Fe(II) respectively. However, a maximal effect on ethane and n-pentane formation was reached already with lower concentration.

The effects of CdCl2, Na2CrO4, NaAsO2 and NiSO4 on cultured Chinese hamster kidney cells were studied over a concentration range for 48 h. Release of lactate dehydrogenase, a parameter of cell viability, was not closely related to cell proliferation except for Na2CrO4. A better correlation was obtained between glucose consumption and lactate production, and cellular growth. When studying toxic effects of metals in cell-culture systems, metabolic parameters should be determined in addition to cell viability and cellular growth. The results indicate that Chinese hamster kidney cells in culture might be useful to study mechanisms of metal-induced toxicity.

No abstract