Petroleum hydrocarbon toxicity in vitro: effect of n-alkanes, benzene and toluene on pulmonary alveolar macrophages and lysosomal enzymes of the lung

Abstract

The in vitro effects of straight chain alkanes (nC6-nC10), benzene and toluene on pulmonary alveolar macrophages (PAM) of rats and rabbits was studied. The concentrations used ranged from 0.02 to 1.0 mM. All hydrocarbons used in the study were cytotoxic to isolated cultured PAM cells in a dose-dependent manner. The LC50 for these hydrocarbons towards rat PAM cells was estimated to be 1.0 mM for nC8, 2 mM for nC7, 5 mM for nC9 and 10 mM for nC6, nC10, benzene and toluene. Rabbit PAM cells were more sensitive to the hydrocarbons, resulting in and LC50 half that for rat PAM cells. Hydrocarbons also caused extracellular release of the lysosomal enzymes cathepsin D (EC 3.4.23.5) and cathepsin B (EC 3.4.22.1) in a manner corresponding with cell damage. There was more cathepsin D activity released from cells than cathepsin B. In addition, hydrocarbons also caused the release of cathepsin B and D from isolated lysosomes, and there was 10-15% more enzyme activity released in the culture medium of lysosomes exposed to concentrations of 0.5 and 1.0 mM compared to PAM cell cultures of either rats or rabbits. Hydrocarbons also caused loss of cell respiration and stimulated a dose-dependent and a time-dependent increase in lipid peroxidation. The two alkanes nC7 and nC8 caused the greatest increase in lipid peroxidation and the greatest loss of cell respiration. The results indicate that there is a relationship between chain length of alkanes and their cytotoxicity to PAM cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Toluene-induced oxidative stress in several brain regions and other organs

“…Previous studies have indicated that exposure of rat and rabbit pulmonary alveolar macrophages to toluene, in vitro, induced lipid peroxidation (Suleiman, 1987). These results parallel our findings of toluene-induced increases in TBARS in the liver.…”

“…However, in humans and in animals, small quantities of toluene may be converted by phenolic compounds by the enzyme arylmonooxygenase and by epoxide formation of the aromatic nucleus, leading to potentially harmful reactive intermediates (Gerarde and Ahlstrom, 1966;Bakke and Scheline, 1970;Laham, 1970;Jerina and Daly, 1974). In vitro studies of benzene and toluene in pulmonary alveolar macrophages have shown a loss of cell respiration and a dose-dependent and time-dependent increase in lipid peroxidation (Suleiman, 1987).…”

Effects of toluene and its metabolites on cerebral reactive oxygen species generation

“…Toluene has been shown to induce lipoperoxidation in pulmonary alveolar macrophages [20], while p-xylene, a structural analogue, caused similar increases in lung microsomes [21]. Given these findings, this study was undertaken to determine whether reactive oxygen species and related membrane events play a role in the neurotoxicity that results from toluene exposure.…”

Lung Cytotoxicity of Combined Exposure to Refractory Ceramic Fibres and Cigarette Smoke

“…Most of the articles dealing with the activities of lysosomal enzymes in AM after in vivo or in vitro exposure to respirable substances describe the intra -and extracellular concentration or activity of these enzymes after incubation of the isolated AM in the medium. Increased (often dose dependent) leakage into the medium (and consequently decreased activities in the intracellular space) are mentioned 20,[26][27][28] . We did not incubate the isolated BAL cells because we did not want to monitor the leakage of lysosomal enzymes.…”