Gas chromatographic determination of methylcyclopentadienylmanganesetricarbonyl in biological tissues and fluids

Comparison of the toxicity of methylcyclopentadienyl manganese tricarbonyl with that of its two major metabolites

Pneumotoxicity and lethality resulting from administration of methylcyclopentadienyl manganese tricarbonyl (MMT) and its 2 major metabolites in rats were compared. Following i.p. injection, MMT was found to have an LD50 value of 12.1 mg/kg. Neither of the metabolites appeared to have significant acute toxicity even when doses as high as 250 mg/kg were given. This impressive difference in toxicity may be due in part to changes in solubility of the metabolites, allowing for (1) decreased distribution into the central nervous system, coupled with (2) a more rapid excretion rate. This suggests that the oxidative metabolism of MMT that results in the formation of these metabolites is an important detoxifying pathway.

Potentiating effects of oxygen in lungs damaged by methylcyclopentadienyl manganese tricarbonyl, cadmium chloride, oleic acid, and antitumor drugs

The intraperitoneal administration of methylcyclopentadienyl manganese tricarbonyl (MMT) and cyclophosphamide, exposure to an aerosol of cadmium chloride, intravenous administration of oleic acid, and intratracheal instillation of bleomycin to young female BALB/c mice or CD/CR rats result in acute lung injury. Pulmonary morphology and lung collagen content were examined in animals treated with these chemicals alone or in combination with an elevated oxygen concentration (80%) in the inspired air. In mice, the development of fibrosis could be significantly enhanced if animals treated with MMT, cadmium chloride, cyclophosphamide, or bleomycin were exposed to 80% oxygen immediately following exposure to these agents. In rats only cyclophosphamide- and bleomycin-induced acute lung injury was potentiated by hyperoxia, resulting in significant enhancement of lung collagen content. The pathogenesis responsible for this differential species response of pulmonary injury to hyperoxia remains to be investigated.

Modification of lung tumor development in A/J mice

Strain A mice were injected with urethan, 3-methylcholanthrene or dimethylnitrosamine and given repeated injections of butylated hydroxytoluene (BHT). This treatment significantly increased multiplicity of lung tumors induced by all 3 carcinogens. Two other antioxidants, butylated hydroxyanisole (BHA) or alpha-tocopherol (vitamin E) did not enhance tumor formation, nor did methylcyclopentadienyl manganese tricarbonyl (MMT), an agent capable of producing cell proliferation in lung. Lungs were more susceptible to the carcinogenic action of urethan 2 weeks following BHT-induced injury, but not during the phase of acute cell proliferation in lung. It is concluded that the effects of BHT on lung tumor development in mice are not related to its properties as an antioxidant or to its capability to produce extensive cell proliferation in lung.