The role of hyperoxygenation in facilitating the induction of pulmonary histiocytosis by low doses of chlorphentermine

Systematically applied chemicals that damage lung tissue

A large, and increasing number of drugs and chemicals have been found which are toxic to lung following systemic administration. These agents damage lung tissue specifically, or in addition to damage to other tissues. Mechanisms explaining the pulmonary damage produced by some lung toxins have been uncovered. These include concentration of the agent within lung, the absence of adequate pulmonary detoxication systems, and bioactivation to a toxic species within specific lung cells or at distant sites followed by transport to the lung. The basic biochemical lesions underlying lung damage, responses of individual lung cells and pulmonary repair processes to the toxic agent, and species and age differences in susceptibility to lung damage have not, however, been well defined for most lung toxins. This review describes the information available on pulmonary biochemical and pathological changes associated with some of these lung-toxic agents. In addition, mechanisms proposed to explain the lung damage are discussed. The agents covered include: paraquat, the thioureas, butylated hydroxytoluene, the trialkylphosphorothioates, various lung-toxic furans and antineoplastic agents, the pyrrolizidine alkaloids, metals and organometallic compounds, amphiphilic agents, hydrocarbons, oleic acid, 3-methylindole, and diabetogenic agents. Detailed reviews on the overall toxicity of many of these agents have been published elsewhere. This review concentrates on their pulmonary toxicity. Information is presented as an overview to illustrate both the extensive literature that is available and the important questions that remain to be answered about systemic chemicals that damage lung tissue.

Chlorphentermine-induced alterations in pulmonary phospholipid content in rats

Daily, intraperitoneal administration of the anorectic drug chlorphentermine (30 mg/kg) for 5 days to rats significantly increased phosphatidylcholine and total phospholipid content after 1 week and reached a maximal level 4 weeks after treatment in whole lung tissue (unlavaged lungs) and in sessile tissue in which alveolar lipids and macrophages were removed by pulmonary lavage (lavaged lungs). In lavaged lung, a significant rise in the content of sphingomyelin, phosphatidylserine plus phosphatidylinositol component, and phosphatidylethanolamine plus phosphatidylglycerol fraction occurred after 2 weeks, remained at this increased level for 4 weeks, and was followed by a return to control amounts after 5 weeks. In unlavaged lung, the chlorphentermine-induced elevation in sphingomyelin content seen after 1 week persisted at this same significant level even 5 weeks after treatment. Regardless of experimental duration, pulmonary glycogen levels were not altered markedly by chlorphentermine in unlavaged or lavaged tissue. Phenobarbital (30 mg/kg) did not markedly alter pulmonary glycogen and phospholipid component levels. Simultaneous phenobarbital and anorectic drug administration prevented the chlorphentermine-induced rise in total phospholipid, sphingomyelin, and phosphatidylcholine in unlavaged lung without a change in glycogen. A 7-day withdrawal from chlorphentermine treatment in rats previously injected with drug for 2 weeks resulted in a return to control in the levels of sphingomyelin, phosphatidylcholine, and total phospholipid in unlavaged lung. Extension of withdrawal from treatment for 2 weeks produced a significant decrease in all phospholipid components below control values, suggesting that a possible imbalance in synthetic and catabolic activity may persist after drug removal. The concentration of lung glycogen was not altered significantly by chlorphentermine treatment or withdrawal from drug administration. Our results indicate that the chlorphentermine-induced rise in phospholipid components was time-dependent in lavaged and unlavaged lungs, and the increase in phosphatidylcholine occurred independently of a change in glycogen. In addition, the present study shows that the chlorphentermine-induced changes in phospholipid levels are reversible and almost completely prevented by phenobarbital.

Modification by phenobarbital of chlorphentermine-induced changes in lung morphology and drug-metabolizing enzymes in newborn rats

Treatment of newborn rat pups with 60 mg/kg.d chlorphentermine for 7 d produced on accumulation of alveolar foam cells accompanied by an increase in relative pulmonary tissue weight. In contrast, administration of 20 mg/kg.d for 1 wk did not markedly alter lung ultrastructure or weight in newborns. Both doses of chlorphentermine elevated the activity of pulmonary aminopyrine N-demethylase but not that of aniline hydroxylase. The increase in relative liver weight was associated with stimulation of the activities of aniline hydroxylase and aminopyrine N-demethylase in newborns administered either chlorphentermine dose. Phenobarbital treatment produced an increase in relative liver weight accompanied by elevated activities of pulmonary aminopyrine N-demethylase and hepatic aniline hydroxylase and aminopyrine N-demethylase. Simultaneous barbiturate and chlorphentermine administration produced stimulation in liver enzymes to the same extent as phenobarbital alone. In contrast, phenobarbital potentiated the chlorphentermine-induced rise in pulmonary aminopyrine N-demethylase. In the case of 60 mg/kg chlorphentermine and barbiturate, the observed potentiation of lung enzyme activity was associated with a reduction in the number of alveolar foam cells. The results suggest that chlorphentermine and phenobarbital stimulate drug-metabolizing enzyme in lung and liver of newborn rats and that phenobarbital may provide protection against phospholipidosis through stimulation of pulmonary, drug-metabolizing enzymes.

Modification by hyperoxia of chlorphentermine- or phentermine- induced effects on newborn rat lung morphology and metabolism

Treatment of newborns with 20 mg/kg/day chlorphentermine orally for 1 week increased incorporation of thymidine into lung DNA without an associated change in tissue morphology or cyclic AMP levels. An increase in chlorphentermine dose to 60 mg/kg resulted in an accumulation of alveolar hypertrophic macrophages and a rise in incorporation of thymidine into lung DNA; however, cyclic AMP levels were decreased. In contrast, 20 or 60 mg/kg/day for 1 week phentermine-induced depression in the incorporation of thymidine into pulmonary DNA was accompanied by a decrease in cyclic AMP but no apparent alteration in tissue morphology. Hyperoxia did not modify the phentermine-induced changes in cyclic AMP levels and pulmonary ultrastructure. In contrast, hyperoxia altered the responsiveness of newborns to 20 mg/kg chlorphentermine as evidenced by the presence of foam cells. Data suggest that the chlorphentermine-induced increase in DNA synthesis in newborn lung seems independent of changes in cyclic AMP and tha modification of drug-induced alterations by hyperoxia may be related to the chemical structure of a compound.