Enzymatic Changes in Alveolar Macrophages of Rats Exposed to Lead and Nickel by Inhalation

Effects of nickel hydroxycarbonate on alveolar macrophage functions

The metabolic effects of different concentrations of nickel hydroxycarbonate (NiHC) on guinea pig alveolar macrophages (GPAMs) were investigated. Exposure to high concentrations of NiHC (6.25 and 12.5 micrograms 10(-6) cells) led to cell vacuolization. Morphological changes were associated with a dramatic reduction in the steady-state level of cellular adenosine triphosphate (ATP), i.e. ATP levels were reduced by 35% (P less than 0.001) and 53% (P less than 0.01), respectively. Low concentrations of NiHC (0.0625 and 0.125 microgram 10(-6) cells) did not induce morphological changes but increased cellular ATP content by 19% (P less than 0.01) and 12% (P less than 0.05), respectively. Effects of NiHC (0.125 and 6.25 micrograms 10(-6) cells) on cell oxidative metabolism were studied. The chemiluminescence was significantly increased (P less than 0.001) by the lower but not the higher concentration. A slight inhibition of total superoxide dismutase (P less than 0.05) and a decrease of catalase activity were demonstrated (P less than 0.05) for the high dose, while the low dose decreased the levels of reduced and total glutathione. In conclusion, the effects of NiHC on alveolar macrophages are characterized by an overproduction of free radicals for low concentrations and the depletion of cellular reserve energy, particularly ATP, for high concentrations.

Toxicity to alveolar macrophages in rats following parenteral injection of nickel chloride

Alveolar macrophages collected by pulmonary lavage from male Fischer-344 rats at intervals (1-72 hr) after NiCl2 injection (62-500 mumol/kg, sc) were tested by several techniques. Within 1 to 4 hr, the macrophages showed morphological and biochemical signs of activation (hypertrophy, ruffled plasma membrane, increased cyclic AMP concentration, and markedly diminished 5'-nucleotidase activity, assayed by concanavalin A inhibition). Functional impairment (reduced phagocytic activity) was first seen at 24 hr; lipid peroxidation (increased malondialdehyde concentration) was not detected until 48 hr. Dose- and time-related effects of NiCl2 on 5'-nucleotidase activity, phagocytic activity, malondialdehyde concentration, and nickel content of alveolar macrophages were observed 24 to 72 hr postinjection. Diminished cell viability occurred only at 72 hr after the highest dosage of NiCl2. In alveolar macrophages from 63NiCl2-treated rats, 63Ni was located primarily in the cytoplasm, based upon liquid scintillation counting and autoradiography; fractionations of macrophage cytosol by gel filtration chromatography showed that 63Ni was bound to several high- and low-molecular-weight constituents. This study demonstrates that sc administration of NiCl2 to rats caused nickel uptake into and activation of alveolar macrophages, followed by reduced phagocytic capacity. The alveolar macrophage was a cellular target for nickel toxicity following parenteral exposure to NiCl2.

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.