Cadmium‐enriched cigarette smoke‐induced cytological and biochemical alterations in rat lungs

Abstract

Male Sprague-Dawley rats were exposed daily for 52 wk in a nose-only exposure system to smoke from the University of Kentucky 2R1 reference cigarettes (SM) or from cigarettes made of cadmium-enriched tobacco (Cd-SM). At sacrifice, the animals were evaluated by bronchoalveolar lavage (BAL) for inflammatory cell response in the lungs, and the cells so obtained were analyzed for phagocytosis of particles (latex and IgG-coated SRBCs) and for their ability to release oxidants upon phagocytic challenge. Additionally, lung tissues were analyzed for Cd levels and lung homogenate fractions were assayed for aryl hydrocarbon hydroxylase (AHH) as well as total and selenium-dependent glutathione peroxidase (GSH-Px) activities. BAL cell counts showed a significant influx of inflammatory cells into the lungs of the Cd-SM group but not the SM group. The proportion of neutrophils in the BAL cells of the Cd-SM group was elevated to 40 +/- 9%, compared with less than 2% in the SM group. Phagocytosis of both types of particles by macrophages from SM and Cd-SM groups was similar to that of the control groups, except that a greater uptake of latex particles was seen in Cd-SM macrophages. The release of oxidants (superoxides and hydrogen peroxide) by the BAL cells was severely impaired in the Cd-SM group, whereas a slight stimulation was seen in the SM group. Pulmonary GSH-Px activity was the same in all groups. A significant induction of the pulmonary AHH activity was observed in the SM group only. The Cd levels in the lungs were approximately 8- and 200-fold greater than controls in SM and Cd-SM groups, respectively. These observations suggest a significant influence of tobacco Cd on the toxicity of cigarette smoke.