The American journal of pathology
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To investigate the effects of cigarette smoke on the expression of genes encoding intracellular antioxidant species, we exposed rats to whole cigarette smoke or air (control) daily for 1, 2, 7, or 14 days. After sacrifice, RNA was extracted from one lung and expression of mRNA for catalase (CAT), manganese superoxide dismutase (MnSOD), copper-zinc superoxide dismutase (CuZnSOD), glutathione peroxidase (GPX), and metallothionein (MT) was determined by Northern blots and dot blots. The anatomical distribution of expression of these genes was determined by in situ hybridization studies on sections of the contralateral lung. ⋯ This pattern is similar to the phenomenon of clonal heterogeneity described in other tissues but not previously reported in the lung. We conclude that cigarette smoke, like other forms of oxidant attack, transiently increases expression of MnSOD, and up-regulation of MnSOD expression appears to occur particularly in bronchial epithelial cells, which normally express MnSOD at relatively low levels. MT expression is also transiently increased by smoke whereas GPX expression increases after prolonged (7 to 14 days) exposure to cigarette smoke.