RESUMO
Occupational exposure to oyster mushroom (Pleurotus ostreatus) has been associated with obstructive lung disease. Previously, we studied an extract of oyster mushroom (OME) and determined that it causes dose-dependent contractions of nonsensitized guinea pig trachea (GPT). We extend these studies to the investigation of sensitized tissue. In the present study 24 animals were sensitized using ovalbumin (OA) and subsequently challenged with an aerosol of 2.5% OA. A control group of 12 nonsensitized GPs was also studied. Tracheas were removed and were divided into rings in which the epithelium was retained (EP+) or removed (EP-). Dose-related contractions of sensitized and nonsensitized GPTs were elicited with OME. In nonsensitized animals the EP+ GPTs demonstrated a significantly greater response to OME (100-1000 µl) than did the EP- GPTs (p < 0.01). By contrast, in sensitized GPTs with and without epithelium there was no difference to challenge with OME. Finally, sensitized GPTs with and without epithelium and nonsensitized GPTs with epithelium responded similarly to challenge with OME. These findings suggest that in nonsensitized animals there is an enhancement of contractile response to OME which is in part mediated by the GPT epithelium. In sensitized animals with or without epithelium, the level of bronchoconstrictor response is similar to that of the nonsensitized animals with epithelium, suggesting an enhanced constrictor response independent of epithelium in the sensitized animals.