ABSTRACT
Colorimeter detection of Evas Blue in formamide extract of rat tracheal tissue is used as an indication of increased vascular permeability induced by introduction of 115 degrees C air into the rat trachea, followed by a dose (20mg/kg) of meperidine given. The increases of tracheal vascular permeability (TVP) and malondialdehyde (MDA) level induced by hot air injury (HAI) are markedly inhibited. The decrease of superoxide dismutase (SOD) activity induced by HAI is raised. The inhibitory effect of meperidine (MIE) on TVP is not antagonized by naloxone. It is implied that the opiate receptor sensitive to naloxone is not involved in the MIE on TVP. The decrease of tracheal MDA content, increase of tracheal SOD activity raising the ability of scavengering oxygen free radicals and reducing the formation of other active oxygen, inhibit lipid peroxidation. These antioxidative effects may be one aspect of the mechanism of the inhibiory effect of meperidine on TVP.