||Extrapulmonary Effects of NO2 as Reflected by Pentobarbital-Induced Sleeping Time in Mice.
Miller, Frederick J. ;
Graham, Judith A. ;
Illing, Joseph W. ;
Gardner, Donald E. ;
||Health Effects Research Lab., Research Triangle Park, NC.
Nitrogen dioxide ;
Laboratory animals ;
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The influence of nitrogen dioxide (NO2) on pentobarbital(PEN)-induced sleeping time (S.T.) was investigated in mice. Acute exposure to concentrations as low as 470 micrograms NO2/cu m (0.25 ppm) caused a significant increase in PEN-induced S.T. No significant effects on PEN-induced S.T. were detected after 1 or 2 days (3 h/day) exposure to 235 micrograms NO2/cu m (0.125 ppm). None of the exposure regimens affected the time required for the drug to induce sleep. When the effects of repeated daily exposures (3 h/day) to 9400 micrograms NO2/cu m 5 ppm) were compared in male and female mice, the females had a significantly increased PEN-induced S.T. after 1 and 2 days of exposure. However, an increase in PEN-induced S.T. was not observed in males until the 3rd day of exposure. Since the duration of PEN-induced S.T. is primarily determined by hepatic mixed function oxidase activity, it is possible that NO2 may alter some aspects of xenbiotic metabolism.