Pentane clearance from inspired air by the rat: dependence on the liver

Pentane, a volatile hydrocarbon, is cleared from inspired air by the rat. We have studied this clearance to learn whether or not it is a function of the liver. Rats were put individually into airtight chambers which contained CO2 absorbent and were connected to an O2 reservoir. Pentane was injected into each chamber and chamber atmosphere was assayed frequently for pentane over 6 h by gas chromatography. Semilog plots of pentane concentration had a rapid distribution phase and a log-linear terminal elimination phase. A chamber clearance value in milliliters at atmosphere cleared per minute per kilogram rat weight was calculated. Nephrectomy had no effect on pentane clearance. Liver injury by thioacetamide (5 mmol/kg) or by CCl4 (75 or 125 microliters/100 g) was associated with a marked decrease in pentane clearance, indicating a major role for the liver in pentane elimination. Treatment of rats with inducers or inhibitors of the hepatic microsomal cytochrome P450 system did not affect their ability to clear pentane. However, administration of ethanol or 4-methyl-pyrazole diminished pentane clearance, suggesting that alcohol dehydrogenase may be involved in pentane metabolism. These findings demonstrate that pentane clearance is a liver function.