The inactivation of hexobarbital induced preferably by cyclohexane inhalation

Female mice inhaled 2X10(-4) mol/l cyclohexane for 0.5--3 days. No change was seen after 0.5 days in the hexobarbital (HB) sleeping time and in its half-life in blood plasma. However, after 1 day there was a decrease by 50 and 60%, respectively. The steep increase in HB-inactivation between 0.5 and 1 day was seen at least 12 h before the main increase in ethylumbeliferone dealkylase and NADPH-P-450 reductase activity and in the cytochromes P-450 and b5 per liver. It could be prevented by actinomycin D and diminished to 25% by cycloheximide. Remarkably after 3 days of CH-inhalation, no more than 65--68% decrease of sleeping time and plasma half-life had been reached. It is concluded that the inactivation of HB is preferably induced compared to the dealkylase. However, it seems to come to a steady state during the main increase of dealkylase, reductase and cytochromes.