Effect of lyophilization and storage of liver 9,000xg supernatant fraction on the metabolism of imipramine in several species of animals.

Effects of lyophilization and storage of liver 9,000xg supernatant fraction on the activity of drug metabolizing enzymes in some species of animals were studied. Imipramine metabolizing enzyme activity and the content of cytochrome P-450 were stable for, at least, one month without any loss of the activity when lyophilized liver 9,000xg supernatant fraction of some animal species, i.e., rat, mouse, guinea pig, rabbit and dog, was stored under reduced pressure in a deep freezer (-20 degrees C). There were no differences of imipramine metabolism between lyophilized liver 9,000xg supernatant fraction which was kept in a deep freezer for one month and a fresh fraction which was prepared immediately before determinations of the enzyme activity and cytochrome P-450. The data presented here indicated that the lyophilized preparation of the liver 9,000xg supernatant as well as the fresh preparation can be used for the determination of the drug metabolizing enzyme activity.