EFFECTS OF COLD PRESERVATION AND REPERFUSION ON MICROSOMAL CYTOCHROMEP-450-LINKED MONOOXYGENASE SYSTEM OF THE RAT-LIVER

The effects of cold preservation and reperfusion of the liver on the h epatic microsomal cytochrome P-450-linked monooxygenase system (P-450 system) were investigated. Rat livers were preserved with cold Univers ity of Wisconsin solution for 0, 12, 24, 36, and 48 hr. Half of them i n 0-, 24-, and 48-hr groups were reperfused for 1 hr at 37 degrees C w ith oxygenated Krebs-Henseleit buffer. After preservation or reperfusi on, the liver microsomes were prepared and the concentration of each c omponent of the P-450 system [NADPH-cytochrome bg reductase (bg reduct ase), cytochrome b(5) (b(5)), NADPH-cytochrome P-450 reductase (P-450 reductase) and cytochrome P-450 (P-450)] and their drug metabolizing a ctivities and concentration of apo cytochrome P-450 2E1 (apo-P-450 2E1 ) were measured. After 48-hr preservation, b(5) concentration did not decrease, whereas the concentration of P-450, P-450 reductase, and b(5 ) reductase decreased from 0.865 to 0.676 nmole/mg protein, from 0.262 to 0.233 mu mole/mg protein/min and from 5.34 to 4.86 mu mole/mg prot ein/min, respectively. During cold preservation, the activities of p-n itroanisole O-demethylase and aniline p-hydroxylase did not change. Am inopyrine N-demethylase activity was inhibited from 4.45 to 3.34 nmole /mg protein/min after 48-hr cold preservation. Apo-P-450 2E1 was gradu ally decreased during cold preservation. Reperfusion caused a further decrease in the activities and concentration of the components of the P-450 system and concentration of apo-P-450 2E1 to 80-90% after 1-hr r eperfusion. It was suggested that the prolonged preservation caused de terioration of the P-450 system and the loss of the abilities of metab olism and detoxication of xenobiotics. (C) 1996 Academic Press, Inc.