[Transport of electrons from mitochondria to microsomes in the reconstituted system of cell organelles]

The reduction of cytochrome P-450--CO complex in the presence of various agents in the reconstituted system of liver cell organelles was studied. The reconstituted system was obtained by the preincubation of isolated liver microsomes and mitochondria of the rats kept on a prolonged phenobarbital diet. The addition of glutamate (but not succinate), NAD+ and amytal (or rotenone) to the reconstituted system caused a 40-50% reduction of NADPH-reducible cytochrome P-450. The inhibitor of mitochondrial NADH-cytochrome b5 reductase dicumarol prevented the cytochrome P-450 reduction in the presence of glutamate, NAD+ and amytal but did not affect the reduction of cytochrome P-450 by the added NADH. It was concluded that the electron transfer from the NAD-dependent substrates of the inner mitochondrial respiratory chain to the microsomal cytochrome P-450 occurs with the participation of non-bound NAD and cytochrome b5 of the outer mitochondrial membrane on the condition that the membranes of the two main oxidative systems are in tight contact.