NADPH-dependent reduction of cytochrome P-450 in liver microsomes from vitamin C-deficient guinea pigs: effect of benzphetamine.

The effect of dietary vitamin C on the reduction of cytochrome c and cytochrome P-450 by NADPH-cytochrome P-450 reductase was determined in guinea pig liver microsomes. Acute vitamin C deficiency decreased hepatic microsomal cytochrome P-450 content 21% and the rate of cytochrome P-450 reduction 66% without affecting cytochrome c reduction. However, the vitamin status of the animals did not affect the enhancement in cytochrome P-450 reduction produced by the addition of a type I substrate to the reaction mixture. The results suggest that vitamin C deficiency selectivity affects the transfer of electron from NADPH to cytochrome P-450 and that this effect does not result from a change in the spin state of cytochrome P-450.