Determination of human liver cytochrome P-450 by electron paramagnetic resonance of liver biopsies.

Human liver cytochrome P-450 level has beenen determined by direct electron paramagnetic resonance spectroscopy at 77 degrees K of liver specimens obtained by surgical biopsy. A preliminary experiment with rat livers was performed in order to calibrate the intensity of the cytochrome P-450 EPR signal as a function of the cytochrome concentration obtained by the classical spectrophotometric method. 44 subjects have be examined. We found a cytochrome P-450 value of 21.5 plus or minus 11.2 nmoles per gram of liver in normal subjects. Variations of this level in some pathological liver states are discussed.