Spectrophotometric analysis of cytochromes in Morris hepatomas.

The contents of mitochondrial and microsomal cytochromes in slowly growing Morris hepatomas have been determined spectrophotometrically and compared with those in the livers of the host, normal adult, and embryo and in regenerating livers. As compared to the normal adult livers, the hepatomas are characterized by ( a ) the low content of cytochromes a + a 3, b , and c 1 and nearly equal levels of cytochrome c in mitochondria, giving a low a + a 3/ c ratio, and ( b ) low contents of cytochromes b 5 and P-450 in microsomes. Analysis in whole homogenates of hepatomas showed more pronounced decrease of the amount of cytochrome a + a 3, presumably due to the decrease of the number of mitochondria in hepatoma cells. The livers of the tumor-bearing rats are also characterized by the similar, although less significant, cytochrome pattern observed in tumors. A low a + a 3/ c ratio was also observed in embryonic livers, whereas regenerating liver showed no significant difference in the content of cytochromes as compared to that of the normal adult liver.