[The cytochrome oxidase activity of the nuclei and nuclear membranes of rat liver cells following partial hepatectomy].

The cytochrome oxidase activity of liver cell nuclei determined in the presence of ascorbate and cytochrome c equals, on the average, 1.2 nmol O2/min/mg protein. This activity tentatively named "free" cytochrome oxidase activity is in nuclei 10% and in nuclear envelopes about 30% of the total cytochrome oxidase activity determined in the presence of tetramethyl paraphenylendiamine. Following the partial hepatectomy, the "free" cytochromoxidase activity in the isolated nuclei is 5-6 times that in the control and approaches the total cytochromoxidase activity which remains at the same level. No increase of free cytochrome oxidase activity in the rat liver homogenate and the isolated mitochondria following the partial hepatectomy was observed.