Intracellular Phosphorus Turnover in the Rat Liver Cell.

Abstract

1. A broad preliminary survey has been made of the metabolic fate of P32 labeled phosphate within the rat liver cell, following intravenous injection of the labeled phosphate. 2. By means of differential centrifugation of rat liver homogenates, 4 intracellular components have been separated out: mitochondria, microsomes, the remaining supernatant, and a crude nuclear fraction. 3. Time-distribution curves have been constructed for the P32 in the 4 cell fractions, and further resolution has been obtained by chemically fractionating the P32 activity in each cell fraction into 4 groups of phosphorus compounds: the acid-soluble compounds, phospholipids, nucleic acids, and protein residue. 4. The mitochondria and nuclei took up P32 rapidly, whereas the microsomes incorporated relatively little P32, and much more slowly. Characteristically different patterns of P32 uptake were also noted for the various chemical fractions. A brief interpretation of the findings is given. 5. Additional data are given for the dry weight, phosphorus and nitrogen content of the cellular fractions from whole rat livers.